This circuit is from old documentation, but it can be implemented with modern transistors such as 2N2222 for bipolar and BF124 for FET. The crystal determines the operating frequency.
We find this microphone voice effect in 1992 documentation. The vibration of the relay contacts...
This circuit for the car uses LDRs as sensors and does not need to be connected to the lamp. The...
Found in a Popular Electronics from the 90s, this circuit can be made with current equivalent...