Electret Microphone Preamplifier

This design runs from a 5Volt USB supply and attempts to minimise electrical noise.

I wanted to create a simple preamp for an electret mic insert using components from my bits box.

So component values and transistor types are not critical.

Bat Call Logger: more on call analysis

Following my last post I have had some time to analyse a few more bat recordings and consider how to streamline my work flow.

Until recently, I've been carrying out all file operations using Audacity.

But there are a few things I can do via the command line, which I've pulled together in a Gambas GUI program.

Bat Call Logger: the hardware

My bat call logger combines a frequency division bat detector with a Pi based audio recorder.

Recordings are simply triggered by a short stream of pulses from the detector (i.e. "activity").

Having spent a bit of time trying to optimise the hardware, I now need to document what I've done, before I forget why I've done it!

Bat Detector: electret microphones

Building your own Bat Detector is a relatively easy electronics construction project.

The tricky bit can be locating a suitable transducer or microphone that has a useful frequency response into the ultrasonic range used by common bats.

During the last few weeks I have been testing a number of devices, and here are my notes.

Bat Detector Overhaul

About 8 or 9 winters ago, I made a bat detector based upon a circuit published by Chris Eve.

It has never quite lived up to expectations, and has been modified a few times over the years without great effect.

But now its time has come, and I'm looking more closely at ways to improve performance.