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 synthesizes a sinusoidal signal from logic pulses that can be obtained from an...
With the light falling on the LDR, the relay closes its contacts by activating a warning system. The...
This circuit was found in old English documentation. It can be improved by using resistors of...