3 ms·

Awesome work! If I had known that the maker of this is here himself, I would have refrained from submitting something that could have been a great "Show HN"! My

Awesome work! If I had known that the maker of this is here himself, I would have refrained from submitting something that could have been a great "Show HN"! My apologies. I'm not too knowledgable about electronics, so maybe this idea will sound dumb: could one replace the strain gauges with serpentine traces on top and bottom of the suspensions and use these for the same purpose? It might be difficult to route other connections into the central part of the PCB then though. Edit: I just saw that there are two strain gauges, not four as I initially assumed. Edit2: maybe even single-sided strain gauges could work when placing one each over the connections of the suspension with the central, circular part and the outer frame? These places should bend in opposite directions when pressing the button, shouldn't they? That would leave one side of the PCB for routing connections over the suspension. Edit3: in the end, it would be another feature to support, so creating one's own gauge sensors might be anything but a good idea.

scottbez1 5y ago
I'm not super familiar with strain gauges, but I've seen some discussions about designing them as part of a PCB and it seems like 2 concerns come up: resistivity and, to a lesser extent, trace width. It sounds like strain gauges may use a metal with higher resistivity than copper, which means you get a higher overall resistance (the ones I'm using are 350 ohm) which is better for stable measurements. With copper traces, and especially if you're using the cheap PCB manufacturing services with large minimum trace widths, I think you'd end up with maybe single-digit ohms, which would use more power and generate more heat (which would then also change the resistance). But if it could be made to work it would be amazing and simplify the design a lot! So I'll have to keep an eye out in case anyone does more experimentation in that space.

scottbez1 5y ago

I'm not super familiar with strain gauges, but I've seen some discussions about designing them as part of a PCB and it seems like 2 concerns come up: resistivity and, to a lesser extent, trace width. It sounds like strain gauges may use a metal with higher resistivity than copper, which means you get a higher overall resistance (the ones I'm using are 350 ohm) which is better for stable measurements. With copper traces, and especially if you're using the cheap PCB manufacturing services with large minimum trace widths, I think you'd end up with maybe single-digit ohms, which would use more power and generate more heat (which would then also change the resistance). But if it could be made to work it would be amazing and simplify the design a lot! So I'll have to keep an eye out in case anyone does more experimentation in that space.