This lockable two-position servo control system was found in documentation from the 1990s. The error amplifier can be an operational amplifier and the sensors are phototransistors.
This circuit provides a signal of higher frequency the greater the intensity of the light incident on...
This circuit was obtained from a 1978 Practical Wireless. It generates a low frequency, low...
This circuit can be used as a lockable shield. A pulse activates the relay that remains on even...