This circuit reverses the signal if both positive and negative. We found it in an American documentation from 1969.
This circuit was found in a 1977 Radio Shack documentation. The circuit is tuned to 1.4 kHz, but...
The transistors of this timing circuit may be more modern types such as BC548 and BC558. The...
This circuit is from a 1980's documentation for telecommunications. The circuit is used in SSB and...