An Interesting find at Banggood – HX711 Strain Gauge Signal Conditioner Module

In a past life, I used strain gauges in a number of applications – measuring weight with a load cell, cable tension with a load cell or stain-gauged clevis pin, torsion in propeller shafts and other apps. All of these applications required expensive instrumentation that was sometimes difficult to set up and use.

I came across this HX711 module that's a complete strain gauge signal conditioner and excitation source for five bucks. Add an ESP32 and you have a wireless strain gauge system for the cost of lunch. Kind of unbelievable.

Sparkfun has an HX711 breakout board for just a little more, but it uses headers for connections that are probably inadequate for use with strain gauges (measurements depend on small deltas in resistance). The Banggood module has a 4-pin Grove connector for the microcontroller interface and a 4-pin plugable terminal block for the strain gauge bridge. I've started including 4-pin Grove connectors in my designs, as they have become somewhat of a standard for a number of Chinese suppliers, including Seeed Studios and Elcrow's Crowtail system.

One detail – the interface of the HX711 is not I2C but more like SPI with a clock and serial data.

Christmas 2018, my daughter bought me a house plant. As any plant I've every owned is no longer with us I decided I needed to keep this one alive. I ended up with a HX711, a DHT22 and an ESP8266 (wemos) board. Combined with a 12V water pump it formed an automated watering system. It also logged the conditions, this is the chart it produced.
The cost of all electronic components has dropped tremendously and has made projects like this cheap and easy. I don't think they had that particular model back then and I used this one. It was a very good learning experience - managed to get my head around HTML, CSS Javascript etc.

Mike.

Wow. The module you used is $4.50, including the load cell beam. Unbelievable. Binocular-type load cells used to cost a fortune.