This circuit is from a 1980's documentation for telecommunications. The circuit is used in SSB and the diodes must be suitable types for the application. The audio input is low impedance.
In the figure we show how to use an LM324 as a voltage comparator the reference voltage is...
We found this circuit in a 1964 Electronic Design. It provides 0.5 V signals from 4 kHz...
This circuit is from a 1992 documentation, but the components used can still be easily assembled. The...