12vDC to 12vAC


2007-12-15 6:46 pm
Hey guys,

I built and amp recently that runs off of 12vAC.

I want to use this amp in my car (12vDC). The amp draws a max 30-40Watts. I doubt using a bridge rectifier would be enough -> too much current.

How could I go about cheaply and effectively doing this? :smash:

Cxrazy said:
What else would you need to know?

Well there are a few possibilities here that rely on knowing how your amp functions.

Amplifiers run on DC, not AC, so what does the other part of the power supply on the amp look like? Is it a voltage doubler, or does it just make a single DC supply?

Going from DC -> AC -> DC in a car would be pointless if your amp just runs on a low voltage single supply. In that case you could just power it straight from the cars DC.


2007-12-15 6:46 pm

This small amplifier is constructed around the TDA1521 IC, capable of delivering 2x15W RMS
(4 ohm) or 2x10W RMS (8 ohm). The IC is thermally and short circuit protected. THD: .07% (1W/1 kHz). Frequency response: 7 to 60,000Hz (-3dB). Requires 2x12 VAC, 2A transformer (sold separately). Net weight: 1 lb.

Thats what it looks like. maybe it uses those diodes to rectify AC to DC.

This amplifier can be run with a DC-DC converter. You will occasionally see the Vicor high power/high voltage converters on EBay, but the price is typically more than just buying a Class-D amplifier brick for auto uses from parts express. You can use the amplifier single ended as well -- just capacitatively couple the speaker output leads. NXP shows how to do this on their website. Leave the caps in, take out the diodes.

I think that about 10% of the members of this forum are old enough to remember vibrator power supplies used in tube radios for cars -- they were pretty darned noisy. An NE555 or SG3524 will do roughly the same thing.