This circuit was found in a 1971s English magazine. We can still assemble it using BC548 transistor. The other components are common. The supply voltage of 6 or 12 V depends only on the relay.
This circuit was found in old Maxim documentation. Check the availability of the IC if you are...
Found in documentation from the 1980s, this amplifier uses an integrated circuit from the time....
This circuit was found in the 1972 RCA Power Transistor Databook. Transistors can be replaced by...