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.
The circuit shown in the figure has elements for maximum gain at maximum speed. By setting the...
This instrument, based on a 555, measures frequencies up to 1 kHz, but its scale can be modified by...
Using a CA3130 operational amplifier, this circuit was found in an English publication from 1977....