This is a circuit for receiving signals from the previous transmitter. The circuit uses a common phototransistor. It was found in the August 1984 issue of Radio Electronics magazine.
Frequencies up to just over 100 kHz can be obtained with an oscillator based on one of the four...
This circuit, found in a Popular Electronics from 1992, is based on an oscillator and a crystal...
This is a discrete equivalent version of an open collector TTL gate. What we have is an inverter...