Found in Philips' 90s documentation, this small source can use modern transistors like the BD135 for TR4 and the BC series for the rest.
This circuit is from the American magazine that no longer exists Science & Electronics,...
This circuit is based on the voltage drop of the diodes in conduction, in the order of 1.6 to 1.7...
In a September 1992 Radio Electronics article, we found this basic 555 circuit used to generate fixed...