ATM your using the +12V and -12V rail, the combined differnece between the two should give you 24V, not 12V. the +5V and -5V should add together to give you 10V.

Its a little hard to explain why, but you should be using only the +12V and the ground. Think of the ground as 0V. +12V is 12 away from 0V, as is -12. +5V is 5 away from 0V, as is -5V. Its a bit like different AC phases, 415V is achived by the potential difference between 3 different waveforms (3 phase power).

It seems that your getting a fair bit of voltage drop there, too much for the triton, hence the reason you require the resistors on the +5V rail.
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Jeff Ferrara
fb@ffej.net

ffej.net

Hey all,
I am after a power supply still but for a gws charger (much less stress and current than a triton). Just phoned the donkeys at jaycar and the cheap repaired goods ones cant be brought in and such and i was wondering what other people thought.
I still have a copmputer supply to tear out of one of nicks computers still.

Also i tested the other power suipply (computer based) that nick gave me and it jumped around a bit then and the highest it reached was 9.8 and such. IS this normal (i was also checking teh correct plugs and wire i think).

I just need something for about 50 bucks as power supply or else i will have to buy a big SLA (18 amper) and use that.

Please help.
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Andrew Welch, Team Unconventional Robotics

What does the GWS charger pull, about 5A or so?
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Jeff Ferrara
fb@ffej.net

ffej.net

DO NOT USE THE -ve voltage rails
they are intended for small current applications only
max rating on those rails is 1A MAX.
as they basically arent used i wouldnt try pulling any more than 500ma from them and would try to keep it under 100ma

wrt PC power supplies in general
my current $35 ATX psu supplies 15A on its 12V rail alledgedly
this is small however
if you hunt around computer markets you should be able to find a 20A or possibly 25A 400W supply for around $40 or so.
antech is a good brand of powersupply but quite expensive.
roughly speaking you can judge the quality of a psu by its weight.
compare a antech 400W with a 400W cheapie
then compare the cheapy with the one labled 300W you will notice a similarity ;->

oooookay questions time.

i was just having a look back over this thread to see if i could figure out why my atx psu wont give out the full current, and i think i now why. is it because:

an atx psu needs a dummy load on the 3.3v AND 5v rails? im using two 1ohm 10w resitors in series on the 5v rail but what should i be using on the 3.3v one?

and what is the reccommended way (if there is such a thing) to get rid of all the useless wires hanging out of the psu? can i just cut them off on the circuit board itself (obviously after its sat for a while for the caps to discharge.)
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www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz

yeah most of them are just soldered into big areas with heaps of holes, so they can be chopped or de soldered.

Most modern PSUs don't need a load on the 3.3 or 5v rails, but some might need that.
I have used some older AT supplies with no problems like that.
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The Engine Whisperer - fixer of things

your load isnt *drawing* the current
if the voltage is staying constant at 12V or so then the load is the problem.

equation
V = IR
voltage = current * resistance

you can create a voltage
current flow is a result of that voltage.
your GWS charger rember we hooked it up to like 16V and it still wasnt pulling much in the way of current.
_________________
Mechanical engineers build weapons, civil engineers build targets

quote:

---

Originally posted by andrew:
I have had a change of heart with nicad charger. i am now leaning towards the 75 dollar gws charger as it should charge all nicad and/or nimph packs in future and is a great price.

---

yeah ive got the omni, quite nice. the only thing that it doesnt have over the gws charger is that it draws so much current.

i hooked it up today to my car charger and it started to charge the 12v pack straight away, the voltage was like 13-14v out of it and it was charging at .5A from a 2.5A charger.

so that figures that this thing needs at least 12amps and a voltage thats alway s above 12v.. my psu at the moment isnt staying above 11.7v at the moment, but with a few 10w wirewounds it should work.
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www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz

I use to run that Omni of a 4amp car charger Glen. The best way that I have told you is to just connect it to a car battery. NO F'king problems then!
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https://www.halfdonethings.com/

okay i hacked the psu with a 10 ohm 10w resistor as that was all i could find...

seemed to help as the voltage went from 11.35 without it to 11.8v, but this still aint enough to make the charger charge a 12v battery. so im going to slave two psus together to see if i can get them to give both the voltage and current.

if your reading this andrew (dumhed) do you think you could measure the output voltage of the psu you use to power your omni charger? thanks if so.
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www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz

you could always get a power suply made up ready from RMP lol mine arived the other day
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as a shadow is seen and not heard i am here
-Waddy the phoenix

if you pay for it gladly lol
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www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz

*limited time only (1 day only from now) order 5 tritons and chargers and pay 50% into my account and i will pay the rest*

hows that for an offer and thats per person not per group
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as a shadow is seen and not heard i am here
-Waddy the phoenix

sounds good to me wayde
keeping in mind i know where you live ;->
_________________
Mechanical engineers build weapons, civil engineers build targets