This high-impedance headphone circuit was found in a 1990s William Sheets. The power is low, but the high input impedance makes it useful for radio applications.
Using a 4017 as a base, this circuit from a 1990s Popular Electronics generates low-frequency...
Approaching the hand or an object to the sensor of this circuit, the relay closes its contacts. The...
This 1967 General Electric circuit makes use of an array of 3 (integrated) transistors for an...