This circuit provides a reference voltage for calibration. He uses a diode in a small thermal chamber. We found this circuit in an old american documentation.
We found this source with the CI 723, common at the time, in a 1989 paper. Power transistors must be...
Found in an American 80's documentation, this circuit can use common FETs like the BF245 and cover...
This simple passage alarm is powered by the power grid using an LDR as a sensor. The circuit is...