A small loudspeaker (2.5 or 5 cm) can be used as a low impedance microphone. A preamplifier and impedance matcher must be added and this is shown by the figure. The circuit can be powered from one or two AA or AAA cells. Current drain is very low.
A small loudspeaker (2.5 or 5 cm) can be used as a low impedance microphone. A preamplifier and impedance matcher must be added and this is shown by the figure. The circuit can be powered from one or two AA or AAA cells. Current drain is very low.
