This simple circuit to monitor the frequency of the power grid uses an analog indicator. The adjustment trimpot can be 4k7 and the indicator is 100 mA full scale.
This small automotive NiCad battery charger uses only passive components and has the number of...
This circuit was found in a 1987 edition of the United States' Hands On Electronics magazine. The...
This 20 Hz high-pass filter was obtained in a 1965 American publication. The operational amplifier must...