One of my old job was a BilancIno. A weight scale made with Arduino. My parents need a junck-cheap weight scale. We have already bought a couple of really china weight scale… but the board of the weight scale keep to blow up…
So I replace the old dead board with an arduino.
The circuit was made with a bread board… it works… but it was a pain in the ass…
You can see it in the next photo…
So I decided to made one with a pcb using my cnc 😀
I use a HX711 as interface between the arduino and the weight scale sensor. I’m going to use the PCB (the shiled) to wire and interface all the following things
- Button: it will used to set the tare and for the autocalibration of the weight scale
- Buzzer: it will used to give audio output to the user (turn on, tare, autocalibration)
- Wiring the weight sensor to the HX711 (using some pin header or some pcb screw terminal if you want)
The first prototype didn’t work ’cause I used the same V bit to drill the holes, and that made the copper too thin to a proper solder…
in this case I used this 1mm drilling bit. 3.175mm (1/8”) shank. And it works perfectly!
This time I made FIRST the holes and then the traces.
The result was quite good 🙂
But I made a mistack… I have inverted the Vcc and GND pin for the HX711 (and I killed one of these chip 😐 ). But I didn’t want to trow away another pcb… so I bent the pin of another HX711 and give it power trought external wiring. Not so elegant… but works really FINE 😀
The circuit is now very small, more manageable. And the quality of the signale form the weight sensor to the HX711 is way better than before. I have now a 1gr precision 😀
Here you can see the cnc job for the PCB 🙂