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.
Figure 1 shows a circuit than can be used as time stage in timers, and other applications....
This circuit is from a 1989 Electronics Handbook. The zener diodes are 9 V x 1 W and the...
We can use this amplifier with low impedance headphones with good performance. Possible...