Tesla/Voltcraft BK127C Power Supply: a trusty fellow

One of the first pieces of electronic equipment I have ever owned, maybe the very first, a 0-20 V power supply, 1 A max. current. Made for Voltcraft (brand of the “Conrad” electronic mail-order company, popular in Germany), by Tesla, “Czechoslovakia”.

In the mean time, I have 3 of these, and despite the “1 Amp” limit, these are very useful supplies, and there are hardly any circuits that need more than 1 Amp. The output is reasonably low-noise – very similar to other DC supplies or power packs.


Build quality is very sturdy, folded steel – and a basic but very reliable circuit, designed around a uA723.

bk127c schematic

Years ago, I had one of the supplies fail on me, when powering a high voltage circuit – this caused the power transistor, a KD606, to fail. Replaced it with a BD317 – working perfectly fine.

The manual – sorry, in German only.
tesla bk127c pwr supply

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