This circuit is used to detect PLL signals from the 4046 IC. The circuit is from an Electronics Now from October 1994. The indication is made through LEDs.
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...