This bench circuit was found in Radio Electronics magazine from June 1958. The circuit does not have an external power supply. The circuit generates signals from 12 Hz to 180 kHz in 4 bands.
This 1/2 hertz high selectivity filter was found in the December 1990 issue of Radio Electronics...
Currents of a few milliamps are enough to drive loads up to 500 mA with this circuit. The...
This circuit is from European 90s documentation. The integrated circuit used is not very common...