This simple bridge circuit can be used for impedance or resistance measurement using a high impedance earphone as an indicator. The circuit is from an American 80's documentation.
This circuit was found in a 1974 publication. It provides a tone indication of the temperature sensed by...
This circuit is intended for communications receivers. We can find it in a documentation from the...
This circuit matches a high impedance input signal with a low impedance output. This circuit is...