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.
Found in Popular Electronics from the 90s, this circuit generates signals in a frequency range set to...
This circuit provides 6.3V of output from a 9V input. The circuit was found in a Dutch publication from...
Based on operational amplifiers of the time, this circuit from the 1980s has high input impedance. The...