Found in a European magazine from the 1980s, this circuit can amplify signals from 10 kHz up to over 220 MHz with good gain. MOSFET supports equivalents.
This FM advertising suppressor (SCA) decoder circuit was suggested by Signetics in a 1980s...
We found this circuit in an old General Electric documentation. In fact, PUTs are not common...
We find this simple musical instrument in a 1977 Radio Shack documentation. The key resistors must be...