I thought I would post the latest incarnation of my bat detector. I never actually found out how my first one fared after giving it to a friend but I've left this one with the people at Hessilhead Wildlife Rescue so it should hopefully get some good testing through the week.
I added a gain control to the preamp to give a bit of control over background noise and feedback. The high pass filter doesn't do very much. I had calculated the component values for 5kHz but the high gain and slow rolloff probably negate any filtering.
The rail splitter will also be alot simple in future designs (I'll include some of those ICs in my next component order)