This simple circuit for the 3 to 30 MHz range was found in the Electronics Experimenter Handbook Special Projects of 1983. The coils consist of 10 and 50 turns of 32 wire on a 1 M x ½ W resistor.
For times in the range of seconds to a few minutes we found this timer with the CK722 in a Radio...
We can use this amplifier with low impedance headphones with good performance. Possible...
Found in a 1964 Electronic Design, this circuit uses transistors from that time. Equivalent...