Found in a 1968 Motorola documentation, this circuit operates at 1 kHz and can deliver 20 V from 12 V. Transistors support modern equivalents.
This traditional configuration is from a 1976 publication, showing that nothing has changed since...
This circuit is temperature stabilized. Modern equivalent transistors can be used, and the power...
This circuit was found in a 90s Popular Electronics. The sensors can be common speakers that reach...