I've already done a lot of work prior to creating this project on hackaday so this is just an overview of the past.

So far there have been 3 prototypes. The first was eaten by my dog. It was tested by Fiona for several days. It was discovered that the "SuperCaps" I had selected where more like batteries. They couldn't discharge fast enough to drive the Buzzer and couldn't charge fast enough to be reasonable. This led to my exploration of other options.

The second prototype was designed with a footprint for a rechargeable lithium coin cell. This also proved not to be able to supply the necessary current for the buzzer. Even with a large 100uF+ capacitor to buffer it couldn't keep up.

The third prototype just had an 1206 footprint on the edge to connect a second power board so I could experiment with alternate battery source. I had wanted something super thin and the thinnest LiPo I could find was still about 5mm thick. That is what I used for the 3rd and was the only power storage option that worked.

I wired up the second prototype with the same battery as I was using for the 3rd and put them on Jasper and Fiona for testing. For insulation I sandwiched the boards between 2 layers of Silicon tape. They lasted for about 3 days before problems started occurring. The copper clad film was tearing around the Micro USB connector and cutting off the ground from the power. I expect the professionally produced Flexible PCB's will not have this problem. The batteries had hardly lost any juice over the 3 days and I estimated they would have lasted at least 4 months between charges.

The 4th prototype design which I am waiting on parts for using a different solar charge circuit as well as on board battery protection. I also found some flexible LiPo batterys to use so the whole unit Batter+Solar cell +PCB will be able to conform to the shape of the cat collar. I also opted for the use of much smaller transistor packages as well as a Buzzer 1/4 the size of the previous one. The BLE radio was upgraded to the Long Range version to boost the detectable range of the collar.

By the end of next week I will have the 4th and hopefully final prototype of the electronics board. For packaging I intend to print a flexible rubber case to fit over the components and meld with the battery and solar panel.