Having acquired the tools needed to develop circuit boards, 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. But with a circuit board, I can "flesh out" the circuit. The revised schematic is shown below.

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

• Component positions are available to set gains of both LM386 amplifiers ( C2, C3, R1, R2 )
• Capacitive input coupling is provided for ( C6 )
• Capacitive output coupling is provided for ( C9 )
• Power supply isolation components are added for the first amplifier stage ( C7, R4 )
• Standard LM386 stability components are provided for ( C5, C8, R3, R5 )

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. Part Kits and Assembled Detectors are also 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 have had a number of these boards commercially manufactured. If you would like one for your detector project, drop me an email at: T-Rex@ix.netcom.com