Build an Enhanced Simple Bat Detector
Using a Printed Circuit Board makes it easy !!!

After a little more experimentation, I decided to design a board for an enhanced version of the Simple Bat Detector. I took the opportunity to add components that were left out of the original design for the sake of providing easy prototype style assembly. With a circuit board, the circuit can be enhanced a bit. The revised schematic is shown below.

The circuit is basically the same as the original, with the following additions:

Circuit Designator Component Value Purpose of Component
R1, R2 Varies with transducer used Sets gains of amplifier stages
R3, R5 N/A Amplifier stability components ( not used at this time )
R4 220 ohms Power supply isolation for first amplifier stage
RV1 10K ohms Volume setting potentiometer
C1 .047 uf Signal coupling between amplifier stages
C2, C3 10 uf Amplifier gain control components
C4 470 uf Main power supply filter
C5, C8 N/A Amplifier stability components ( not used at this time )
C6 .022 uf Couples transducer signal to input of first amplifier stage
C7 220 uf First amplifier power supply filter
C9 .022 uf Couples detector output to earphone

Standard component values are shown in the table above. The values of the gain resistors, R1 and R2, will vary according to the transducer used. The board has been designed to allow maximum flexibility in the construction of the Simple Bat Detector. A revised cost estimate for building the detector, using the printed circuit board with a full complement of components, would still be less than $ 35.00. A complete on-line parts list is provided. circuit boards are available !

The printed circuit board layout and wiring diagram is shown above. It is printed as viewed from the top ( component side ). The finished size of the board is about 2" x 1.5" , so it will fit in the same case as used in the first generation Simple Bat Detector. Copyright permission is granted for anyone wanting to use this layout for making a board for their personal, non-commercial use. I try to always keep a small number of these boards on hand. They are available for $6 ppd in the US. If you would like one for your detector project, drop me an email at:

First published December, 1997 - Last update: February 5th, 2011