The big project for today was to take the components above and fashion a completely autonomous solar-powered Meshtastic node and deploy it atop a mast for testing. I started with the solar-powered garden spotlight, above, which can be had in small quantities for about $10 each. I added the Heltec T114 LoRa board, above. It’s a very low power board and I believe it should run consistently from the solar panel and battery in the spotlight even in foul weather.
The T114 is available directly from Heltec for under $20 (it was about $10 when I started this project but has gone up recently) if you get it without the display screen and GPS hardware. Unfortunately, Heltec’s fulfillment partner doesn’t know how to ship to a US PO box nor to a street address that the USPS won’t validate. That’s me and four million or so other households in the US. They were apologetic but I was only buying two radios and they weren’t willing to make the necessary changes to their shipping systeem for my $20 order. If we build these in bulk, I’ll just have them shipped to somebody in town.
Muzi Works came to the rescue, but they don’t sell the boards without the color TFT display which raised the price to $40 for a single unit. They shipped fast and were easy to work with.
I drilled a hole in the beveled edge of the case, which should allow the antenna to be vertical while the solar panel is tilted to the south. I drilled it a little too close to the post for the case screw and had to bend the antenna connector a bit, but that’s easily remedied for future builds (drill the hole a few millimeters more toward the center).
Here I’ve mounted the board inside the spotlight case with mounting putty and mounted the antenna connector in the just-drilled hole.
Next, I soldered the wires for the battery connection directly to the terminals on the battery holder. The T114 actually has its own battery management circuitry, but I proceeded on the (possibly foolish) assumption that the solar spotlight charging circuitry better matched the solar panel to the battery, and I’m bypassing the T114’s charging circuit.
Insert the battery, et voila! the T114 lights up! I’m able to communicate with it via Bluetooth Low Energy.
Next, just for testing purposes, I used Gorilla Tape to affix the assembly to the end of a 10’ length of 1½” PVC pipe. This won’t withstand a hurricane, but it should last a few days for testing.
It’s only been up about an hour. Node discovery takes some time, but we’ll soon see if it works better than the node taped to the side of the house.
—2p
PS. Right now, I’m only using the stubby antenna that came with the Heltec board. Soon, I plan on replacing it with a quarter-wave ground plane antenna similar to the one I’m using for GMRS radios.