Hacking Your Mouse To Fix The Misclick Of Doom

The Best Case Scenario And The Aged Scenario

All of this discussion about the non-ideal mechanical and electrical properties of switches is nice, but what does it actually translate to in practice? Here is what the signals from a fresh C&K ZMA00A switch look like with a 10kΩ pull-down resistor connected to both the Normally Open (NO) and Normally Closed (NC) contacts while the common contact is connected to 5V supply:

The oscilloscope is triggering on the first rising edge on the NO side to capture the moment the blade touches the NO contact and provide a repeatable timing reference for everything else surrounding the main event. The two signals are offset vertically by one division for improved readability. As the switch's plunger gets depressed, contact on the NC signal breaks cleanly most of the time (or not so cleanly in this case, since I deliberately picked a dirty break waveform to make sure I did not mislead some people into thinking that breaks are clean). Between the moment when the blade fully clears the NC contact and touches the NO contact, there is roughly one millisecond of travel time where the blade touches neither and both outputs are low. After that, the blade bounces for about 500µs on the NO contact before settling.

How repeatable is that switching performance? I turned infinite persistence on and triggered the switch about fifty times to see what sort of trends would emerge.

There is a spread of about 700µs between the quickest and slowest NC contact breaks, a minimum travel time of 840µs regardless of how quickly or hard I pressed the switch and the better part of 800µs of bouncing before the NO contact's signal becomes clean. You may also notice that the first three bounces on NO contact closure are highly repeatable. The black area between peaks indicates that each switch closure produces bounces that have nearly identical timing relative to the trigger, which is surprisingly regular considering that I was trying to be as irregular as I could in actuating the switch to get the most variance possible. When the switch's blade crosses the tipping point, whatever force was initially applied to the plunger to get there appears to have negligible further effect on the switch's own internal forces and the blade settles in the NO position within 700µs of bouncing. There did not appear to be a clear correlation between how quickly I pressed the switch and how quickly the switch went from break to make, except for the few times where I was deliberately pressing slowly and could hold the switch between breaking and the tipping point for arbitrarily long, which is where the NC signal entering the screen capture low (already open) comes from.

That's the performance of a nearly new switch, a few months old from the factory and maybe two thousand clicks into its life.

The Aged Scenario

What do those switching characteristics look like after many years of aging and likely over a million clicks? Based on what I said earlier about mechanical tolerances getting sloppier from wear, fatigue, oxidation and contamination, and electrical performance doing much of the same, you should expect the switch to get slower mechanically and noisier electrically.

Where will I find some well-worn switches for comparison's sake?

Nearly 20 years ago, when optical tracking was still new, I received a Logitech TrackMan Marble as a birthday present. Back then, these used to retail for around $100. I loved it until its left mouse button exhausted my patience. Not figuring out how to fix it and throwing it onto a shelf may have been a blessing in disguise, as I doubt my cramped thumb would have survived many more months of use.

Time to hook up that left button and see how well it fares in comparison.

In this single-click event, we see 800µs between the first sign of break on the NC contact and the signal going to a steady low, 4.2ms until the NO contact initially goes high, another 1.2 milliseconds for the bounces to settle and then a signal that never fully settles at the supply voltage due to dirty or oxidized contacts. That's 6.2ms total switching time for a representative sample on the worn switch versus 2.2ms worst-to-worst spread for the new switch. That's all the evidence I need to say that if I wanted a quick and easy fix, I should simply put in new switches and call it a day.

Let's accumulate waveforms through fifty actuations and see how much variance there is in the old switch's behavior.

I knew the old switch was bad, but I was not expecting it to be this horrible. The NC contact can take over 10ms to break, the travel time can exceed five milliseconds, and the NO contact still hasn't fully settled even 12ms after initial make. The old switch has a performance spread more than an order of magnitude worse than the new switch.

While not as steady as the new switch's, the old switch's first two to three bounces are still far more repeatable than I expected. The first two are clearly identifiable on the waveform. With the worst bounces still shorter than a millisecond, it should be easy to filter them out through various means.

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  • Rheotome
    I'll never look at a Mouse the same way after reading this !!!
  • SirGCal
    My problem with my MS is just finding a mouse I can use well period.I have some mice like this trackball myself and still can't use it properly. I need one controlled with the mind instead of hand. Which is probably coming sooner then we think.
  • mrface
    This is a really cool article. Thanks for sharing.
  • theaudiophile
    Holy shit, you're crazy in many many ways. I am an electronics hobbyist myself, and you sir are simply insane. I hope this article gets enough traffic and ad clicks to make up for the time you put in instead of replacing switches.
  • mikesinner
    Both me and a friend of mine have already bought new mice, but I did keep the old one, a logitech G700 with the terribly annoying double click glitch when only single clicking. It's not a very old mouse either, so I find it very disturbing that the switch is already worn!
  • Daniel Sauvageau
    2213136 said:
    Holy shit, you're crazy in many many ways. I am an electronics hobbyist myself, and you sir are simply insane.

    You give me too much credit. This is a simple hack once you know what you are dealing with - finding out what you have to work with is usually the most tedious part of a modification job, especially when you don't have design schematics or someone else's instructions to start from.

    The hack might be more trouble than it is worth but it does show that there is no reason for mouse buttons with SPDT switches to glitch until the switch mechanically fails. Other than mice manufacturers choosing to design them this that way that is.

    399868 said:
    Both me and a friend of mine have already bought new mice, but I did keep the old one, a logitech G700 with the terribly annoying double click glitch when only single clicking. It's not a very old mouse either, so I find it very disturbing that the switch is already worn!

    My G500S is about four years old and the glitching is at that early stage where I'm not sure if the glitches are caused by the mouse or by mouse movement when I click.
  • razor512
    Wouldn't it be easier to just use hall effect switches (like with some industrial machines)?

    The switches can be magnetically shielded, and as long as the button actuation functions (no broken springs), the button will continue to work, along with any vibrations of the actuation being calibrated out in software.
  • buzzrattie
    Wish there were a mouse that was cat-hair proof. Dang little buggers shedding all the time, and getting into the laser.
  • Daniel Sauvageau
    129458 said:
    Wouldn't it be easier to just use hall effect switches (like with some industrial machines)? The switches can be magnetically shielded, and as long as the button actuation functions (no broken springs), the button will continue to work, along with any vibrations of the actuation being calibrated out in software.

    I doubt switches that require additional calibration steps would be popular in a market where manufacturers are trying to optimize every penny of profit they think they can get away with out of their product.

    One option which does not require calibration is optical sensing: poke a slotted stem through the detector. Most mechanical mice used optical wheel encoders to convert ball motion to digital. The same thing could be done for switches.

    I doubt either option would be as inexpensive as a mechanical switch and with the "memory" version of my hack, it would be a practically free fix. Free is a tough price to beat.
  • waltsmith
    I agree totally that the reason manufacturers don't already implement one of these fixes or possible even a better one is simply, as you said, that it would screw with their replacement cycle. This kind of "designed to fail shortly after the warranty expires" philosophy is an integral part of the modern "consumer economy". I'd warrant that purposeful design flaws such as this are present in almost every modern "mature" consumer product branch.
  • 80-watt Hamster
    I was more excited than was probably appropriate when I saw they mouse you were modding. Been using a Trackman Marble+ (same thing with a wheel) since '98. I don't make my living at a computer, and don't use the Trackman much for games, so it probably hasn't had as hard a life as yours did. In any case, it's still going strong, and it's nice to see that repair is a viable option if it ever goes south. Great article, even if most of the electrical stuff went in one ear and out the other.
  • Nuckles_56
    When I read the title, I was wondering if April Fools day had come early... But thank you for what turned out to be an excellent article
  • spentshells
    Quote:
    My problem with my MS is just finding a mouse I can use well period.I have some mice like this trackball myself and still can't use it properly. I need one controlled with the mind instead of hand. Which is probably coming sooner then we think.


    I'll take one of those please.
  • Tom1945
    Mice last for years and they're cheap. When they fail I simply buy another rather than waste my time fixing it.
  • Xivilain
    This article, is why I like Tom's Hardware. Keep up the good work!
  • video99
    I don't suppose we will move on from mechanical switches in this application since it provides the short stroke and click feedback all in one. An optical or Hall Effect switch would still need a mechanical click function, and that would still wear out.

    It would be nice to hear back from the likes of Logitech or Microsoft about why they appear not to have implemented a proper de-bounce circuit of this type and when they intend to do so!
  • alidan
    if the mouse was guaranteed for life, and the laser was user replaceable with no hassle, id be willing to drop 400$ on the mouse. it would need a 12 pad on the thumb though.

    im so sick of mice wearing out, you finally found the perfect mouse, then 4-5 years later it dies, and you are on the hunt again because that model is no longer in production, and quality took a nose dive while you were away.
  • Shankovich
    These kinds of articles are what brought me to Tom's in the first place. Love it!
  • Spanky Deluxe
    Fantastic article, this kind of stuff is what originally brought me to Toms Hardware about two decades ago and I'm so glad to see such in depth technical detail again. I don't think I've ever seen a clearer example of planned obsolescence in action. Next time my mouse dies, I'll be sure to replace the switches; I hate adjusting to a new mouse!
  • NeatOman
    LOVED THIS ! !... I just had to take apart my Logitech Performance MX Laser mouse I've had for far too long now to add tension to the springboard Omron uses on there switches. Two years ago i did the left click and i just did the right click, also released some tension from the scroll wheel to add a longer scroll when i flick it.

    The mouse is now about 7 years old and still great :/ WTF other than some noticeable input lag.. wont let it die.. I'm the one relative that wont pull the plug. FYI i use a wired mouse for gaming.
  • Calvin Huang
    Quote:
    I agree totally that the reason manufacturers don't already implement one of these fixes or possible even a better one is simply, as you said, that it would screw with their replacement cycle. This kind of "designed to fail shortly after the warranty expires" philosophy is an integral part of the modern "consumer economy". I'd warrant that purposeful design flaws such as this are present in almost every modern "mature" consumer product branch.


    It's unlikely that this would happen in most industries, it's just not worth the effort in most cases. It's hard enough to design and manufacture a reliable, durable bug-free product as it is. It's just not worth the trouble/risk to introduce precise failures into the product. Market research might tell you the average usage patterns, allowing you to calibrate a component to fail, on average, a few weeks after the warranty period. But if you miscalculate, then you're looking at lots of products failing before the warranty period expires. Also, there's no guarantee that people will replace a broken mouse with another from the same company. If this were common practice, it would be very easy for a manufacturer to buck the trend and, without increasing their price or costs, produce a product that is far more reliable than any others on the market. Such a company would then enjoy the higher frequency of mice replacement built into their competitors' products as well as being viewed as higher quality than competing brands.
  • Uniblab
    Im on the other side of the posting. I have a "Microsoft Wheel Mouse Optical" that has been in use for 14 years. I sometimes connect two mice to my computer at the same time so when I want a mouse that has a few more features all I have to do is set this one aside and use the other. Try it, it should work for anyone since all I did was connect the two to the same computer. Both were microsoft though. The point is that this is one of the best mice ever made and how microsoft designed a great mouse. It totally shows the wear of being used, I should give it a spray cleaning - fantastic, Mr clean or whatever, but it fine where it counts. It simply works. Even the red led that is on its rear is as bright as it was when I first got it. Microsoft should reissue it as a classic so we can get new ones. A really good design.
  • Larry Litmanen
    This is a fascinating article.