We found this balanced modulator circuit for DSB and possibly SSB transmissions in US 1980s telecommunications documentation. The diodes can be replaced with equivalents.
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...