How to use a PC power supply to run it all.

[marcoski]

OK I have been asked this many times by PM, so I have decided to post it here.

You will need a 400W or better ATX power supply (£25 new), and a 21W/5W stop / tail car lamp and holder (scrap yard?)

There are a number of multi way plugs on these units, we will deal with each one in turn.

20 way long and thin one:

Pick out the green wire and one of the black wires, cut them off the plug, strip them and join them together. Insulate the join with tape.

Pick another black wire, cut if and connect it to the common wire on your stop/tail lamp.
Pick a red wire and connect it to the stop (21W) section of your stop/tail lamp
Pick a yellow wire and connect it to the tail (5W) section of your stop/tail lamp
Make sure all the joints are insulated properly.

Plug in the power pack and the fans should start. The lamp should come on too, the stop filament (the thicker one) should be relatively dim and the tail one should be bright.

Switch off.

There are several cable harnesses with four way plugs on them. Cut all the yellow wires at the first plug they arrive at (on the power pack in my hand there are four of them) , strip them and join them all together. Cut the same number of black wires and strip and join them too. This pair, yellow (+) and black (-) are your 12 volt supply for charging, etc.

Off the same harness, pick a red and black wire. This is your 5 volt supply for running your lathe!

On the 20 way connector, pick an orange and a black wire. This is your 3.3 volt supply for bedding in motors.

If you are going to dress all the other cables out of the way, make sure that the thin orange wire is still connected to one of the thick orange wires.

You can use all of these outputs at once if desired!

Of course with a spot of woodwork and some fat bolts, you can make a terminal strip for all these wires and connect your crocodile clips to these. Finishing touches are up to you.

[Dave Treacy]

Excellent clarity Marcus. I'm real glad you wrote this on a Wednesday ;D

[DA_cookie_monstA]

Oooooh, thank you Marcus for that, it is printed out, and I think I may start on it when I get a PSU.

One Question though, how could you fit a switch in there, so you could turn the thing on and off?

[marcoski]

Instead of joining the green wire to the black one permanently, you could put a switch there. Shorting green to black sends a power on command to the power supply, if the green wire is open, the power supply shuts down.

[burgie]

some of the newere PSU's have switches already on them, I believe.

[DA_cookie_monstA]

Chris, I know modern PSU's have got a switch on them too, but, like ANY appliance, I am sure you would soon get really fed up having to reach round the back just to switch them on.

Same with your puter, I am sure you don't switch it on or off by that. Thats why I asked.

[PDW]

DCM - I have a Mac - switch is on the front!!! ;D ;D

Marcus - where can one get a PC Power Supply, what does it look like, what does it cost and what do I ask for? All sounds very good (and well explained) and seems to be a bit better than my 20 year-old (Pegler-made!) power supply and a collection of various old cells!!

Thanks
Peter

[DA_cookie_monstA]

Local computer shop, or, if desperate, PC World, and just ask for what Marcus said, a 400W ATX PSU, and it will come in a box. Warranty WILL be void though for the use we are putting it too.

And a Mac, not an iMac I hope!!!

[Alex Lindsay]

Marcus

What is the purpose of the stop/tail lamp bulb and holder?

[DA_cookie_monstA]

Deleted my reply, as Marcus's reply is more accurate, and makes more sense.

[marcoski]

It acts as a minimum load to stabilise the power supply, they dont like having no load at all. It also makes the output voltages more accurate as the internal regulator has got something to do. You could use resistors, but the lamp is easy to get and does the job well.

[damo]

what sort of amps can you get from this for charging?

[marcoski]

Rather depends on the make, most 400W supplies will deliver up to 20 amps on the 12 volt rail, if you are feeling greedy, the enermax EG651P-V 550W supply is rated at up to 36 amps.

[burgie]

Chris, I know modern PSU's have got a switch on them too, but, like ANY appliance, I am sure you would soon get really fed up having to reach round the back just to switch them on.

seem to have touched a nerve, there, which was totall unintentional. I personally can't think of a reason why you would turn your PSU off at a race meeting though, surely it will always be charging smething?

[marcoski]

LOL for me the act of plugging it in would be a good enough switch, but each to their own....

[DA_cookie_monstA]

Sorry, no raw nerve, but sometimes I get a little abrupt, with looking after 5 kids.

Basically, I would think a lot of people would have it set up at home, so they don't have to bother with using the 12v for charging or doing motor work, so, for most, it will be slung in a box on the work bench/shed/garage. Also, personally, I like the fact that you can shut it sdown by a click flick of an aeeesily accesible switch incase of mishaps.

That better Glenn, I was in a hurry, busy weeks coming up.

[damo]

20 amps ish...cool.....so how difficult is this to actually make???

[Pro_3_racer]

hey guys

i going to make one of these but to save me money would it still work with a 200w ( i can possably get hold of a 300w) power supply as i all ready have a few of these. and to save me money i could use one of these power supplys.

if so what would change on it if anything and what woundn't i be able to do on it.

thanks
Michael

[marcoski]

The smaller power supplies tend not to have enough capacity on the 12 volt rail for our needs. Best to use the one specified.

Damian - its easy - you don't actually have to "make" anything, just a matter of joining a few wires and following the instructions given to the letter.

[damo]

easy even for me huh....ok worth a try as my little 5 amp supply is exactly that little and only 5 amps...lol

[Mark Gilliland]

Bit off the thread, but does anyone know where 2 buy a 6v fan for onboard motor cooling?

[marcoski]

You can buy 5 volt fans from CPC or Farnell - they are not particularly cheap though.

[TimG]

Guys,

I have almost finished converting a 400w psu, I didn't have the 21/5w bulb !!!

Now I have the bulb, I will be finishing it off tonight. I have removed ALL of the unused
wires from within the PSU itself, as this helps to keep things out of the way. If anyone has some spare webspace, or would be willing to host a picture or 2 for me, I will happily email them some photos.

Tim.

[NumanR]

Marcus what size resistors would you recommend to replace the bulb? I hate bulbs!!!

[marcoski]

LOL 22 ohm 25 watt for the 12 volt rail and 6.8 ohm 25 watt for the 5 volt rail. These will get warm, they may need a heatsink, the lamp does not........

[TimG]

I have now finished the psu and it looks GOOD. On top of that, it works really well.

Thanks for the info Marcus.


PM me if anyone has any web space free to host a couple of photos or wants me to email them. The two pics are only 55k in total. - Thanks in advance.

[Pro_3_racer]

there are some pics in the other thread "Mains Charging"

i am hoping to be making mine tonight poviding i can get the psu from school today lol

michael

[marcoski]

Tim's one...

[marcoski]

Thats the last piccy please, post links before I get a load of flack!!! :o

[Pro_3_racer]

hey marcus

is there anything else you can add to it instead of a buld or restiors. I s it possible to put a fan on it so the you can cool things as well as taking the curent off the pack when not in use or would it not work etc.

thanks
Michael

[marcoski]

No, a fan would not be enough load. LOL Just do it as I have said to, and it will be fine. :P

[Pro_3_racer]

ok then kool, looks like im off down the scrap yard tonight to get a buld

thanks
Michael

[webba]

you can get the bulb from a local petrol station or somewhere like that, they are about £1 brand new and would be more reliable than one from a scrappy!

[Pro_3_racer]

oh right ok then i was thinking there were about £6 dont know were i got that from lol

thanks
michael

[Mark Christopher]

scrap yard would be better as you could also get the bulb holder

er escort vans have good ones!! remeber it will be a rear bulb and holder , side/stop lamp or side /fog

[Mark Christopher]

Tim's one...


got to say that looks very neat, bulb is fitted nice, with resisters that would look very professional

[marcoski]

Yeah, neater than mine :o >:( :( ;D :D

[Pro_3_racer]

marcus

i have my power supply but i look nothing like the other ones, there no fan for a start. on it there is only one 4 way plug. there is no 20 way or nothing else. there are 4 other wires white,yellow,white and black.

how would i hook it up and will it still work.

thanks
Michael

[damo]

is that the right sort of power supply??doesnt sound like its a hard drive power supply as they mostly all have a fan on them... :-

[marcoski]

Michael, for the love of God, dont make it any more complicated than it already isnt!!! Please just get the stuff described in my post, and build it as per my post. The solution I have offered you all is cheap enough already!!

[damo]

but cant i just... :-



only messing marcus.....lol

;D ;D ;D

this is the next project i have to do....once ricky sends me my chassis ill get on with building a new bigger power supply... ;D

[Pro_3_racer]

harsh but ok

so i ask and try to do to much, no wonder i get toncelites lol

thanks any way

Michael

a power supply without a fan just means its an older 1, you should check and see if it has high enough watts ;)

[marcoski]

Firstly please complete your profile as per rule 5,

Secondly, I did actually do some research before posting this, and the 400W supply or better are the only ones with enough current to meet our needs.

[Stew Noble]

Off the same harness, pick a red and black wire. This is your 5 volt supply for running your lathe!

On the 20 way connector, pick an orange and a black wire. This is your 3.3 volt supply for bedding in motors

this suggests that you should use 1 wire from the harness to the bolt (or whatever), but in the picture 3 wires go to the bolt, why is this ? which is best?

cheers

stew

[marcoski]

Yep even admins make mistakes!! It will be OK with one wire on each, but the more the merrier, and you would get less voltdrop in the wires.

[gatesy]

Marcus, whats the common wire? My stop/tail bulb has only got 2 wires on it!

[damo]

good question as the bulb i bought doesnt even have wires on it.....so where am i sposed to solder to people...??

[marcoski]

LOL your are all blokes, you are supposed to know these things - the common connection is the metal case between the base of the lamp and the glass!!

[damo]

its me marcus..i only just learned about fuses remembe..light bulbs are way to difficult for me...lol

[marcoski]

ROFLOL - yeah I remember that ;D If you look on page three of the "charging from the mains" thread, the first picture I posted shows the connections to the lamp. Save the pic to your desktop and look at it using a photo editing program, you can zoom in on the lamp to see the connections.....

[damo]

yeah i got that now....cheers matey....was kind of curious is all, all i got to do now is actually get round o building it....keep sniffing for the smell of burnt fat bloke and stories of spontaneous combustion in the near future..itll be me... ;D :-[ :-X :'( ;D

[marcoski]

LOL you can get "a round toit" from most good hardware stores these days, so there is no excuse!! ;D ;D

[damo]

you dont know my missus... :-

its a valid excuse mate really.... ;D

it will be done sort of by the end of january..at least when xmas is gone ill have the time and wont be made to go shopping everyweekend >:(, or wrap pressies when i get home from work :'(...

[gatesy]

LOL your are all blokes, you are supposed to know these things...
I'll blame it on being colour-blind ::) Did make the wiring kinda tricky!! :'(

[Team Tamiya]

hi, you say you can replace the bulb with 22R and 6R8 resistors with a 25W power, am i right in thinking that as long as its more than 25W the power rating wont matter?

Reason being i am thinking of using HS50's from RS (codes are 160-922 and 158-345), they dont seem to do the 25W in a 6R8 value.

[marcoski]

Yep, they should be fine.

[Stu_Dale]

I dont mean to pick falts, but shouldnt you add a capasitor to the plus and minus output terminals, to protect the psu and your charger, from voltage spikes when they are conected?
please corect me if i am wrong.
Stu.

[marcoski]

There are more than enough capacitors and other decoupling measures in the power supply to provide adequate protection against this. Also the supplies come with comprehensive overvoltage protection built in which will automatically shut down the supply safely should over voltage occure. Besides, I have never seen capacitors used as an extra measure when connecting to a wet cell or a mains power pack.

[Stu_Dale]

Ok, it was just something i had seen on a diferent walk trough to convert one of the non atx style power suppys.
Stu.

[John Stones]

me and me dad use a couple of power supplies used for HP laptops. jus chopped the connecters off and put deans ones on instead

[marcoski]

Thats a rare find indeed, most laptop power packs give 18 volts at around 3 amps or so, to find 12 volt ones is remarkable - all credit to you :)

[Nick Hudson]

i have built a power supply to the exact letter of the instructions and found the following :-

1. the 12V supply drops to 11.2-11.3V under a 5.5A charge load (as measured by my LRP Pulsar charger) - it does still charge though albeit only just
2. the 5V supply measures 6V
3. the 3.3V supply measures 6V aswell !!

what am i doing wrong ??!! :-

nick

[damo]

possibly the wires to the 12 volt supply are not all there and one might have been put to the lathe/motor run in supply??..ill be quiet now and let marcus tell you...

[marcoski]

i have built a power supply to the exact letter of the instructions and found the following :-

1. the 12V supply drops to 11.2-11.3V under a 5.5A charge load (as measured by my LRP Pulsar charger) - it does still charge though albeit only just
2. the 5V supply measures 6V
3. the 3.3V supply measures 6V aswell !!

what am i doing wrong ??!! :-

nick


When you cut the orange cable(s) from the 20 way plug, did you leave a thin orange wire all on its own? This thin orange wire needs to be connected to one of the thick ones. The thin orange wire is the 3.3volt sense wire and is used to regulate this supply.

[damo]

i was almost right..i think..and its a monday...im impresed with myself...

[Nick Hudson]

that might explain it....

any idea on the lower 12V reading ??

[marcoski]

You should find that once the 3.3 volt rail is where it should be that the 12 volt rail will recover. Bear in mind that the 12 volt rail will be 12 volts, and if there is a reverse polarity protection diode in the pulsar, it may read about half a volt low.

[Nick Hudson]

thanks marcus - i unfortunately chopped off all the extraneous wires for neatness so will have to trace the thin orange wire back inside the case and splice a new length on....!

nick

[marcoski]

LOL I should have made that clear, its amazing when you write such a story how many little things slip through the net, just because I know it has to be so and forget to add it!!

[Nick Hudson]

no worries - its been ages since i hacked away at such a job - my kitchen table looked like dr frankenstein's workbench by the time i'd finished !!

guess who's soldering tonight ? :D

[tom_goodyear]

Ive got a 350W ATX power supply from my old case, will this be enough to power a charger?

[damo]

aaaarrrrrrrrrrggggghhhhhhhhhhh dont make things any more difficult...use a 400 ....lol....possibly but i dotn think you will be able to do all the lathe and motor run in at the same time...MMAARRCCUUSS help please ;D

[Nick Hudson]

You should find that once the 3.3 volt rail is where it should be that the 12 volt rail will recover. Bear in mind that the 12 volt rail will be 12 volts, and if there is a reverse polarity protection diode in the pulsar, it may read about half a volt low.


it works (funnily enough !) - the 12V output is approx. 0.5V over what the Pulsar says but still 'only' 11.7V. having dug out the thin orange wire, the 3.3V rail is spot on.

works like a good 'un though

[tom_goodyear]

Hi, my 350W power supply states 15A on the +12V so I assume this will be enough for my charger. The power supply has a 4 pin connector for certain motherboards (pentium 4 i think) and the wires on this are red and black (+12V and 0V?). Shall I join these up to the other yellow and black ones for the 12V aswell?
Thanks

Tom

[marcoski]

You should measure the voltage here first, most power packs give 5 volts on the red wires. If it is 12 volts, then join away...

[tom_goodyear]

argh! just realised i put red and black, should have been yellow and black! Hopefully I will get a bulb some time in the week then I can test it out ;D

[marcoski]

LOL easily done! If they are yellow then yes you can join them with the others.

[gary1208]

Hi, I've just found a pc psu in the shed.It doesn't show the wattage but it has a sticker giving the amps for the different voltages
5v=30amp
3.3v=14amp
12v=12aamp

Would this be man enough for the job?

[marcoski]

It should be, give it a try. If it can't cope, it will shut down safely to protect itself.

[DA_cookie_monstA]

Right, just for Marcus, I done my PSU, found a cheap and neat way to carry it about and protect the connectors to it. A Hard Case from B+Q, really cheap, and there is room in there to store me charger and lathe too, brilliant.

Now, all I got to do is work out where to put the remaining wires too.... lol

[KeithA]

Marcus/Chris,

I while back you were discussing using 2 resistors instead of a bulb. To connect this up, following the step where you join the green and one of the black wires together from the 20 way long multi-plug would you:

Pick another black wire, cut it and connect to the +ve on the 22R resistor and also the +ve on the 6R8 resistor. Then pick a red wire out and connect to the -ve on the 22R resistor. Then pick a yellow wire and connect it to the -ve on the 6R8 resistor. or would you:

Pick another black wire, cut it and connect to the -ve on the 22R resistor and also the -ve on the 6R8 resistor. Then pick a red wire out and connect to the +ve on the 22R resistor. Then pick a yellow wire and connect it to the +ve on the 6R8 resistor.

Also what would you advise mounting the resistors onto?

Sorry to sound dumb but I've just started reading my electronics made simple book by Ian Sinclair!!!!!

Your help is appreciated.

thanks,

Keith.

[marcoski]

LOL neither!

The 6R8 resistor is to load up the 5 volt rail, connect a black wire to one end, and a red to the other.

The 22R resistor is to load up the 12 volt rail, connect a black wire to one end and a yellow wire to another.

There are plenty of black wires to play with, you can afford to use two separate wires, one for each resistor as described above, makes for easier wiring and mounting.

You will need to mount them on a heatsink, a black plate of aluminium with finns on it. This heastink and resistor assembly should be so mounted that one of the fans on the PSU is either sucking or blowing air over the finns, to keep the heatsink cool.

[KeithA]

thanks Marcus. That's just what I was trying to explain!

Does it not matter which end the black red/yellow wires go on each resistor.

I think I need more text books....

thanks again,

Keith.

[marcoski]

No, it does not matter at all, resistors do not have a polarity, since they are effectively a piece of high resistance wire.

A really good textbook in electronics, which will provide a broad grounding in an easy to read / understand format is "Success in Electronics" by Tom Duncan, ISBN 0-7195-4015-1.

[KeithA]

Excellent, thanks for the recommendation Marcus. I'll keep on trying.

[KeithA]

Marcus/Anyone,

Just 2 quick questions on the Power Supply?

I am at the stage whereby all my connections are done and I'm just going to tidy up the wiring, can I snip short all the remaining wires and heatshrink/insulate them together so long as they are the same colour, ie. all the orange wires, all the red wires etc. or do I need to insulate each wire individually? I'm guessing I can group them together by colour.

Secondly, I have mounted a 5v LED (sad I know!), can I just pick off a red/black wire from the 20 pin connector to power this?

Thanks again for all the info - its been very interesting....

[marcoski]

Yes you can do all of the above. Just make sure that the thin orange lead is still connected to one of the thick ones. This is important.

[KeithA]

Marcus,

Thanks again, Do you know of a web link that shows just out of interest what all these wires do, ie. the purple/grey/sky blue ones etc that I haven't used at all?

I promise I won't ask any more questions....lol

cheers,

Keith.

[marcoski]

No, but as you asked....

3v3 orange
5v red
12v yellow
0v return black
-5v white
-12v blue
5v standby (always on) purple
power good grey
power on signal green

[justinbowness15]

marcus can you write a brand new post with all the corrections on. likr that people are encoutering, please!

because i am only a beginer in electronics and if something goes wrong ive had it, can you find a link on the web for me where i can buy a psu really cheap because my livelyhood if sponsered via a paper round so ... you know!

thanks, this would be very good of you

[marcoski]

They can be had from the following link on ebay.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=3451621583&category=36 70

As for gathering up all the data into a new story, you might want to get issue 10 of the rcracenews magazine when it comes out....

[KeithA]

Hi all - just finished the PC power supply conversion with loads of advice from Marcus and safty/testing advice from my brother...... It all works really well and for under £23 with resistors and connectors it works out very economical and it is ultra quiet and I think it looks v. good too!!!!

http://uk.msnusers.com/KEITHANDER/psu.msnw?Page=1

Marcus - I think our efforts deserve a pic in the latest issue of the on-line mag?

[Coppins999]

Justin,

I've just ordered this one from ebay after looking over xmas period (bit too technical for santa, but gave me the money :-) )

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=3451513033&category=36 70&rd=1

This shop seems to advertise regularly and as you see they were selling 18 at the time auction finished. Although a little dearer, free postage makes a tidy saving of nearly a weeks deliveries ?!?!?

Marcus - hope I've ordered right item with this one?

Haven't received the unit yet, but if you want, I can let you know if it works OK in a week or so.

James

[justinbowness15]

that one you recommended on ebay is good but add postage £6!
is that other one that kieth recommended on ebay good will that be ok

thanks

justin

imagine how many people you have helped! look at the times read

[justinbowness15]

sorry i ment james, where can i but rcracenews?

[marcoski]

LOL you see that big advert at the top of every page? Try clicking on it........

[Robracer]

I have just bought a 550W PSU frm my local computer shop.
So before cutting and destroying the harness, I thought I would test for the 12V & 3.3V outputs but the PSU will not give a 12V output so far, it only shows the 3.3V output.
Can I assume the PSU only works correctly when the entire job is done, then the fans will work, because at the mo, the fan's don't even acknowledge that they have a power supply from the mains.

Some help would be very much appreciated.
Thanks.
Rob.

P.S, I only want to test it so I know it works before cutting harness, as not void the warrenty yet.

<complete your profile and I will answer your Q>

[turbotim]

hi,

how reliable are these psu`s ? only later this year ill be going to the belgium gp and while there i will have the power supply on constant roughly 10hrs, charging on two chargers with soldering iron on. although they wont all be charging all the time the power supply will still be on for that sorta time.

[marcoski]

My PC has been on non stop for the past 6 months (honestly, I never turn it off) and it runs one of these 400W power packs, they are exceptionally reliable. Most work PCs will do a twelve hour shift without complaint.

[turbotim]

great will be out to get psu tomorrow. and gonna go for resistors rather than bulb. found some on rs site but are 50w not 25w i would guess as in past post that it dosent matter so long as they are higher than 25w?

[marcoski]

50 watt would be OK, should dissipate the heat better, though you may still need to bolt them to a heatsink of some sort, depends on how hot they get.

[turbotim]

hi marcus,

have done psu, fitted it all within original case. very small, very cheap and very quiet. beats anything you can get from a model shop by a long way.
added costs up came to a grand total of £26.00

cheers

tim

[marcoski]

I have just bought a 550W PSU frm my local computer shop.
So before cutting and destroying the harness, I thought I would test for the 12V & 3.3V outputs but the PSU will not give a 12V output so far, it only shows the 3.3V output.
Can I assume the PSU only works correctly when the entire job is done, then the fans will work, because at the mo, the fan's don't even acknowledge that they have a power supply from the mains.

Some help would be very much appreciated.
Thanks.
Rob.

P.S, I only want to test it so I know it works before cutting harness, as not void the warrenty yet.

<complete your profile and I will answer your Q>


You need to link the green and one of the black wires on the 20 way plug with a piece of wire. This will switch on the PSU and start the fans. You should connect the load before doing this.

[Robracer]

Thanks for the answer Marcus, I went ahead with the alteration that day, and hey presto it worked first time, I then cut all the unused wires off the board inside to tidy things up, the only job I have left is to change all the nessecary wires that are being used for some nice 36amp rated black/Red wire and some nice connections from my local but useless electronics shop.

Thanks for the instructions.
Rob.

Now I don't have to lug around a damn heavy leisure battery to every meeting.

[DA_cookie_monstA]

Evening chaps, got a question for you.

My PSU works fine if I am running a single charger of it, but, the PSU 12v rail rating should EASILY take two chargers and a 12v iron too, so, heres the question. If I hook up the second charger, the voltage drops too far, if I put a load on the 3.3v rail (i.e. a motor), it works fine.

Now, I am running the stop/tail lamp version, how do I increase the laod that is seen by the Power Supply?

[marcoski]

Get a 55/60w head lamp bulb, and run both filaments at once on the 3v3 rail. That should keep it happy.

[DA_cookie_monstA]

Thanks Marcus, I think I got one of them knocking around somewhere too.

[turbotim]

is it possible to ramp the volts up on the 12v rail ie from 12v to 13.8v?

[marcoski]

No. The over volts protection will declare a foul, and most PSUs nowadays do not have adjustment pots for the output voltage.

[AndyT]

Just to let people know, or maybe advise. Dont buy cheap PC power supplies, just aint worth it. Being a bit of a PC guru I can recommend this company for the quality of their supplys. They do a whole host of PSUs going upto 28A outputs on the 12v rail :o. Anyhoo heres the one I ordered, it's cheap but it'a quality also. :

http://www.overclockers.co.uk/acatalog/Online_Catalogue_Q_Tec_139.html

and just FYI, heres a pinout for all the wires in modern PSUs :

Sorry it's a bit big 200k, but you can save and print and keep for reference if you wish :)

http://www.andythilo.fast24.co.uk/images/pinout.jpg

Hope this helps some people.

[justinbowness15]

which wattage one should i buy and is it capable for what we are going to do with it has anyone got any pics of a completion with this psu

[marcoski]

Justin, please read the thread from the beginning, and you may wish to read the thread "Charging from the mains" as well. There are several pictures in these threads and full instructions as to what to buy and how to do it.

[justinbowness15]

so wont that one on the link be ok, i dont understand ???

;D sorry?

[marcoski]

Andy T points to a 400 w supply, which is what I stated in the very first post. READ IT

[justinbowness15]

i have read it! >:( ;D

will it be in rc news issue 10, the info
is there anywhere i can buy a ready made one?( i no it will be more)

and i will only want to use the supply for a charger, can i leave all the other bits, motor and lathe bits?
thanks

[marcoski]

I am writing the story as we speak.....

[justinbowness15]

do you write for the magasine then?

[marcoski]

You will find one of my stories in issue 9...

[AndyT]

Justin, you can choose any one you like, the lowest is the 400 so that will be more than capable for your needs, you could spend the £25 and get the 550 version is you wanted to run more stuff. The 400 is the minimum that has been recommended in this thread, and I believe that is what most people are getting. I went for the 450 personally. They do plenty of others to suit your budget, upto about £80 I believe, but for our purposes this is bit of an overkill.

[sam c]

anyone got any pcitures of there cahrger lathe and motor running off this??

[marcoski]

LOL why, don't you trust me? ;D

[Dave G]

ive been using one for ages now for running both lathe and motor..if your not 100% sure then dont make one or purchase a 12v supply from your local electronics shop.


cheers
dave

[sam c]

i believe it works only just my dad doesnt see how :'(

[AndyT]

What do you mean he doesnt see how?. A Lathe motor runs off DC voltage, not sure what as I dont have one, but i'd guess the same as a batt pack so 7.5v. Now to get near this off a PSU that is talked about here, just connect the motor+ to +12v and the motor- to +5v, this will give +7dc into the lathe motor. Or run it lower at 5v or 3.3v, all which are available in this PSU.

p.s please correct my voltages if i'm wrong, as I say I dont have one and am new to all this ;D

[marcoski]

LOL - when its inside a PC, all the rails are loaded up at the same time, its no different to running a lathe, motor and charger at once. I dont have a 12V charger, but I do have a 1 ohm resistor, which will draw 12A from the 12 volt rail, motor an lathe there too. 1 ohm resistor is the gold bar in the pic. This is all running off a 400W power supply from overclockers.

[marcoski]

Now to get near this off a PSU that is talked about here, just connect the motor+ to +12v and the motor- to +5v, this will give +7dc into the lathe motor.



You cant do that - power must be taken with respect to ground (black wire), not another rail.

[AndyT]

Well you can with fans, as that what is the norm for getting a 12v fan to run at 7v and be nice and quiet, and works a treat. Try it!. I just assumed that i'd work with a motor too.

[marcoski]

You can with fans, because the load is minimal, and the load of the PC will hold the rails stable. If you try it with a lathe, on an otherwise unloaded supply, the 5 volt rail will be pulled up by the 12 volt rail and the supply will shut down because of over volts on the 5 volt rail. The rails on these power supplies are designed to source current, and have no ability to sink it. Its only because of the PC load that the fan trick works, the PC acts as a current sink for the 5 volt rail.

And before you ask, I tried it, and it shut down.

[AndyT]

Ahh ok, fair enough! ;D

Sam, dont use my 7v mod trick!

[AndyT]

Thought i'd show you my effort. Top sockets are for 12v, 5v and 3.3v. Blue LED is just to show power is on. The screws on the side are where the resistors are. The side gets warm, but I used some thermal compound so the whole side acts like a heatsink for em. I'm gonna fit a switch on the front where the hole has been left from the cable loom.

http://www.andythilo.fast24.co.uk/images/psu1.jpg

[Dave Treacy]

Hey Marcus!

Clean that workbench man! It looks like a tip!

And to think my ESC's have been serviced there..... ooooh, I feel all dirty ;D ;D ;D

[LisaKeen]

Dave, that is actually quite a clean bench, by his standards ;D :D ;D :D ;D :D

[chrislee]

He's a typical sparky :D

[marcoski]

ROFLOL - It IS tidy - cheeky beggers ;D ;D ;D

[Doomanic]

A tidy desk is an unproductive workspace!
If you have time to keep it tidy, you're not working hard enough!

[Doomanic]

AndyT, that's a nice job, wanna do mine! ;D

[Doomanic]

Marcus, what's the green labelled box on the left?

[AndyT]

AndyT, that's a nice job, wanna do mine! ;D


No probs, for a price ;D

[marcoski]

What, you mean the box lid off the handset charger, or the halfords box?

[Doomanic]

Oh right, now I remember, it's been a while since I saw it last! ;D

[pete c]

I have been reading this thread for weeks and I have just got the P.S.U delivered together with the all the other bit I will need. I am sure I can follow your instuctions and end up with a P.S.U. that dosn't blow when I use my 12volt iron :'(.
The only question I have is do I have to discharge the caps in the P.S.U. and if so how :o??

Thanks
Peter

[AndyT]

Dont touch the caps directly. It's normally a good idea, but tbh I wouldnt worry. You will only get a problem if you start ramming a screwdriver round inside it!. If you want to be double sure, this is what i'd do, probably be corrected by Marcus but here goes lol. Get a 12v comp fan and connect it up to the PSU. Make a little jumper wire to short out the green and black wire in the big connector block coming out of the PSU, this will turn it on. With the mains connected and the fan, put this jumper in. The psu should power up and the fan spin. Remove the jumper, then turn the mains off at the wall, dont unplug it. Allow the fans to spin down, then put the jumper back in, any charge held by the caps should discharge saftly through the fans, you may see em turn a little.

<--- waits for Marcus to come and tell me i'm talking outta my botty ;D

[DA_cookie_monstA]

What, you mean the box lid off the handset charger, or the halfords box?


That lid looks REALLY familiar to me, it looks very similar to something a friend of mine developed a long time ago, filed charger for a transmitter, made by Bobtech.

[marcoski]

With regard to the caps, they have discharge resistors across them. Unplug the unit from the mains then wait 10 minutes. The unit will then be safe to play with.

[pete c]

Thanks for the info, I can now play safe without been blown to the other side of the workshop(bedroom) :-X

[rbecking]

I built one of these PSU's a few weeks ago and it's been great, I've been using the 12v to power my charger and digital discharger and been using the 3.3v to run in motors.

Today though I connected the 3.3v leads to a motor and the motor turned for a fraction of a second then the PSU powered off. I turned it off and on a few times and it does it each time but the 12v still works fine, whats wrong with it?

[marcoski]

The power supply is shutting down because you are asking too much from the 3.3 volt rail. What sort of motor is it?

[pete c]

Marcus
I have just built the unit to-day, using resistors inside the case and all wires cut back and made neat inside as well.
I have a few questions if you don't mind?

1/ My 12volt output to the charger is 11.85 volts I have charged at 7amps and it works fine is this o.k.? ( I normally only charge at 5/6 amps)

2/ I have a 50 watt 12 volt iron from A**X Models, how many amps will this draw and could I use it at the same time as the charger?
On the P.S.U. it states that the 12 volt rail is 12a con/16a peak.
Thanks Peter

[Mark Christopher]

4.1 amps watts/volts = amps

amps X volts =watts
watt /amp = volts

[pete c]

Thanks Cartman
It's a long time since I was at school :D

[rbecking]

Trinity Monster, I thought you said in the instructions that the 3.3v is ok for running in motors?

[AndyT]

Certainly should be ok. I ran mine into at a meet after having the comm lathed. Did it twice in fact. Have you made sure that you connected the thin orange wire with the rest of the orange wires?.

[marcoski]

Re Pete C. Yes this is fine. The 12 volt rail is rarely 12 volts exactly - on some its a touch low and on others its a touch high.

You should be able to run both the iron and the charger, given your normal 6 amp charge, total current would be around 10.5 amp.

[rbecking]

I've been using just one of the orange wires from the big block and one of the black wires. Do I need to use them all? It has worked fine for a couple of weeks. Is the small orange wire on the big block aswell?

[marcoski]

Re rbecking - yes the 3.3 volt rail is OK for running in motors. Mine will stand a 12 double with no issues. It does depent on the current rating of the 3.3 volt rail, having bought several power supplies recently from various outlets, some 3.3 volt rails are stronger than others. One supply I bought was only capable of 14 amps, whilst others are capable of 20 or more. Most power supplies are much more capable on the 5 volt rail, if you find a particular motor is too much for your 3.3 volt rail, use the 5 volt one instead. Or, you could limit the inrush current with a resistor, you could make up a lead with one or two mardave speedo resistors in it to limit the current.

<edit> use all of the orange wires together, and as many blacks as you use orange - try this first >

[AndyT]

I've been using just one of the orange wires from the big block and one of the black wires. Do I need to use them all? It has worked fine for a couple of weeks. Is the small orange wire on the big block aswell?


Yes it is, make sure you connect this with the other orange wires. It's some kind of sense wire thingy, it's been explained already somewhere in this thread by Marcus. Like the man says try and use all the orange wires together. Pulling max current through just one wire aint a good idea. On my supply there were 6 thick and 1 thin orange wires. 2 were on a different plug, but they all come from the same place in the PSU!.

[Colin Williams]

Right, I've got all the parts now, and I going to start the conversion soon. But I was wondering whether it would be OK to take two of the yellows to one 12v socket, and the other two to a second 12v socket (along with 2 black's to the -ve's on each) so I can plug two chargers independantly?

Thanks,

Colin

[AndyT]

You should have more than 4 yellow wires. Try to use as many as you can, just make sure that the current rating of both chargers doesnt exceed the current rating of the PSU. Also try to keep all wires as short as possible, the PSU will not put out more than 12v generally so any volt drops due to wire lengths will be significant. From reading other posts some chargers are quite picky when it comes to the 12v level.

[rbecking]

Just tried it with 5 orange/black wires each and it seems to work ok. See how it goes, should I be able to use the 3.3 and the 12v charging at the same time? My PSU says 12v is 15A and 3.3 is 14A. My charger charges at 5.5A.

[marcoski]

Yes

[Colin Williams]

You should have more than 4 yellow wires. Try to use as many as you can, just make sure that the current rating of both chargers doesnt exceed the current rating of the PSU. Also try to keep all wires as short as possible, the PSU will not put out more than 12v generally so any volt drops due to wire lengths will be significant. From reading other posts some chargers are quite picky when it comes to the 12v level.


Thanks Andy, I take it I can connect the way I suggsted then - i.e. split the yellows accross two plug sets? Just checked and there are definately only 4 yellow wires.

Colin

[AndyT]

It suprises me there are only 4 yellows on a modern PSU. Anyhoo, i'd say try it and see. Your not gonna do any harm to the PSU or to your chargers. If the current demand is too great all that will happen is the PSU will cut out. Try it and let us know.

[tc3Adam]

I went by your instructions at the beginning of this thread, I am using a 450watt ATX ps.
When I connect my Pro Peak SuperNova charger sometimes it is fine, other times is false peaks at half charge using 3amps or 5amps with 3300 batteries
Could this be the power supply or a fault with the charger. It is not the batteries as they peak ok with my other mains charger.

Also I seem to remember in an earlier post that you can use the outputs together but if I connect to the 12v and then draw off of either of the other lower output, the power supply cuts out.

If the problem is the charger, any idea where to send it in UK for test/repair.

[cobra81li200]

Markus,

I haven't read all the thread, obviously I'm not really interested as I'm using a modified PSU since 3 years now (not modified as you did, mine has been modified by an electrical engineer).

From what I've seen, you do not tell to be careful with the capacitors. But any maintenance on a PSU should be preceded by a discharge of the capacitors, or you may face very high voltage residual current.

THIS IS VERY DANGEROUS !!!

I know I'm going to be told it's not my problem, but would you not be a professional, you should not open a PSU AT ALL ! There is a good reason if danger flags are present on the box of a PSU.

Please if you want to use such a PS, then ask a real pro to do it for you.

[marcoski]

And just where in my instructions does it say to open the power supply - er nowhere! Infact I specifically forbid it and it is not necessary. I have been an electronics engineer for 15 years and I know the dangers of going inside the PSU. However, if you were in the trade too, you would also know that it is MANDATORY to provide discharge resistors across mains reservoir capacitors that render the unit safe to touch within 5 minutes. Also, as all PSUs use two 250 volt caps to enable 110 volt use, they need voltage balancing resistors across them anyway, again serving to discharge them to a safe level within 5 minutes.

I strongly recommend you do your research and get your facts right before publicly taking me to task over such an important issue.

[cobra81li200]

However, if you were in the trade too, you would also know that it is MANDATORY to provide discharge resistors across mains reservoir capacitors that render the unit safe to touch within 5 minutes.

I didn't know that indeed, maybe on my 'old' PSU it was not the case and that's why the guy that modified my PSU told me to be really careful.

[AndyT]

Just one other thing, modern computer PSUs have a plastic sheet of the back of the PCB, not only to stop the pcb touching the chassis, but to stop fingers getting to the PCB.

[KeithA]

Yep even admins make mistakes!! It will be OK with one wire on each, but the more the merrier, and you would get less voltdrop in the wires.


Marcus, I take it that if you use all the same colour wires from the different connectors thats ok? ie. you can pick red or black or yellow etc from the 20 pin and/or 4 pin connectors as all the colours themselves are the same voltage regardless of which connector block they come from?

[tc3Adam]

Sorry for repeating this query, but I was hoping for some comment

I went by your instructions at the beginning of this thread, I am using a 450watt ATX ps.
When I connect my Pro Peak SuperNova charger sometimes it is fine, other times is false peaks at half charge using 3amps or 5amps with 3300 batteries
Could this be the power supply or a fault with the charger. It is not the batteries as they peak ok with my other mains charger.

Also I seem to remember in an earlier post that you can use the outputs together but if I connect to the 12v and then draw off of either of the other lower output, the power supply cuts out.

If the problem is the charger, any idea where to send it in UK for test/repair.

[marcoski]

The pro peak is a pulse charger, the power supply will not be too happy driving a pulsed load. You can try a large power cap across the 12 volt rail to help smooth out the pulses.

Edit - can I add that you should not pulse charge NiMH cells, only linear charge.

[tom_goodyear]

Ahh that would probably explain why my PSU doesnt power my Schumacher CCD20 very well then! (For those who don't know, CCD20 is quite an old NiCd pulse charger/discharger).
Marcus, what value capacitor would you suggest to use for the 12V?

Thanks

[marcoski]

4700uF at 16 volts or more.

[tom_goodyear]

Thanks ;D

[pete c]

Marcus
I have dropped a clanger with the P.S.U I have converted.
I read 6R8 as 68R and this is what I have put in :- :-
I will change this next week.
On friday I was charging my cells and they dumping after 3mins of racing is it because of the wrong resistor.
You dont know how stupid I feel
Peter

[AndyT]

The only difference that will make is that it will draw less current, approx 73mA as opposed 730mA with the 6R8. And remember this is off the 5v rail and is only to provide a bit of load to stabilise it, so will have no effect on the 12v rail. I cant see how this can have any effect on your charger. May be that your cells have some memory effect and need some good discharging/charging cycles to get em working good again.

[pete c]

Thanks for putting my mind at ease, I have some new cells on order, my old ones are a bit passed it.
Thanks again
Peter

<Peter, please display your full name as per rule 5, thanks>

[AndyT]

You may want to wait for Marcus to reply as he may slap me round the head and tell you i'm talking rubbish lol, but i'm pretty sure i'm not.

See if you borrow a m8s discharger and you may be able to get them good again.

[marcoski]

LOL Andy , yes and no! With most power supplies, the 5 volt rail is used to provide feedback for the regulator, the 12 volt rail is nominally 12 volts because of the ratio of the windings on the transformer. If the 5 volt rail goes wandering off, the 12 volt rail will follow suit! So it would be wise to obtain and fit the correct resistor.

However, I do agree that it is most likely that the cells are past it.

[AndyT]

I thought that as these are switched mode psu's they have a separate high freq tranny for each voltage?

[marcoski]

With most PC power supplies, there are 2 high freq transformers. One to generate the standby 5 volt rail, and the other larger one generates the rest. The 5 volt rail provides the principle regulation, the 12 rail follows this closely by the method of transformer construction. The -5 and -12 volt rails are generated from higher initial voltages and regulated using 3 terminal linear regulators. The 3.3 volt rail is regulated using a switch mode post regulator, and is independant of the 5 volt feedback system, using its own feedback via the thin orange wire.

[AndyT]

Ahh glad thats all cleared up then ;D

[Doomanic]

My power supply (450W) drops to 11.7v under load.
Is this normal?

[marcoski]

It is. DCM in da LAB reported this issue, and found that by loading the 3.3 volt rail, his 12 volt rail recovered some of its output.

[DA_cookie_monstA]

Yeah, Doom, leave a motor running on the 3.3V rail, and you can run two chargers at the same time ;D;D;D or you can just use a more powerfull bulb....

At the mo, I got a halogen headlamp bulb to go in, but I have got access to some Aircraft landing light bulbs if I need ;D;D

[Doomanic]

The chap that built mine (yes, I am that lazy! ;D) used resistors rather than bulbs.
I will ask him what rating he used and go from there.

[DA_cookie_monstA]

I think, if I am going to run two chargers I will just run two power supplies, much simpler.

[Doomanic]

That was with only only one Pro-Trak charging and the other discharging.

[DA_cookie_monstA]

With mine, as soon as I started to charge on the second charger, the voltage would drop and the Eagle charger would stop charging, then the other owould carry on..... I got the bulb, might as well try...

How did you say to wire up the Halogen bulb again Marcus?

[Muria ninja]

LOL LOL ;D

<Please show your real name in your profile.>

[marcoski]

With mine, as soon as I started to charge on the second charger, the voltage would drop and the Eagle charger would stop charging, then the other owould carry on..... I got the bulb, might as well try...

How did you say to wire up the Halogen bulb again Marcus?


To provide a reasonable load, run both filaments together.

[DA_cookie_monstA]

Going to sound stupid this, but which voltage rail do I connect the the Halogen bulb then Marcus?? Do I connect both to both fillaments, or one voltage rail to both, if so, which.....

Sorry Marcus.

[AndyT]

Marcus, how much current do you think a standard 27t motor will draw from the psu running off the 3.3v rail?. Reason I ask is that a couple of times last night, and for the 1st time, the psu shut down when I was trying to bed some brushes in. Never happened b4. Just wondering if the initial kick of the motor starting is drawing too many amps for the 3.3v rail. What do you think?

[marcoski]

Going to sound stupid this, but which voltage rail do I connect the the Halogen bulb then Marcus?? Do I connect both to both fillaments, or one voltage rail to both, if so, which.....

Sorry Marcus.


Both filaments together on the 3.3 volt rail, as you suggested yourself using a motor.

[marcoski]

Marcus, how much current do you think a standard 27t motor will draw from the psu running off the 3.3v rail?. Reason I ask is that a couple of times last night, and for the 1st time, the psu shut down when I was trying to bed some brushes in. Never happened b4. Just wondering if the initial kick of the motor starting is drawing too many amps for the 3.3v rail. What do you think?




Running current won't be very much, but the inrush when it is first plugged in may be just too much.

[AndyT]

Hmm thats what I thought too, strange that it's just started doing it. would a cap reduce the in-rush?, or maybe a pot to slowly bring the voltage (and hence the motor) upto 3.3v.?

[marcoski]

A cap across the rail may help, can't see how you can use a pot though. An alternative is to use a mardave speed control resistor in series with the motor to limit the inrush current.

[Moschops]

What an excellent idea, I never realised PC power supplies could deliver so much current. In fact I was so impressed that I immediately ordered the 400w twin fan ps from OC and i've just converted it.
Only small problem is I managed to trap the orange sense wire under one of the board fixing screws and the next thing were smokin'! glad I fitted a switch...

Just waiting for the caps to empty before fixing it. ::)

Nice work Marcus 8)

Edited to add:

The short didn't hurt anything and it's working really well. I put the connectors on the sides in case I wanted to use it as a stand for my car but thinking about it i'd probably drop a clip or screw inside it! :o

Here's a couple of pics:
close-up (http://moschops.hayesfarm.co.uk/rc/pc_charger_5.jpg)
all running (http://moschops.hayesfarm.co.uk/rc/pc_charger_3.jpg)
Interestingly my KO charger reports the input voltage 0.5V lower than it is. ???

[AndyT]

Made a few alterations to my PSU, just for added bling bling ;D

http://www.andythilo.fast24.co.uk/images/psupurple.jpg

p.s it is purple, just shows up blue on the digicam for some reason ???

[Ben Turner]

Fair Doos mate, that looks waaay better then any power supply ive seen. :D

Ben

[justinbowness15]

whats the biggest ampage ( if thats a word) the power supplies can give out?

[AndyT]

Depends how much you wanna spend, anything from 10 to 40amps. The one I've got kicks out 12A @ 12v which is plenty for my needs. If you wanna run 2 chargers you may wanna go upto 20amps.

[justinbowness15]

thanks

[ninjagordy]

you can get the q-tec 550w (25a) supply for £32 at www.kustompcs.co.uk

;D

[kevinb456]

ive decided ill have a go at this :D ill get the bulb from my motorsave over the road 2morro and then a PSU sometime in the week, gonna be cool :D

[justinbowness15]

hey guys
im thinking of making one of these psu's
can u tell me where i can buy a psu good one, link to website not silly money
i work at a garage so the bulbs not a problem, anything else

so how many people of here have built a psu

what problems
i going to run a lrp pulsar competition of it eventually

[AndyT]

Either the link mentioned above, or http://www.overclockers.co.uk

The only fall back to this type of supply is the 12v line can get a bit low. Whereas a normal 12v power supply will give out 13.8v roughly, these will only give out 12v or slightly lower. There are some psu's about that have pots in them to adjust the 12v rail but only by +/- 0.3 volts say.

I personally havent had a problem with mine, although the charger I use (space charger) very occasionally complains of a low 12v rail.

TBH unless you need the 3.3 and 5v supplys, get something like the new schumacher supplys which are very good and as you say you are gonna use the LRP which has motor run-in on it, you can use that for motors and lathes.

Hope that helps

[justinbowness15]

have you seen the psu's on the top models website
they have some but dont know weather they are very good

is the schumacher one very big and heavy i think it is

i want a small and light one

[AndyT]

The days of heavy psu are gone m8. The new switched mode psus are very light as they dont use the big heavy transformer that old psus use. I couldnt tell you how much the schumacher one weighs, but i'll guarantee it's quite light. Just pick up someones computer psu and see, and they chuck out more far more amps.

[joebraces]

i went on www.ebuyer.com and typed in 400W ATX PSU and something came up but it just looked like the case of a pc i am not sure what a 400W ATX PSU is is it the case of my pc if not can u give me a website where i would be able to see a pic of one thanks

[joebraces]

i now no what one is are any of these suitable http://www.overclockers.co.uk/acatalog/Online_Catalogue_Q_Tec_139.html

[justinbowness15]

im worried of the computer psu going wrong , elctricuting me and having the error low imput messages keep coming up

[AndyT]

I see what you mean. This is what you want :

http://www.ebuyer.com/customer/products/index.html?action=c2hvd19wcm9kdWN0X292ZXJ2aWV3&pro duct_uid=34825

[justinbowness15]

why do i want that

[AndyT]

err you dont ;D

That was meant for Joebraces

[AndyT]

i now no what one is are any of these suitable http://www.overclockers.co.uk/acatalog/Online_Catalogue_Q_Tec_139.html


Yes Joe, I have the 450w one on that page. Works just fine.

[justinbowness15]

how old are you guys who have doneall the psu's

[AndyT]

umm more than 20, less than 30 ;) ;D.

Seriously it isnt hard. The hardest bit is deciding on how tidy you want it, cause there isnt a lot of room inside the case, and there are a lot of cables. I went for resistors as their neater than the bulb method, but more expensive.

[justinbowness15]

thats what im worried about you see,

im a smart technical minded lad ;D, who studies electronics and knows the basics about electronics but as im only 14/15 and dont want to go wrong and come to a early death :o

[AndyT]

Death? ::) ;D.

2 simple rules to follow to be absolutly sure of living.

1) Unplug when working on it ::)

2) Leave unplugged for 1h (24h if you are really that worried) before you start to allow the capacitors to discharge.

[justinbowness15]

i mean if the wires are wrong or something and i plug it in and bang im a gonna

[KeithA]

Just follow the original instructions at the start of this thread and DON'T open the power supply....

[justinbowness15]

right ive got the confidence do make one now

can someone give me a link of a good quality capible one that one of YOU have got so if i need help you can tell me thanks guys
justin

[AndyT]

Well ok you can do all this without opening the case, but it'll look like **** and all those wires everywhere. Get some proper 4mm sockets, and do it properly if your gonna do it.

Either that or just buy a dedicated 12v psu.

[AndyT]

I see what you mean. This is what you want :

http://www.ebuyer.com/customer/products/index.html?action=c2hvd19wcm9kdWN0X292ZXJ2aWV3&pro duct_uid=34825


Yes, this one ^

[Doomanic]

I've got one of those, it's pretty good, but the 12v rail only produces 11.5-11.8v.
It's ok for charging but a liitle low for powering a 12v soldering iron.

[gatesy]

Mine site constantly at 11.5v.
Mines a bit of a mess, wires everywhere outside the box, so I nicknamed it the Box Of Doom. I cant wait to get a nice little shock off it!! ;D

[DA_cookie_monstA]

If you are not getting the volts on the 12v rail, then you need to increase the load on the 3.3v rail by using a higher wattage bulb, or lower resistance if using resistors.

I can't quite get mine to run two chargers at 6 amps each, but one charger and it is about 12.5v steady.

[justinbowness15]

who has got that one?

so than one will be capable and its good run two chargers of it or just one?

[David Small]

I have the Pro-peak 2500Varipulse adn it say it will charge 0.5A - 3.0A using mains and 0.5A - 5.5A using 12v

Would i be able to use a PSU conversion to run it and get the full range of amps(0.5A- 5.5A)

Thanks

[kevinb456]

yes :D

thats exactly what im doing. just waiting for my damn PSU to arrive >:(

[justinbowness15]

which psu did you buy where from?
pm me

[Moschops]

My 400w PSU handles 2x 5amp chargers with no problems. 8)

[David Small]

If you wanted to it to handle two 7A chargers what size of PSU should you use.

[kevinb456]

well if you judge it by the specifications on the back of the PSU - a 400W should be okay (it outputs more than 14A)

but in reality you should have a margin to be on the safe side. eg if you require 14amps, get one that has 20A+

im not 100% sure but i think a 500W would be the best, 450W may also do, just look at the spec and see how many amps it outputs on the +12v rail.

[Thundercloud]

I can supply brand new 400W PSUs for £21 inc VAT and delivery.

Apologies if I shouldn't say such things here, only trying to help. Own a computer company.

[Mark Christopher]

I can supply brand new 400W PSUs for £21 inc VAT and delivery.

Apologies if I shouldn't say such things here, only trying to help. Own a computer company.


i dont see any rule breaking so i would say your ok!
after all your not selling rc products are you!

[Mark Christopher]

thought you might like this as an alternative to making your own, distributed by Jperkinkinsdistribution so available from most model shops!

http://www.jperkinsdistribution.co.uk/detail.php?JPNO=4460049&activepage=1&Navmain=Batteries/Chargers&subcatname=Chargers

[neveo]

This is a veryinteresting topic and considering the price of 'retail' PSU is a cheap alternative.

Can I take it that NO changes have been made to the instructions on how to build a PSU given on page 1 have been made? If any changes have been made, can they be pointed out now the thread is 16(!) :eek: pages?

TIA

[AL-G]

Hi.
I'm pretty new to RC, i run 1/8th (nitro) & 1/10th (electric) scale monster trucks, i'm wondering exactly what you guys use this PSU for? i worked out you power your battery chargers with it, but what other uses does it have, if any?
I currently only have one AC/DC charger, so don't need a mains PSU for that one, but getting a new charger soon, any recommendations would be appreciated, a twin pack charger would be nice.

TIA for any help / advice.

AL ..

[DA_cookie_monstA]

You can use it for powering a cooling fan, bedding in motors, running a com lathe off, you name it, I even use my soldering iron off of it.

[reubski]

hi have built mine, just needs tyding up i have used a 550 watt psu no messing or worrying that i havent enough power, just wondered where i can get those plugs on the top of your finished product to attach your charger etc. to
thanks

[bender]

I've just got a 400w power supply and am ready to start but I have a few questions. i have read the instructions but I'm still confused :confused:

Where it mentions to keep the thin orange wire with the thick orange wires - All the orange wires on my 20 way plug are all the same size and they're the only orange wires i've got - so do i just keep those together?

With regards to the resistors, do i just put it between one black and red wire from the 4 way plug (for the 5v) and between one black and yellow wire (for the 12v) and then I can use whatever black, red, and yellow wires are left on the 4 way plug for the 12v and 5v supplies?

Finally, my power supply also has a square shaped 4 way plug with 2 black wires and 2 yellow wires only - do these wires serve the same purpose as the yellow and black wires on the "normal" 4 way plug?

[DA_cookie_monstA]

Just follow the instructions ins the best advice I can give you.

If you are getting blinded by the connectors, just cut them off, they are not needed, all RED wires carry the same V, same for the yellow and orange.

[bender]

Well I've got mine all up and running, using resistors instead of the bulb with an additional pc fan to cool them.

I've noticed two things, firstly, the 12v drops under 12v when under a load - so going to a resistor with less resistance should fix that right?

Second, if i plug a mod motor into the 5v line then the power supply just cuts out - it works ok with a stock motor, and even with a stock motor driving the gearbox of a car - but it just seems to turn off when using a mod motor. When you use the 3.3v line then there's no problems, even with a mod motor!

I wouldn't have thought that an unloaded mod motor would be drawing enough current to cause any problems - any thoughts? :confused:

[Bosscat]

Bender,
Changing the resistor will not have the effect you think, it is there as a load to get the power supply to actually work not just to regulate the amount of volts available on the 12 volt rail. The power supply is a switch mode supply and will not even run if there is no load. In any case being a point or two under 12 volts is not a problem, under load most 12v batteries will drop to less than 12 v. My power supply does just that as well!!
With regards to the other problem mine does that as well I dont know why but guess it must be something to do with there being more current available on the 3.3 v line that there is on the 5 v one. I tend to use the 5 v line for the comm lathe and 3.3 for motors.

[webba]

My PSU also drops under load. When i put my charger on it, it says 11.5V, but i can then put my other charger on it and it still says 11.5v. I have had both my chargers running off it at the same time (robitronic and pro-trak) both charging at 5.5 amps and had no problems.

[bender]

Thanks for clearing that up. The 12v line only just drops below 12v - I was just concerned that I'd stuffed something when I built it.

I won't be using the 5v line for anything but a lathe but I just thought it was odd - my power supply's maximum current ratings are (according to the specs on the case): 12v = 18A 3.3v = 40A 5v = 28 A

[~TRAJ~]

i will start on one of these soon but i would like to know if you can just make the power supply to only run a charger off it as i dont need to have 3.3v and 5v.

can this be done? if so what has to be done differently from when making it to include the 3.3v & 5v?

or can i just connect the 12v wires together for - and + without having to use a bulb?

Thanks

[Mark Christopher]

i will start on one of these soon but i would like to know if you can just make the power supply to only run a charger off it as i dont need to have 3.3v and 5v.

can this be done? if so what has to be done differently from when making it to include the 3.3v & 5v?

or can i just connect the 12v wires together for - and + without having to use a bulb?

Thanks
do exactly the same but tape up the 3.3 and 5 volt wires