/diy/ - Do It Yourself

>>2393088
Yes. Just make sure you use a current limiting resistor suitable to the voltage, and don't short anything. If you know what you're doing you could use zener/LED thresholds to get different LEDs on at different voltages, which could be neat.

>>2393113
>>2393116
Just so you know, the circuit you've ended up with is designed as a single-supply circuit (audio connector's ground is the lowest voltage).

I'd personally design it to be split-supply (audio connector's ground is halfway between). This basically means connecting the audio input grounds to the node between R6/R7 (Vref), and doing away with all the high-pass caps (C1, C2, maybe more) as doing so will reduce or even eliminate startup pop (assuming you mirror C4 up to the 9V rail). This also usually means redefining the "ground rail" triangular symbol to be that middle rail, running the ICs off ±4.5V.
It's less conventional with guitar circuits, but I prefer it. The one downside (I think) is that it means you can't use the audio jack's switch to disable power.

Also consider adding node labels to your digram, Vref, V+ and V- are ones I often use, helps get rid of long connecting wires. Wish the guys making the Silicon Chip magazine would catch on, picrel. Works just like how connecting them with the ground symbols does.

>>2393122
Buffering Vref basically means you can use far smaller caps on it, especially if the current going in/out Vref is high. Maybe 10nF or whatever, with a battery supply you can maybe even ditch the caps entirely. For a low-current circuit like this it probably doesn't matter., but if you have an extra op-amp from a quad/dual IC I'd do it anyway.

>>2393237
How do you want to mount the force sensor, ideally? Most of the time a few strain gauges on a load cell is the best method, but it really depends on your geometry. Pressure-sensor-based may be a bit too sensitive to changes in ambient pressure, though I guess a small vent hole would act like a high-pass filter.