Wing Pinger - Test Production & TCR Calculator

Wing Pinger design is finished, test production is started.

PCBs pictured below.
Matt black solder mask, ENIG finish, manufactured in a top-tier factory.

a close up :

There are new functions and interface optimizations on Wing Pinger.
I’ll write about them later.

TCR Calculator

For best temperature stability, I need 3300PPM PTCs. All resistors in Wing Pinger is from KOA Speer, a consistency is preferred, the PTC I could find is LT732ATTD102J3900 at 3900PPM.

According to this paper, I programmed a script to calculate the serial resistor TCR. I did a GUI as eye candy and a python practice. But packing the app was a headache due to OS / package compatibility.

So here is a minimal version that runs from a terminal. It takes resistance / TCR of a PTC and your target TCR, and reply you with the optimized real resistor value in a given E series. Hope it can be helpful.

You’ll need Python3.x and iec60063 package to run it.