PC Power Supply Modification

[makuang]

usually, the reference of PWM circuit in a PC PS attach on +5V. since most of RC Charger need 12V or higher, you have two ways to do:
A: simple way:

1. enable the PS. if it is a old AT PS, no need to enable, just power up. if it is a ATX, short pin 14(power on, green color) to ground. just short 14-15 or 13-14, because 13 and 15 are commom ground.

2. add a dummy load on +5V, you and use a 6V 15W light bulb ar even a high power resistor to make sure there is about 2A on +5V. calculate the value of resistor:
V=5v, I=2A, R=V/I= 5/2=2.5 ohm.
V=5v, I=2A, P=VI= 5X2=10W.
so we need a 2.5-3 ohm, 15W resistor as a dummy load. try to touch the resistor to metal casing. it will be hot while the PS is working.
with this dummy load, the problem of vlotage drop while a heavy load applied will be insignificant.

3. wire up the PS, connect 12V output to charger, install a switch and a LED...remember you need a current limiting resistor to connect series with LED, otherwise the LED will just burn out when you switch on. around 330ohm will do, depends on how light the LED you want.

[makuang]

B: Best Way:

No Voltage drop at all, you can adjust output voltage to any value around 12V, say 10V or 13.8V~~~~~~~~

will write it after lunch~~

[makuang]

up load some pics first~~

Chargers

[makuang]

Charging some Huge lipo batteries. these are special assemblied pack for client which requires high current during charging from my power supply. the PC PS can take it with out any problem, even power up my VHF ham radio in the same time.

[makuang]

Yes,, here he is

[makuang]

so many wires... heavy load~~

[jason_ices]

last nite i heard the device crying heavy load.

[Mad Armour]

Re: PC Power Supply Modification

Originally posted by makuang

2. add a dummy load on +5V, you and use a 6V 15W light bulb

Went to buy an ATX today but couldn't find the bulb. Guy at SLT says that 6V 15W is available as halogen bulbs rather than tungsten. Where did you buy yours or is there an alternative?

Thanks.

Mike.

[9VDXN]

question...why do you need to have a dummy load on the 5v output?? How does it affect the 12v output on the powersupply ???

[9VDXN]

question2...how much 'ripple' is the DC current from the PSU since you're using it to power your ham radio too? Is your transmission clean when you call for a signal strength check?

[Mad Armour]

Ok....I can only get a halogen bulb 6V 20W. Can it be used as the dummy load at the +5V? The other available bulb is 6V 10W.

Thanks!

[proman_11]

nice fireproof ventalated area to charge your batterys

[Mad Armour]

Yup....that was quite scary.

[genexis]

Got continuation ??

Originally posted by makuang
B: Best Way:

No Voltage drop at all, you can adjust output voltage to any value around 12V, say 10V or 13.8V~~~~~~~~

will write it after lunch~~

[genexis]

Re: PC Power Supply Modification

Originally posted by makuang
2. add a dummy load on +5V, you and use a 6V 15W light bulb ar even a high power resistor to make sure there is about 2A on +5V. calculate the value of resistor:
V=5v, I=2A, R=V/I= 5/2=2.5 ohm.
V=5v, I=2A, P=VI= 5X2=10W.
so we need a 2.5-3 ohm, 15W resistor as a dummy load. try to touch the resistor to metal casing. it will be hot while the PS is working.
with this dummy load, the problem of vlotage drop while a heavy load applied will be insignificant.

How will this affect the 12 V supply ?