DIY Bat Detector
A build your own ultrasonic bat detector kit.
The kit contains the printed circuit board, microphone, loud speaker and control elements. You will need a soldering iron to assemble the kit. The bat detector requires a 9 volt block battery (not included).
The kit frequency range is 20kHz to 100kHz which covers the typical ranges of bats such as Brown Long Eared who are know to have a call frequency 28.1 – 92.5 kHz.