Mr Evil's Realm
ESTD

Amp4 - Subwoofer - Power Supply 1

Posted:
Output voltage: ±20V
Output current: 0.2A

The circuit is taken straight out of the datasheet. I made it variable so that it can be reused in future projects if needed (regulated power supplies are always useful for something). It could supply more current if a higher voltage transformer were used, at the expense of increased power dissipation. With the 15-0-15V one I've used, the input voltage drops too low for the regulator to maintain a 20V output at around 200mA; more than sufficient for the amp, which requires only 20mA or so.

Schematic

Schematic

I have included protection diodes around the ICs, just in case of accidents. The LEDs provide a quick visual indication that the reservoir capacitors are charged and that the fuses (not shown in the schematic - they're between the reservoir capacitors and the LEDs) are not blown.

PCB layout

PCB layout

Rectifiers and reservoir capacitors are included on the PCB to keep things compact. Ground from the reservoir caps/transformer is kept separate from everything else on the PCB, being connected at the main star-ground, which is a copper strip bolted to the case. There is also a local star-ground on the PCB. LEDs are mounted under the fuse holders, which just happened to have convenient screw holes there!

Building and testing

Here's a photo of the thing assembled:

Photo

Not much to say about it. These ICs are very reliable and easy to use, so it all just works.