KUWTP Ep. 12 | 3rd July 2024 | Exploring the world of load cells

Another day, another slay. We decided to work from the comfort of hall today instead of heading down to the MnT lab since we figured we did not need any materials in the lab. Our task for the day was to figure out how to use the load cells and connect them to Arduino (a microcontroller) to obtain results. To our dismay, the load cells we purchased were 4-wire load cells and they are conventionally used singularly instead of as a set of 4, like 3-wire load cells. After scouring the internet for a few hours, we came to a conclusion to simply buy 4 more 3-wire load cells. Let us walk you through our decision making process!

Firstly, it is not impossible to connect the 4 4-wire load cells together, however it would prove to be an arduous task. A 3-wire load cell, also known as a half-bridge load cell, is very versatile and can be used singularly, doubly or as a quadruple. A 4-wire load cells already consists of a Wheatstone Bridge, and is usually used singularly, although we have seen possible circuit diagrams using a pair of 4-wire load cells in a circuit. Since using 4-wire load cells in a multi-cell weighing scale is not common, we decided to purchase 3-wire load cells instead.

Secondly, it would incur more cost for us to use 4 4-wire load cells. A load cell junction box would be required to trim the signals from the 4 load cells, and the box itself is very expensive – prices ranging in the hundreds! Furthermore, more work would be required to figure out how a load cell junction box functions too. However, with 3-wire load cells, we would be able to purchase a combinator and make our lives simpler since a combinator is only compatible with 3-wire load cells.

Lastly, and possibly the most practical reason, is the fact that building weighing scales with 4 3-wire load cells has been done before by others and we would be able to obtain more help in building our first ever weighing scale. Venturing into a less explored area and building a 4 4-wired weighing scale might be too steep a challenge for beginners like us with no experience HAHAHAHA. The image below summarises our internet search history for the day! Enjoy the screenshots from Arduino Forums and other tech websites we read to figure how to build a weighing scale!