The Ultrasonic transducer arrangement is working quite nicely. I had to use some rubber pads underneath the transducers to minimize direct coupling when firing the transmitter, but after doing that it seems to be happy.

The next challenge is getting rid of the servo. The original build requires modifying the trap to allow connection of a hobby servo, then the servo is driven by the Trap Box to close the trap. This works reasonably well, but it's got several drawbacks:

- It requires modifying the Trap by cutting the 'pull rod' to be able to connect the servo to it.

- It requires over-voltaging the servo to get enough force to consistently shut the trap (7.2V battery on a 6V servo). I've not had any issues in hundreds of cycles on this servo, but it would be better not to run outside the manufacturer's recommendations.

- Adjusting the connection between the servo and the pull rod is somewhat subjective and it should be more fool-proof.

-Because the pull rod is connected to the servo, it's necessary to disconnect/cut a connection in order to remove the servo (assuming the user wants to remove all electronics before taking the cat off to the vet, this is a hassle for the user and unnecessary extra stress for the animal).

What I plan to do here is use a solenoid to actuate the trap. This is a good option since the solenoid is cheaper and simpler than the servo. The problem is that I've not had much luck sourcing a 6V solenoid that has enough force to consistently close the trap. I have a 12V solenoid that works great, but as of now the system works on a 7.2V battery, and when we start looking at 12V batteries the price starts jumping up fast! I'm currently working on a simple boost converter to step my 7.2V up to 12V+ for long enough to hit the solenoid.