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.

ZeroLiPo: Pi push-button battery power control

The ZeroLiPo is a Lithium-ion Polymer battery power manager for the Raspberry Pi from Pimoroni.

It does not handle battery charging, it simply converts the LiPo 3.7Volts to 5Volts, and provides a low voltage alarm.

Although I've had one of these for ages, I've only just considered using it, possibly for my Bat Call Logger.

Bat Call Logger: Wolfson audio card frequency response

Having got my Wolfson Audio card working happily with a Raspberry Pi 2, I decided to try and check the frequency response.

As this card is described as a 'audio card' and the only figures I've seen relate to the audible range, I didn't have high expectations regarding its use in my Bat Call Logger.

Anyway, to find the answer, it was just a question of setting up some test gear and running a few checks.

Bat Call Logger: recording ultrasound

My bat project has been on the back-burner for the last few months, as I understand that bats don't venture out much during the winter.

However, the Weather Man on BBC's Winterwatch did say he had seen them flying around on a few mild evenings during January!

So maybe its time to do a bit more work on my Bat Call Logger and check if there are any out there.