Found in a Hands On Electronics from the 90s, this circuit can be easily assembled today, as the FET can be equivalent and the operational is general-purpose.
The TDA2613 is the mono version of the TDA1521A and has pinouts compatible with an integrated...
This circuit from an old 1978 publication uses germanium transistors but can be implemented with...
This project shows how to use an SCR in a starter circuit for a common fluorescent lamp. The SCR...