Using an LDR as a sensor and an operational amplifier this circuit was found in the Encyclopedia of Electronic Circuits volume 5 from 1995. The circuit triggers an optodiac.
This circuit was found in a 90s Radio Electronics. It is intended to amplify the sound channel of...
A bridge with greater sensitivity and, therefore, lower consumption for the microcontroller...
Found in a 1964 magazine, this is a small headphone amplifier from 500 ohms to 10 k ohms (magnetic...