We found this circuit in an old RCA publication. The components are of the time, admitting equivalents. The circuit is triggered in two ways using LDRs.
This circuit provides a reference voltage for calibration. He uses a diode in a small thermal...
This circuit for model making was found in an English documentation. The SCR can be the TIC106, and...
The operational amplifier used in this circuit is no longer very common, but the configuration can be adapted...