This 4-tube counter was found in Radio Electronics magazine from December 1959. The circuit uses a coil as a sensor to detect the passage of metallic parts or magnets.
This circuit changes the dynamic range of an audio signal. The integrated circuit used in this...
This circuit uses PNP transistors that can be BC558, but if the power is reversed, BC548 can be...
We found this circuit in old documentation from National Semiconductor. The circuit makes use of a...