What did you build today (Pictures) ?

[NeverDie]

Made a dead-bug op-amp circuit to help measure open-circuit voltages created by nano-amp currents generated by a solar cell illuminated by just 1 lux of very dim light:

This picture is actually just the LDO part of the op-amp circuit, where I was able to solder the prescribed surface mount capacitors directly between its pins. The larger circuit is described on this thread: https://forum.mysensors.org/topic/10812/the-harvester-ultimate-power-supply-for-the-raybeacon-dk/122
Why dead-bug you ask? Since the circuit depends on the correct measurement of the effects of mere nanoamps, I didn't want any leakage currents that might happen on a protoboard, which can be significant when it's just a small number of nanoamps and their effects that's under scrutiny.

[sundberg84]

Updated my GW with the code @mfalkvidd provided to monitor OK and NACK

[nagelc]

I got tired of twisting DuPont cabels to get from different programmers to different boards.
This is an adapter that lets me connect the programmers I commonly use (Jlink-mini, BMP, STLink clone) with the boards I commonly program with straight through wires. I left a couple unpopulated for future in and out.

[tbowmo]

Finally I am starting to do a little electronics again.. First thing is a prototype assembly of RASLE (Rpi Arcade Sound and Light Extension). It's a custom made arduino "coprocessor" for a raspberry pi, built into retropie arcade cabinets. It's a joint project with a couple of friends that are building arcade cabinets (I built mine a couple of years ago, I think that there is pictures earlier in this thread).

Features:

• stereo 3W class-d amplifier
• atmega328p
  • 3 pwm channels for LED strips
  • a port for WS2812 type led strips
  • pwm channel for fan
  • output for a relay to control mains input for the box (let the rpi shutdown cleanly, before disconnecting power)
  • 5 button inputs (shared between rpi and atmega)

[franz-unix]

Hi, finished two nodes based on the same multi-purpose battery powered pcb (all the documentation here)

One is a door / window sensor based on a Reed switch.

If someone is interested, the dedicated wiki page contains the detailed build instructions.

The other is a soil moisture sensor.

For this one, the wiki page is here.

Happy Easter, even if at home!

[NeverDie]

Anyone know or have experience with how well the underlying capacitive soil moisture sensors hold up over the long term? Clearly they're better than the cheap conductive electrode kind, which for most people don't last very long at all, but I recollect reading that water ultimately invades the PCB enough on even the capacitive designs that it goes kaput. Maybe they've been improved since then or maybe there are now known tricks for how to fortify them against that happening?

[franz-unix]

@NeverDie Good question. My is too young (2 days) to say something.

Here a possible solution. See at about 9:50

[BearWithBeard]

@NeverDie The guy with the swiss accent once said that you can coat the capacitive soil moisture sensors with a water resistant varnish or put it inside a waterproof shell.

https://www.youtube.com/watch?v=udmJyncDvw0
starting at ~7 mins.

@franz-unix Ha, Great minds think alike. :D

[franz-unix]

@BearWithBeard :+1: :grin: I love the video of the swiss guy!

[Yveaux]

@BearWithBeard ah, now I know who 'the guy with the Swiss accent' is :)

[sundberg84]

Today I have a very strange problem. I have created a new outdoor sensor which is powered by a 240v-5v HLK module. Its working VERY intermittent and should send data every 5 minutes (no exceptions).

Whats even more strange is that, when my outside node (called multi) is working, I have a battery powered node (sleep 15 min - send - sleep) that seems to go down, and the other way around (not always, but quite frequent - could be very unrelated but I have notised it a couple of times now).

Anyhow, Im very glad i build my logger node - works great once more. I use this so often and really recommend all with a bigger network to have some sort of mobile debugger. Most of the times I use the bluetooth module (2xAA powered) but at this point I have my node on my workbench powered by a USB adapter (orange wires). I then parasite power from the node to run the debugger and is now logging everything to a sd-card.

[mfalkvidd]

In case anyone hasn't seen the logger before, it is available at https://www.openhardware.io/view/532/The-Logger-Machine-Short-and-long-term-serial-logging

[sundberg84]

Another picture from today:

Just started working with coincells - CR2032 to be exact. Anyone knows why the battery % varies with the given temperature? Are those coincells very temp. dependent or I have made a misstake somewhere... ???

[Nca78]

@sundberg84 said in What did you build today (Pictures) ?:

Anyone knows why the battery % varies with the given temperature

They don't like it when it's too cold. Check page 4 :
https://data.energizer.com/pdfs/lithiumcoin_appman.pdf

[Yveaux]

@sundberg84 looks like you can ditch the temperarure sensor and just use the battery voltage to measure the temperature :muscle:

[cloolalang]

433 MHz ESP 32 MQTT Gateway with proper antenna

[sundberg84]

@Nca78 - Well, its been around 14-17dgr C today, so almost room temp. Strange
@Yveaux - hahaha, best answer! Saving uA!

[idanronen]

@NeverDie sorry if it's a bit off topic, but I see that 10 pin ARM box connector you use in several of your designs, and I was wondering if it offers anything extra in addition to the regular 6 pin programming pins. I'm asking specifically because I want to try some of your nrf52832 designs, but would like to avoid spending extra money on special connectors and cables. Thanks!

[NeverDie]

@idanronen No, nothing extra. It just conveniently and transparently interfaces to the ribbon adapter cable used by the Nordic nrf52 dev kits for programming external nRF52 MCU's. If you want to roll-your-own, you can do away with most of the pins. I myself migrated to a smaller connector in later designs.

[idanronen]

@NeverDie thanks for clarifying!
So for example in the mini breakout board (https://www.openhardware.io/view/471/Ebyte-nRF52832-Small-Breakout-Board) I could just align the 6 pads and use a standard 6 pin pogo programmer right?