need a small power supply

[escin]

i need a small power supply for my peak charger.i need 12v 7amp power supply.it must be small.help me... A.S.A.P (as soon as possible)

 

[Exo]

what is small for you?

7Amps using a normal mains transformer (and required capacitors for smoothing) is not gooing to be really small...

 

[samcheetah]

7 Amps can never be small!!!!!!!!!! that is if u go for a linear PSU

u r gonna need a BIGGG transformer (probably a toroid one), a BIGGG cap, and a BIGGG heatsink. and maybe u would have connect transistors in parallel to get that much current. and all of them will require a BIGGGG surface area to dissipate heat.

so u see it cant be small. but u could go for a switcher. that might reduce the size somewhat.

 

[ante]

Escin,

If you have an old PC power supply lying around, will that be too big and heavy for you?

Ante :roll:

 

[*railmanxaero*]

An old PC power supply is 7 amps? I didn't know that.
Maybe you can modify the PC power supply by taking the circuit board out of the case and custom making your own new case. It wouldn't that small but it might work.

 

[Sebi]

L4970 can do this...

 

[ante]

Most old ATX supply’s have 8 Amps or more and if you don’t use much current from the 5 Volts line you can get a little bit more than the rating from the 12 Volts line. And it is much lighter than a transformer for 12Volts 8Amps.

Ante :roll:

 

[Sebi]

Yes, the PC PSU also a good solution, i've built a 12A 14.4V accu-charger from PC PSU. But the feedback originally on 5V output, so the 12V out not work properly without heavy 5V load.
After rewiring the feedback to 12V out with additional 10k pot. the output adjustable. Also possible the current limiting.

 

[ante]

Sebi,

I have tested different supplies and been as high as 47 Ohms as a load for the 5 V line but I prefer to use a 10 Ohm 10 Watt resistor that have worked fine so far on 4 or 5 supplies. On some of the later models there are a power good signal required also.

Ante :roll: