marten repellant

since my car and chickens are a subject of marten attacks i wanted to build this device. it repels the martens with a sound that is not to be heard by human ears, but is a pain in the b.... for martens.it is , in fact a short burst of aproximately 23 to28 khz, and its repeating, so the marten does not get used to it. It started with the condition that it had to be usable both in the chicken house aswell as in the car.This ment a powersupply from 9 to 12 Volt. since it also needed to be a simple construction, an adjustable frequency range and low power consumption, it was evident that we needed a microcontroller to do the job. We ended up using an Attiny25-20 with a few components on the side, but loaded with smart software, and a strong piëzo tweeter, to get the right sound to drive away martens and /or other creatures that are nibbling on carcables or chickens. It is a very simple design and all of the components are through hole type. The pcb that we made, is very small and can be tucked away in a very small place in the car or housing. potentiometer P1 controls the frequency off the reppeller and gives you the opportunity to adjust this to reppelling different animals. this project is easy to build and a good starters project, and we are considering making a kit of components for it.