Found in the August 1993 Electronics Now magazine, this circuit employs two symmetrical source 741 op-amps. The output is fed to a true RMS measurement circuit.
This old oscillator using germanium transistors has a high impedance headphone as inductor to...
This old fashioned amplifier can source some watts to a low impedance loudspeaker. The circuit...
This 50 Hz rejector or notch filter was found in a 1975 documentation. Other frequencies can be...