This circuit can modulate a laser rate at frequencies of 50 kHz. We found the old documentation. The bipolar transistors can be the BD135 and 136 and the FET admits equivalent.
This circuit matches a source of high or medium impedance audio signals with a low impedance...
Found in a 1993 Electronics Hobbyst Handbook, this circuit uses components that are still common...
This pulse width-tuned circuit was found in the March 1996 issue of Electronics Now magazine. The...