We found this circuit in an old documentation, but it is still current. General purpose transistors can be used, and the SCR can be the TIC106. The bell is a transducer with an oscillator (buzzer).
This circuit controls a heating element with voltage from 6 to 30 V and current up to 3 A from...
We found this Vox in a 1969 Motorola documentation. Transistors support modern equivalents and the SCR can...
Found in a 90s Elektor, this mixer makes use of integrated circuits of the time. The supply must be...