This is a sensitive, tunable bat detector and ultrasonic sound receiver kit.  It tunes the 18 to 120 kilohertz (kHz) frequency range, using a special ultrasonic microphone, not the usual ceramic transducer with a narrow response centered at 40 kHz.  And since this unit is a heterodyne type detector, you hear the amazing range of bat sounds, not just a series of clicks you get from a frequency divider type receiver.  You will need to solder this kit together, and supply your own "iPod" type headphones and a 9-volt battery. 

The receiver can also be used for hearing other ultrasonic sources in the 18 to 120 kHz range, such as insects, rodents, and electric arcing.  It can hear bats at a distance in excess of 200 feet, depending on the species.

WHAT YOU GET:  All electronic parts and high quality circuit board, with assembly instructions.  To keep costs down, no case is included - the completed project measures 42mm x 60mm x 25mm high. The receiver runs for over 20 hours on a good quality 9 volt alkaline battery. Although stereo headphones are recommended, a small 8 to 32 ohm speaker with a 1/8" (3.5mm) stereo plug could also be connected. 

The miniature surface-mount SEMS microphone (the small gold component near the left side of the board) is pre-soldered to the board for your convenience.  It "listens" through a hole in the circuit board.

The appearance of components in this kit may vary slightly from the pictures.

WHAT YOU NEED: To assemble this kit, you need experience with soldering miniature electronic circuits. All supplied components are through-hole type.  You provide headphones and 9-volt battery, and if desired, a case or enclosure.  The receiver will actually work well on 4.5 to 9 volts, but a 9-volt battery clip is provided for convenience.

Returns - kit may be returned in completely unused condition at the buyer's expense within 30 days of purchase for refund.

Quantity discounts: buy 5, take 10% off.  Buy 20, take 15% off.