Old consumer tech is supposedly obsolete but can also be incredibly rewarding to open up and explore – you might find some intriguing, or even head-scratching engineering decisions inside. KuzyaTech tore down this 1970s-era calculator and found a little bit of both:
Notice the color of the wires and the polarity indicated:
And here’s the calculator’s VFD display shot from the side:
Read more & see pages from the operator’s instruction manual here.