Results 1 to 9 of 9

Thread: Tactile switch conundrum

  1. #1
    Anodized. Again. Konrad's Avatar
    Join Date
    Aug 2010
    Location
    Canada
    Posts
    1,060

    Default Tactile switch conundrum

    Mobo has a variety of onboard tactile switches which do cool and useful things.

    I'd like to be able to do these cool and useful things without having to open a side panel and reach under piles of crowdy components, preferably with some buttons mounted right on the front of the chassis.

    These tactile switches are soldered onto the mobo PCB.

    I don't want to do any soldering or electrical mods to the mobo itself - I plan to swap mobos from time to time and the chassis needs to be interchangeable, so semi-permanent soldering isn't a practical option anyhow.



    The only idea I can think of is to use bicycle brake cables, I push the easy-to-reach button on one end and the metal ferrule (or whatever) on the other end pushes against the hard-to-reach tactile switch button.

    I suppose I'd need to fashion little plastic brackets to securely clamp over the tactile switch casings.

    I don't know a lot about bicycle parts. It looks like 5mm OD is the smallest commonly available, smaller is better for this application and I doubt I need thicker capacities with hundreds of pounds of braking force. I don't think I require powerful bicycle-braking springs or fixtures either - the sorts found inside other switches or ballpoint pens would probably work fine.

    Any thoughts?

    lol, and because it's such a ridiculous approach - any better ideas?
    My mind says Technic, but my body says Duplo.

  2. #2
    Why must hard drives fail together? TheMainMan's Avatar
    Join Date
    May 2008
    Location
    Canada
    Posts
    806

    Default Re: Tactile switch conundrum

    I think it would be feasible to do that way. Connecting to the switches on the exterior would likely be more of a challenge then at the motherboard as those would just need to be lined up correctly. The front panel doesn't technically need to even be a switch; a plunger mechanism directly linked to the cable with a limit stop to prevent it from coming too far out of it's sleeve would be enough. A nail in a tube with the pointed end flattened and a hole drilled through the flat part for the cable to attach should work. Add a spring between the head and the tube and it would return to the starting position like a momentary switch. Edit: Here's a diagram to detail what I'm trying to describe.



    Not sure if it would be easier but it might be more compact to use an Arduino and a bunch of servos. Then you don't have to worry about finding room for the bend radii of the bike cables.
    Last edited by TheMainMan; 04-06-2015 at 10:39 AM. Reason: added mechanism diagram
    TheMainMan

  3. #3
    Moderator TLHarrell's Avatar
    Join Date
    Jan 2012
    Location
    Morgan Hill, CA
    Posts
    1,143

    Default Re: Tactile switch conundrum

    Brass rod and tube would be useful and fun to work with. Most sizes will telescope and rotate freely without slop in the next size up. You could then use the inner piece to push against a switch, or place a cam mechanism on the end to turn against the switch. Of course, this could go way into the realm of steampunk and we don't want that sort of tomfoolery going on in here.
    I have a hammer! I can put things together! I can knock things apart! I can alter my environment at will and make an incredible din all the while! -Calvin

  4. #4
    Anodized. Again. Konrad's Avatar
    Join Date
    Aug 2010
    Location
    Canada
    Posts
    1,060

    Default Re: Tactile switch conundrum

    Yeah, I naturally thought of a microcontroller-controlled approach at first, but it seemed like the actuators/servos/whatever which actually push the mobo buttons would end up being mechanically bulkier than my stupid bicycle-brake idea. But any push-the-button gizmo which is electrically isolated from the mobo and won't obstruct a GPU card would work.

    Pure mechanical levers and telescoping armatures and gearing and stuff - made of brass, of course! - would look awesome in a steampunk-themed mod. But (for me) such stuff is a whole lot more involved than a microcontroller approach, I could easily build a digital watch but can barely figure out how a mechanical one works, lol. Different mobos will have different buttons in different places, too, so I need some flexibility in lengths and locations.

    I was hoping this would be a kinda common problem with a kinda common solution. I guess not, I suppose I'm just being fussy as usual, lol.
    My mind says Technic, but my body says Duplo.

  5. #5
    Will YOU be ready when the zombies rise? x88x's Avatar
    Join Date
    Oct 2008
    Location
    MD, USA
    Posts
    6,334

    Default Re: Tactile switch conundrum

    Just to state the obvious, I would make absolutely certain that the desired functions are not available via headers.

    Another possible option, depending on the style of switch, would be to use something like the below to tap the switch contacts (a lot of surface-mount switches have the contacts bare on the sides).

    http://www.digikey.com/product-detai...1311-ND/745102
    That we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours, and this we should do freely and generously.
    --Benjamin Franklin
    TBCS 5TB Club :: coilgun :: bench PSU :: mightyMite :: Zeus :: E15 Magna EV

  6. #6
    Undead Pirate d_stilgar's Avatar
    Join Date
    Mar 2005
    Location
    Philadelphia, PA
    Posts
    2,987

    Default Re: Tactile switch conundrum

    Quote Originally Posted by x88x View Post
    Just to state the obvious, I would make absolutely certain that the desired functions are not available via headers.

    Another possible option, depending on the style of switch, would be to use something like the below to tap the switch contacts (a lot of surface-mount switches have the contacts bare on the sides).

    http://www.digikey.com/product-detai...1311-ND/745102
    ^This. Many motherboards are going to give you headers to give you the same function when the motherboard is in a case. If you aren't going to solder, then I would go with a product like the one he linked to give you those headers.

    Post pics of whatever you do. It's going to be very Frankenstein if there aren't any headers.

  7. #7
    Anodized. Again. Konrad's Avatar
    Join Date
    Aug 2010
    Location
    Canada
    Posts
    1,060

    Default Re: Tactile switch conundrum

    The clip-leads are a good idea, but I don't think I can really use them without prying underneath the switch body and scratching up adjacent PCB traces.

    On my current mobo (Asus X99 R5E) there are no meaningful headers, no breakouts. The "ROG styling" means that everything on the PCB is slick and decorative (and a little garish) and "ugly" things are hidden, no direct access to circuits or components without warranty-voiding electrical mods. Basically generic cheapish SMT-style tactile switches with completely recessed leads, no solder points on opposite side of the PCB, no exposed electrical contacts other than the switch housing itself. A total of eight such switches, a few have different caps (and even internal LEDs), scattered across almost every corner of the mobo. Thanx a lot, Asus!

    I could solder onto adjacent scraped traces, or physically dismantle the switches to access the internal contacts, or just solder them entirely off the board. Then reverse my (re)work and do it all over again every time I swap in another mobo (even if same model). I was hoping to avoid wedding the mobo-chassis combinations (and avoid potential warranty-voiding hassles) with a less intrusive approach.

    I'm back to thinking about thin bicycle cable, fitted with a (electrically-gutted, spring-loaded) push-activated switch on the front end, a modified (electrically-gutted) Cherry MX enclosure piggybacking each tactile switch, some heatshrink to anchor things in a reasonably secure but non-permanent fashion. I guess it is gonna Frankenstein.

    Tiny push/linear actuators are available - too large or too expensive (not gonna pay $90 each, lol). I am half-heartedly thinking that it might be possible to construct suitable solenoid/electromechanical relays out of "clickers" from ballpoint pens, lol, the same ones I'd salvage push-springs from.

    Edit - just found these ...
    My mind says Technic, but my body says Duplo.

  8. #8
    Will YOU be ready when the zombies rise? x88x's Avatar
    Join Date
    Oct 2008
    Location
    MD, USA
    Posts
    6,334

    Default Re: Tactile switch conundrum

    Quote Originally Posted by Konrad View Post
    Edit - just found these ...
    Good find! Something like that was going to be my next thought. Just rig something up to clamp one of those on top of each switch at the appropriate gap, and voila! A lot of that leaning, personally, is just that I am a lot more comfortable with electronics and code than with mechanical bits.
    That we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours, and this we should do freely and generously.
    --Benjamin Franklin
    TBCS 5TB Club :: coilgun :: bench PSU :: mightyMite :: Zeus :: E15 Magna EV

  9. #9
    Anodized. Again. Konrad's Avatar
    Join Date
    Aug 2010
    Location
    Canada
    Posts
    1,060

    Default Re: Tactile switch conundrum

    Also found these ... I inquired about 6x6x4mm (tactile switch package size), they said "that's too small!", I said "how small can you make them?" ... and then Alibaba and I smashed into some sort of language barrier.

    Quote Originally Posted by x88x View Post
    Good find! Something like that was going to be my next thought. Just rig something up to clamp one of those on top of each switch at the appropriate gap, and voila! A lot of that leaning, personally, is just that I am a lot more comfortable with electronics and code than with mechanical bits.
    Agreed, my personal experience is that moving parts are always the first parts to fail. But this application is stupidly simple: buttons which push moving parts which push buttons lol, so it kinda seems like electrical-to-mechanical-to-electrical is probably overcomplicating things. Programmable digital microcontrollers and servos are definitely overcomplicating things. I mean, a stick with a handle might work just as well.

    Sometimes low-tech is actually the better way to go. If my Alibaba supplier and I remain mutually incomprehensible then I'm heading over to my local bicycle shop.
    My mind says Technic, but my body says Duplo.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •