Ghostbusters PKE Meter with Espruino

Based on the "Ghostbusters PKE Meter for Arduino" from CountDeM0net on Thingiverse (https://www.thingiverse.com/thing:2338494), I created a version that uses Espruino Pico.
All the details are in the attached (updated) PDF.

2 Attachments

• PKE Meter Espruino.pdf
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Currently the servo does not seem to be strong enough to open the wings fully when the device is closed. When it is opened, the wings can be nearly horizontal. I guess the reason is the bending force needed for the 16 cables coming from the 14 LEDs in the wings.

If you have any idea, how to improve that situation, please let me know.

That looks great - and amazing write-up!

I guess for the LEDs you could try wiring them up in a matrix so that they can be scanned out. For example https://www.espruino.com/Charlieplex should allow you to use 4 IO pins to drive up to 12 LEDs on each side (but if you need to light more than one at once there may be some flicker when Espruino is busy driving the screen).

... or if you can get away with 5mm LEDs (you use 3mm currently?) you could use 5mm individually addressable LEDs like APA106 (https://www.espruino.com/WS2811) so then you only need 3 wires - ground, power and data, and you could set the colour to exactly which RGB value you want.

Also I really like '30 AWG Kynar wire' - Kynar is the type of insulation and it's pretty strong but super thin, and doesn't melt when you try and solder the wire. If your LEDs were wired using that it should put a lot less stress on the motor - even if you're trying to get 8 wires in. Only downside is it's a bit too thin to poke into the protoboard you're using

Hi Gordon,

Thank you again for your answers!

Charlieplexing would have been a solution, however that would mean tearing up the currently glued in LEDs and wires. Also I am not sure, if I want that extra complexity in the code. Adding the display flip already slows down LED walk and buzzer sound intervall noticeably.

Unfortunately 5mm LEDs do not fit into the 3D printed wings and I do not have the skills to change the CAD data. Looking at the WS2811 there probably also would not be enough space in the wings to fit those. Even the 3m LEDs + wires were tight.

So I am probably going to try your third proposal: Thinner wire. Currently I use 0.14mm2 stranded wire with PVC isolation. Likely 0.08mm2 stranded wire with silicon isolation would perform much better. Hopefully I can poke it into the board when I double-fold and solder it.

But as I have now gifted the device to my brothers son, I am not sure when I will have the opportunity to test that. :-)

1 Attachment

I updated the PDF to propose thinner stranded wire for the LEDs.