This circuit was found in a 80's Popular Electronics. The sensor can be any phototransistor. The circuit is indicated for an audio link modulated in pulses.
We find this oscillator in a 1980s documentation. The frequency depends on the crystal and the...
ON Semiconductor Phototransistor Output Optocouplers Available from Mouser Electronics is the...
This circuit for controlling high power LEDs (up to 2A) is from a General Electric documentation from...