OK, for those who have been waiting for the bat detector schematics for the #FSCHACK bat detector, here's a sketch.
Here's what it looked like on a breadboard at the hack day.
And here's the prototype that I knocked up in my workshop near Okehampton and found its way to Slapton via MozSpace London.
So what about the component values you ask? Well I could post them here, I might yet, but over the weekend I've been experimenting with another design which I believe will be cheaper, more sensitive and easier to use.
What is really exciting for me about the new design is that it replaces most of the electronics with maths. I like maths! Even better if the maths isn't right, or could perhaps be better, it can be changed and no soldering is required and no unwanted components are discarded - or more likely added to the junk box.
Part of my inspiration for this change was this diagram.
The diagram comes from a datasheet for a 3mm x 3mm integrated circuit sold to mobile phone makers to add FM radio receive, and transmit, capability to their phone. That's very clever, and ridiculously tiny, but for those of us familiar with radio circuits, this is clearly not an FM radio. So what is it? Well it's a device for converting analogue signals to digital and digital to analogue with a DSP (Digital Signal Processor) in between.
So the plan now is to create something very similar for listening to bats.