This circuit was found in a Popular Electronics from the 90s. The transistors are general purpose, and the gain depends on the ratio between R2 and R1.
This voltmeter has an input resistance of 200 M ohms (47 M ohms resistors can be used in series to...
It is a simple blinker that simulates the action of an alarm when installed on the dashboard of a...
This circuit was found in General Electric documentation from the 1980s. The circuit uses couplers...