Bought a 20-0-20 200VA transformer from Farnell (not a toroid). Bought it for a power amp (amp5 from 41Hz) which I am building. I have tested the transformer for its output voltage and for checking the amp's power supply. Today the transformer started humming when I turned it on. Is it...

I got this schematic off the net for a adaptor for old flashes to be used on digicams. (Schematic in attachment) I need clarification on two points: 1. What is ZD1, is it a zener diode? 2. The schematic of the triac has only one lead labelled "G", does it mean it doesn't matter which of...

I have built several CMOYs and 2 Pimetas. Never had problems with DC offset. I have also built a few amps using Sijosae's design of the 74HCU04 chip without problems. However the latest one I built has DC offset of 30-50mv on one channel, the other channel is perfect. The amp has an input...

Just built this amp using two stacked 74HCU04 chips following Sijosae's schematic, using stripboard. Sound's not bad, very similar to the CMOY with BB OPA2134. A little too dark for my taste but I liked the idea of it running off two AA batteries in an Altoid tin. Seems the batteries last a...