We found this circuit in an English publication from the 60's. The transistors are of germanium of the time and the headphones must be high impedance magnetic.
This circuit allows you to read resistors up to 20 M ohms, converting it into voltage. The circuit is...
The circuit in the figure is a useful continuity test serving to check the condition of circuits and...
This circuit beeps when the sensor is triggered by the opening of the freezer door or other...