Occupancy Sensor, vManyLots

By | 06/12/2020

Work has continued on the occupancy sensor to help with social distancing, I switched from Arduino’s connected using NRF24L01 modules to ESP32s that have a built in Wifi chip.  The former was an unpredictable pain in the backside and the latter just seem to work!

I was due to install these on Saturday but ended up staying home as I wasn’t feeling well (just a cold), and as I’ve a bit more time I’m tidying up.
I’ve decided to use permaproto boards, these are essentially breadboards that you can solder to to make permanent, and they work a treat.  The first attempt worked but the wires were weak and snapped off before I could hotglue them for strain relief.  I managed to move things around on the board and there is just enough room so solder the plugs down.  

One trick I remembered from using strip board at school was that you can drill out spots on the track to separate them.  For the two sonar sensors, the 4pin plugs, they have 5v, gnd, and trigger which are common between them but have an echo pin each.  By splitting between the two sockets I could make better use of the board.

I also redesigned the enclosures, they look much nicer that the cuboid ones I previously had and I threw my logo on there for good measure.  With my Chonky 3d printer the boxes print in 1h20 each so it’s already proving its worth.  

Finally, the last photo.  The chip that popped was a 7805 voltage regulator, the idea is I can run 12v across long wires and though the voltage will drop over that distance there will still be enough potential to get 5v out of it.  Turns out you can’t just whack one of these chips in and hope for the best…

It got very hot, started to brown out, the popped with an almighty bang!  Yeah, I needed new trousers…

I’ve ordered some other regulators that are plug and play which will do the trick and were designed by someone who knows what they’re doing.  Hopefully no more surprises and I can get this installed and done next weekend.

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