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Black Widow Audio

Power Supplies

Power Supplies - By Dan Ward.

External Power Supply Unit

Figure 1


It may seem trivial but a decent power supply for any circuit makes all the difference. The best thing is that most people are capable of designing there own basic power supply, however simple, you may want it or need it.

I am hoping to learn from this article if you want to call it that, although I have been doing lectronics for years, I have things to learn, quite alot really! Aswell as myself, this should help to answer a few questions...

An Example?

In figure 1. You can see a power supply I build originally for my Headphone Amp, and while I was designing it I decided to make it more useful, added a few extra voltage outputs, presto. It did cost me a fair bit to build but that is because I have got a big toroidal Transformer and nice case for it. On the back I used 4mm Banana plugs to make it flexible and I make up leads as I need them. See Figure 2.

Power Supply Connector Leads

Figure 2

These leads are quite heavy duty, aircraft rated cable, rated at about 10amps, the most each one of my outputs can supply is 1amp! so there is plenty of leaway...

This supply works excellently, I have never heard any noise, and have attached it to a scope and it looks clean. As far as I could comment on the sound! I cannot hear it affecting the sound it allows the amps and units I run from it plent of power and a rock steady voltage. Due to loads of decoupling caps and large transformer.

Basic Formulae

There are a few essential formulas you need to build a Power supply.

Were V is Voltage, I is Current and R is Resistance
Were P is Power (Watts), I is Current and V is Voltage
Vp = Vrms*1.414
WereVp is Peak Voltage and Vrms is Root Mean Square Voltage



Transformer, Bridge Rectifier & Capacitors



Voltage Regulators





National Semiconductors Website, Voltage Regulator Datasheets

ESP, Elliot Sound Products



Page Updated

06 October 2001

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