This circuit is from the 1989 special edition of Radio Electronics Experimenter. The circuit was created with SMD components to be mounted on a keychain.
This circuit generates a pulse of approximately 1 second when the light incident on the sensor...
The 3403 operational amplifier is not common today, but the configuration can be implemented with...
This circuit, published in 1978, can use any general purpose NPN transistor such as the BC548 and...