A quick update on the status of the Sol BLE Tracker. I'm just repeating whats in the video above in text down here so if you watched it there is nothing new below.

I'm currently working on producing the 4th prototype of the tracker, due to the smaller packages I used to save space I've been having some trouble with the soldering. I got everything on alright but while trying to rework a resistor when it somehow shorted to another trace underneath where I couldn't see I tore off a trace that went under a DFN transistor 1mm x 0.6mm and that made the battery protection section basicly a lost cause. I'm planning on changing that section to a LTC4071. Its a combined LiPo battery protection circuit as well as charger. It has lower quiescent current and requires less external components. No transistors in particular. Its also an MSOP-8 which will be much easier to solder than the 2 DFN transistors and the DFN charger package as well as taking up less overall space. The only downside is its only rated for 60mA current which the buzzer should draw more than. I think I can get around this with some decoupling capacitors near the buzzer. In the current design however both the charger and battery protection where tested to be working.

I continued to assemble the board despite this SNAFU when I discovered I did not order the 4.42M ohm 0402 resistors. These are part of the solar charge circuit. I'm going to try and get some 4.7M ohm 0805 resistors in there place to test with. I want to measure the current to or from the battery in various lighting conditions to make sure the charger is working as expected.

You can see in the picture below one of the NPN DFN transistors I used for the buzzer. I'm going to swap these out with SOT-923F package transistors which have leads. This way if something goes wrong I don't have to scrap the section they are in because of it and it will be much easier to solder them. They are bout the same size as the DFNs anyway. I changed to a smaller buzzer in this design it takes up about a quarter of the space the old one did. Another thing to note is all the jumper resistors. They are only in this design for ease of construction. The production PCBs will be made by FlexPCB. I'm going to use a second layer for the jumpers and use the bottom layer as a ground plane as well which should also help RF performance.

Expect an update about the current measurements to the battery from the solar charger in the next few days.