This circuit is from an 80's publication. It makes use of small 6 V x 50 mA incandescent lamps. The diodes can be general purpose or even 1N4002. The transformer is 6.3 V with 100 mA or more current.
The use of a detector bridge instead of a single diode, as is normally done in common galena...
Found in an English documentation from 1989, this circuit is intended for equalization of cassette...
This circuit can be used in alarms, data links or áudio links using IR radiation. The circuit is...