The transistors of this circuit found in a 1965 magazine can be the BC558 and the sensitive 12 V x 50 mA relay. The other components are common.
This circuit was originally designed with the operational 747 which is rare today. However, the...
This circuit was found in a 1975 technical publication. The circuit can be designed with 741...
The TDA2613 is the mono version of the TDA1521A and has pinouts compatible with an integrated...