This light meter circuit was found in 80's Radio Electronics. The circuit uses a milliammeter as an indicator and the sensor is a common LDR. The power supply must be symmetrical.
We found this circuit in a publication for radio amateurs in 1974. The bipolar transistors can be...
Found in a 1980s American documentation, this circuit has a current consumption of only 1 mA. The...
This adjustable power supply was found in Ferranti's transistor manual from 1974. Power...