Found in American documentation from the 1980s, this circuit operates in the frequency range 0.5 to 20 MHz. The power can be between 5 and 15 V.
This circuit is from Popular Electronics from October 0, 1981. The diodes can also be 1N4004 and...
This switch or band selector for receivers was found in a Popular Electronics from the 1990s. The...
This circuit, published in 1978, can use any general purpose NPN transistor such as the BC548 and...