This ultra-simple adjustable power source is of great use on the bench of any electronics practitioner. To find out what voltage is being delivered to the load circuit, you can connect, in parallel with the source output, a common multimeter in the appropriate continuous voltage scale or use a 0-15 V movable iron voltmeter. The adjustment of the output voltage is made in the 1k potentiometer P1. The filter capacitor C1 should be as large as possible, so that no snoring is introduced in the eventual supply of audio devices. Transistor Q1, type 2N3055, must be mounted on a heatsink. The maximum current that can be obtained from this source is linked to both the capacity of the transistor and the transformer. For common applications, transformers of up to 2 A of current can be used, with the maximum current available in the load of the same order.
