This circuit is from a documentation about the MC1723, Motorola equivalent of the well-known 723. The transistor admits equivalent and must be mounted in a good heat sink.
In the figure we have a simple amplifier stage for BC547 series transistors. The gain is...
Found in a 1980s American documentation, this circuit can use a SCR and a general-purpose transistor....
This circuit was found in a 1973 publication. The operational ones can be exchanged for...