This circuit was found in an American 1980s documentation. It analyzes the exhaust gas of a vehicle using a special sensor. The indicator is a milliamperimeter.
The Texas Instruments TPS7A92 integrated circuit consists of a low-voltage (LDO) linear voltage...
This circuit to increase the sensitivity of instruments to 100 uA (or close to it) was found in...
This voltage controlled oscillator uses a varicap to change the frequency. Usin a 100 turns coil...