I've tried all sorts of possibilities to get sound on the computer recordings of birds and Hedgehogs. The bird table camera has sound but cabling it through to the computer picked up more mains hum than bird song.
I had a very cheap wireless microphone which almost worked but the distance was near its limit and the sound wasn't too clean. Luckily I managed to pick up a cheap, unused, UHF wireless microphone working on licence free channels. Setting that up yesterday gave much better results. As usual I modified things a bit. The base receiver is mains powered but the microphone unit uses two AA batteries which is fine for occasional use but no so convenient if it's left on for long periods.
A quick think and a Goole explore session gave me an idea. Cut down two dolly pegs (just the right thickness to replace AA cells), attach wire to contacts screwed to the round head of them and use a 12V gell cell with a bit of electronics to give the 3V needed.
Microphone listening through hole in Summerhouse:
Voltage control: (measured output is 2.99V)
Under £4 on Amazon UK. 4-40V in, adjustable 1.25-37V out up to 2A.
Transmitter set up:
A short recording, Sparrow chirping and Blackbird singing:
A bit of 'noise' but as I have 80 channels to choose from I'll have to do a bit more experimenting. Some background noise was probably local grass mowing.
Dolly peg, a traditional shape of clothes peg (clothes pin) made of wood:
1 hour ago