Ancient Web: Tony Messina Taught the Web to Hear Bats in 1997

Part of the Ancient Web Collection.

Bats fill the nighttime air with calls that human ears cannot detect. In 1997, Tony Messina published instructions for building a little device that would translate some of those ultrasonic signals into audible chirps. The instructions are still on the Web.

Read Tony Messina's Simple Bat Detector project.

Messina describes becoming fascinated with bat echolocation as a schoolboy and returning to the subject after retirement. His goal was not an elaborate laboratory instrument. It was a portable detector that somebody familiar with basic electronics could make from inexpensive parts. He estimated a minimal parts cost of about $25.

The original circuit uses two LM386 amplifiers and a CMOS digital divider. Ultrasound picked up by a transducer is amplified and its frequency divided by sixteen, producing a signal within ordinary hearing range. Messina illustrates the result with an example of a bat calling around 53–91 kHz: divided down, that becomes roughly 3.3–5.7 kHz.

This is a frequency-divider, not a recorder of the bat's natural voice. The conversion loses amplitude information; to a listener the result may resemble clicks from a Geiger counter. Messina explains that distinction instead of promising the equivalent of a professional sonogram.

A paper circuit becomes a worldwide correspondence

The page includes a schematic, component discussion, photographs of handmade prototypes, a parts list, and notes about different enclosures. One builder in Japan used a transparent plastic jar and a film container as a battery holder. Messina built another detector with a decorative bat pin for his wife.

He says he published the circuit in 1997, designed an enhanced circuit board in 1998, and corresponded with people who built versions in countries including India, Poland, Mexico, Japan, and South Africa. These are the designer's reports, not independently counted distribution figures.

The surviving page is explicitly marked first published September 1997; last updated May 24, 2002. It links field reports and even a small WAV file of a recorded bat call, though not every older linked resource was accessible in this review.

What makes it distinctive is that a technical article doubled as a neighborhood workshop spread across continents. Readers could construct a circuit, improvise a housing, send a photograph, and become part of the page.

Explore the detector design and its builder photographs.

Part of the Ancient Web Collection.