Using a common crystal diode and a 741, this circuit can be used to detect microwaves. The circuit is from old documentation and the switch selects the gains.
A small loudspeaker (2.5 or 5 cm) can be used as a low impedance microphone. A preamplifier and...
The circuit of the figure can provide voltages of 5, 8.9 and 12.5 V at its output, all doing this...
This circuit, from a 2002 documentation, checks the logic levels of the inputs, providing a...