This circuit was found in an Elektor from the 90s. The circuit uses common components even today, requiring a symmetrical power supply.
This circuit is from a Poptronics, American magazine from August 2000. The circuit can be...
This circuit was found in an 80's Radio Electronics. The circuit makes use of general purpose...
We found this circuit in the 1960 Mullard transistor reference manual. The phototransistor can be a...