I was the other day fixing a phone (land), and saw the rubber pad with all the numbers and buttons, and for the first time, after having seen these rubber pads in my portable consoles, TV remotes and basically everywhere, I asked myself...
Wait a second, how in heavens these rubber (RUBBER!!!) switches work?
How can they close the circuit?
So I checked continuity with my DMM and BOOM, no continuity, no BEEP, no threshold trespassed. That automatically means, wow, these SWITCHES either don't work or are pretty much broken. However these things still worked, flawlessly, but how, I was thinking.
So I measured resistance and I was getting so very bad values, between 5000 ohm and 300 ohm, depending how much I pressured them. Every time I've seen a switch it's designed to, well, be a switch, no resistance at all.
So my question is... How these work with such high values for a switch?
Yeah, I've read there's a thin layer of carbon at the bottom black rubber part, but still, why so much resistance and how do they work in all the appliances so well, having 300 ohm?
How do you check if these are worn or not then?
Starting with their value, which is quite varying.
Even more importantly, why a switch with such high resistance was ever designed or accepted?
Wait a second, how in heavens these rubber (RUBBER!!!) switches work?
How can they close the circuit?
So I checked continuity with my DMM and BOOM, no continuity, no BEEP, no threshold trespassed. That automatically means, wow, these SWITCHES either don't work or are pretty much broken. However these things still worked, flawlessly, but how, I was thinking.
So I measured resistance and I was getting so very bad values, between 5000 ohm and 300 ohm, depending how much I pressured them. Every time I've seen a switch it's designed to, well, be a switch, no resistance at all.
So my question is... How these work with such high values for a switch?
Yeah, I've read there's a thin layer of carbon at the bottom black rubber part, but still, why so much resistance and how do they work in all the appliances so well, having 300 ohm?
How do you check if these are worn or not then?
Starting with their value, which is quite varying.
Even more importantly, why a switch with such high resistance was ever designed or accepted?