• Working on an update

    Steve Smith12/06/2023 at 23:48 0 comments

    Have been using my propane weight scale hack for over a year and it is awesome!  Life caught up to me and I didn't get to finish my hack logs, but I will have more time now to make more entries about the software in the last few weeks of December....so stay tuned.!  In the mean time...here's a shot of one of the iPhone screens that I designed using RemoteXY application....it's amazing...!

  • HX711 wiring and the TinyPico ESP32

    Steve Smith06/03/2022 at 18:06 0 comments

    Now that I had the Wheatstone thought out, I connected it to the HX711 and wired it as per the example schematic.  I had to add the two fixed 1000 ohm resistors per the diagram to make the Wheatstone a full four cell bridge.   I added in the color codes of the load cells to the sketch and it is wired internal just like this really Ugly hand sketch shows.  Having found the HX711, I went looking for an ESP32 type chipset that was the smallest unit that I could find that was in stock and available.  I stumbled into the TinyPico.....it is a full ESP32 with WiFi and BLE and extremely small.  I will take more pictures of the installation in future log entries.  But I was able to wire it up and tested it and it worked with the example sketches...!!   A lot of software work needed to be done....and I was still on the lookout for a way to communicate with an iPhone.   The hunt for that continued......

    The TinyPico ESP32 Super Small Chipset

  • Drawing out the Wheatstone Bridge with Resistors. Amplifier selection.

    Steve Smith06/03/2022 at 16:46 0 comments

    Having drawn out the main PCB portion....I measured the load cells and did another Ugly Sketch of just the Strain Gauges and how they configured into a wheatstone bridge.   Knowing this would allow me to add my own load cell amplifier to this circuit and then output to an AVR type microprocessor.   Since I didn't need to recreate the wheel here....I ended up using the HX711, which already had libraries that were well documented and were usable in ESP32 type chips.....which I wanted to use because of their WiFI and Bluetooth capabilities.  Wiring diagrams are on the SparkFun page....but I will do a full diagram when I am done with the project.

    Sparkfun HX711 Load Cell Amplifier

  • Decipher and Sketch PCB Strain Gauge Connections

    Steve Smith06/03/2022 at 16:11 0 comments

    I started off this project by trying to understand how the existing scale platform was electronically connected.   So I just started drawing a sketch based on iphone pictures that I took of the PCB and load cell wiring.  It was an UGLY view into basically a 3 way Strain gauge wired as a WheatStone bridge of sorts.  The big ah-ha moment was that there were few 3 strain gauge load cell wiring diagrams on the internet......but after deciphering their PCB, I noticed that they filled in the fourth strain gauge with just passive resistors that were trimmed to equal the series resistance of the other 3 strain gauges.  So I had a VERY UGLY but preliminary sketch and that was a good start!