Help for power supply !


first I want you to excuse me my english because i'm french and I speak a very very bad english.

So, I want to realize himself my amp for my car, i've found schematic.

it's an amp which give 360Wrms in 4Ohms

but i have to made a power supply for it :

symetric +/- 70V so approximately 15-20 A

I don't know how I have to do for made this power supply

I hope that one of you have an idea

Thanks jeremy.

PS : if you want more explication or if you not understand something, ask me.


2005-08-16 6:47 am
Your amp puts out 90w x 4 RMS?

I don't think European car audio equipment takes different voltages from US stuff the way home electronics do. Your numbers are very confusing.

An amp of that power should be wired to the battery across a 100 amp fuse, or maybe less. I think it's about 25 amps per 100w of amplifier output.

The car charging system puts out 12v constant. The 70 number must be something else.

Do you have a link to the spec sheet for this amp?



Try this: (360W / 4W)^ (1/2) = (90) ^ (1/2) = 9.486 Amps
Now this: 9.486A x 4W = 37.94V

So, to get 360W into 4W, you will need a good, stiff supply rated at +/-40V at +/- 10A, or a power supply that peaks out at 800W!

This may be easy to design, can be done, but don't expect this to be small, or easy to construct.

Best voltage-mode PWM IC chips to use are the TL494 (uncommitted outputs) or the SG3525AN (totem-pole outputs).
Best current-mode PWM ICs are the hi-speed MC33025, or the UC1846 (both with totem-pole outputs).

These chips are sold by a variety of manufacturers and have good website documentation.

Hope this helps,