Inside a Microswitch

We’ve taken a few microswitches apart, mostly to fix those pesky Logitech mice that develop double-click syndrome, but we’ve never made a video. Luckily, [Julian] did, and it is worth watching if you want to understand the internal mechanism of these components.

[Julian] talks about the way the contacts make and break. He also discusses the mechanical hysteresis inherent in the system because of the metal moving contact having spring-like qualities

We always have trouble holding the little plunger in place, so we liked [Julian’s] idea of holding it in with a spot of putty. If you want to know the reason he was playing with the switches to begin with, look at the second video. His 8-bit breadboard computer uses a switch like this to drive the single-step clock.

We did a detailed look at microswitches a not long ago, so if you want to dig into more details, that’s a good place to start. As for breadboard computers, we like them too.

15 thoughts on “Inside a Microswitch

  1. In the usual words of Crocodile Dundee, “You call that a micro-switch? /This/ is a microswitch.” If you have ever fiddled with the tiny, tiny power and volume switches inside a mobile phone, you know they put the micro in microswitch. My old eyes can barely resolve the tiny contact pins.

    1. Isn’t “Microswitch” a brand name? I had some forty years go, actually still have the keyboard with some of the switches remaining.

      They were somewhat small, but the part to be pressed was very small, and not requiring much pressure. The mouse switches are even smaller, so I assume “micro” came before they realized they’d need smaller switches.

      Michael

  2. To fix the “double-click syndrome” on my mice, i just take the mouse apart, spray some isopropyl alcohol into the switches, push them a few times, and blow out the IPA with compressed air. So far, i’ve managed to save a few mice like that without taking the switch itself apart or solder in new switches.

    1. I’ve done few transplants, when mouse button becomes unresponsive or need to be pressed really hard I find other mouse in parts bin and swap the switch, luckily it seems all mice use the same microswitches.

      1. I don’t like taking the whole mouse apart because I never get them back together quite right at the base and they “feel” different. So I pull the top, pop the switch off in place and replace the little leaf spring. It is frustrating getting the switch back together in that position, but it is possible.

  3. the bane of my existance, fortunately i had a large number of old 90s ps2 mice in my junk pile. an endless supply of cat toys (they like the ball) and replacement key switches. bout a year ago i scrapped all the keyswitches and stuck them in a bin, and chucked all the mouse skeletons. a mere year later and im down to my last 4.

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