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…
old wiring… a pain in the ass… a completely mess
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)
- Screen
- Wiring the weight sensor to the HX711 (using some pin header or some pcb screw terminal if you want)
first version pcb shield
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…
the new 1mm end mill to make the holes in the pcb. 3.175mm shank
in this case I used this 1mm drilling bit. 3.175mm (1/8”) shank. And it works perfectly!
First the holes
This time I made FIRST the holes and then the traces.
Then the circuit traces/route
The result was quite good 🙂
this is the second version of the pcb I have designed
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 😀
I have to improve my soldering skills… and improve my tools too
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 😀
the hole circuit is now in a small pcb 😀
Here you can see the cnc job for the PCB 🙂