This modulated transmitter for a light beam communication system was found in the 1991 Electronics Experimenter Handbook. The circuit modulates a LASER diode.
Another of the many tachometer circuits we have on our site. This one is from the September 1976...
This filter for receiving audio in telegraphy was found in a magazine 73 for radio amateurs, in an...
This filter was found in an 80's English publication. However, it can be implemented with modern...