This circuit was found in a Hands On Electronics from the 80's. The circuit emits an audible alert when dawn and the sensor receives solar illumination.
Found in documentation from the 1980s, this amplifier uses an integrated circuit from the time....
The purpose of this circuit is to monitor the operation of an alternator in cars with a 12 V...
High selectivity filters can be obtained by combining same frequency crystals in series as shown...