This IR light sensor circuit was found in the July 1992 issue of Radio Electronics magazine. It is tuned for 20 kHz modulated light.
This circuit allows you to read resistors up to 20 M ohms, converting it into voltage. The circuit is...
A small loudspeaker (2.5 or 5 cm) can be used as a low impedance microphone. A preamplifier and...
This inverter was found in an old European documentation, but components are still current. Only...