Found in a 1967 Delco documentation, this circuit can deliver power from 40 to 50 W at 8-ohm load. The response ranges from 20 to 20 000 Hz. No information is given about the transformer used.
We found this circuit in a 90's Radio Electronics. The low power circuit activates a 12 V relay...
This circuit was found in a Hands On Electronics from the 80's. The circuit emits an audible alert...
This is a voltmeter with high input resistance. The transistor is germanium. We found it in an...