Well I’ve made a start on re-building the scales. Things are a bit more mixed than I would like though. Firstly, a bit more dismantling revealed “The Blob”
Not a lot I could do with that, really. Below the LCD was the backlight. Basically, a blue LED baked into some perspex:
So, what am I going to do? Let’s start with the on/off switch. I found a good write up here which provides this circuit:
I only had BC327 and BC337 to play with, not the BC547 and BC557 as shown in the diagram. Guess I need to talk to Kirchoff and Ohm to figure out what values of resistors I should be using. I’ll try that first. It’s not like their laws are complicated, is it?
The display has also progressed:
That’s my one remaining 4 digit, 7 segment display. All working with MAX7219 and Arduino on a breadboard.
Have started transferring that to Adafruit Perma-Proto board, using some ripped apart ribbon cable wire to make the signal connections. It’s going to fit in the case quite nicely.
Obviously, I’ve still got on/off to sort out and there’s the small matter of interpreting the load cell data. Not sure the Arduino ADC is up to it to be honest – it’s 10 bits but the 2 LSB are away with the fairies some of the time. That’ll be 8-bit then. May buy a decent 12-bit i2C ADC for more resolution. Will need to check out the load cell and the INA125P on a breadboard first though.
Still, it’s moving forwards. Nice to have something that is…