This circuit with the HA2400 was found in the March 1980 Radio Electronics magazine. The circuit has digital-gain control and must be powered by a symmetrical 15 V source.
Found in old documentation, this circuit makes use of amplifiers of the time, uncommon today. Next...
This sensitive electrostatic charge detector uses only common discrete components. The circuit can be...
We found this circuit in a 1979 Poptronics. The circuit can be easily assembled with the use of...