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 is a small FM transmitter, capable of carrying its signals over short distances...
This circuit is intended for underwater communications. Of course, the critical point is the...
Originally this circuit excites an incandescent lamp, but it also serves for LEDs, if they use a...