This circuit, which can be found elsewhere on this site, detects positive pulses of a signal. The circuit was suggested in Texas Instruments documentation from the 1980s.
This circuit, which we found in a 1997 documentation, generates powerful signals around 1 MHz. Its...
This circuit was found in an old documentation and can be implemented with BC549 transistors. The...
Found on a 1964 CQ this circuit is intended for tone frequency change modulation (FSK) telegraphic...