Author Topic: Optical Buttons? (Read 12605 times)

tetsujin · « **on:** January 31, 2005, 03:19:00 pm »

Hey,

After playing a bit with leaf switch buttons and microswitch buttons I'm curious about the possibility of building an optical "switch" to mount on an off-the-shelf button. The goal being better reliability than a leaf switch with less audible noise and better feel than a microswitch. I'm planning to use translucent leaf-type buttons so I can light them, but I don't really want to use leaf switches because of the maintenance involved or the space required. I was thinking of building a microswitch housing for the leaf buttons, but it seems like it'd only be a little harder to go optical...

Has anybody tried building optical pushbuttons? Or are there any manufactured?

brandon · « **Reply #1 on:** January 31, 2005, 03:53:54 pm »

sounds like a good idea.. Im not sure why this has never been done before. (we've had optical joysticks for a while). It could even open up possibilities for buttons with multiple optic sensors sort of how 49 way joysticks work.. of course there is really no need for them I guess since no Mame game would make use of "analog" buttons but it would be cool for consoles hacks with pressure sensitive buttons like PS2.. at any rate, sounds very cool

ericball · « **Reply #2 on:** January 31, 2005, 04:19:28 pm »

It would mean you would have active components rather than simple passive devices. Each button would need an some kind of opto sensor, then probably an analog switch to isolate the normal switch circuit. So instead of two wires to each button (common + button), you need four (+Vcc & GND). It also won't be cheap, better to buy leaf switches.

Trimoor · « **Reply #3 on:** January 31, 2005, 04:36:55 pm »

This would be easy and cheap to do. Optointerruptors can be bought for less than $.50 each if you know where to look.
They would only need 3 wires each: +5v, ground, and output. The round is common for both emitter and detector. Remember to use resistors on the emitter.

They would also be silent.

Jakobud · « **Reply #4 on:** January 31, 2005, 05:59:06 pm »

Don't forget that Microswitches and Leaf Switches both serve as springs as well, so an absence of those in a button will make the button so it doesn't spring back up.

Paul Olson · « **Reply #5 on:** January 31, 2005, 06:04:07 pm »

@Jakobud Not sure about leafsprings, but microswitch buttons use a spring inside the button.

Paul

Hoagie_one · « **Reply #6 on:** January 31, 2005, 06:30:32 pm »

an analog button could be usefull for racing games that use an analog pedal.

tetsujin · « **Reply #7 on:** January 31, 2005, 06:44:21 pm »

Quote from: Jakobud on January 31, 2005, 05:59:06 pm

Don't forget that Microswitches and Leaf Switches both serve as springs as well, so an absence of those in a button will make the button so it doesn't spring back up.

Yeah, I thought of that.

The buttons in question do have their own springs, and don't depend on the upward force from the switch, but the upward force of the button's spring is certainly supplemented by the leaf switch itself. The button still springs up, but with a little less force. I do wonder whether from a gaming comfort standpoint whether a leaf switch button with no leaf switch will be springy enough for good gameplay. I think they'll probably be OK, but we'll see.

I don't think I'll be building any optical analog buttons.

NoOne=NBA= · « **Reply #8 on:** January 31, 2005, 07:20:27 pm »

MOST of the resistance and return force, in both types of buttons, is provided by the switches themselves.
I've run buttons with the internal springs removed, and there is little noticable difference.
On the other hand, set your leafswitches so that the button is not right at the end of them sometime, and see how long it takes you to get cramps in your fingers from having to push so hard.

That said, I haven't had to do ANY maintenance on my leafswitches, other than the initial adjustments.
They just don't take that much abuse in a home environment.
I've got cabs with 20 year old leafswitches in them, and they function perfectly.
You may need to clean the contacts initially when you get them; but they shouldn't wear out, or become unreliable, in a home environment.
They just don't get that much use in a home environment.

I prefer the leafswitches because they can be set so that it requires almost NO pressure whatsoever to trigger them.
I do make custom mounts for my leafswitches however.
These mounts put the center of the button ALMOST to the end of the switches.
This allows the lightest touch possible to trigger the button.
Once you have that, if you adjust the top leaf so that it touches the button at rest, and the lower leaf so that it ALMOST touches the top leaf, ANY pressure you put on it will trigger the switch.
This contrasts sharply to the microswitch buttons, which don't contact until the switch is almost to the end of its travel.

My thought is that optical switches will fall closer to the microswitch feel, than to a properly adjusted leafswitch.
This is because you will have to have enough travel in the switch for the interrupter to COMPLETELY break the beam on the opto-switch, and then travel far enough back up to allow normal operation.
It may be possible to adjust the interrupter so that it gets closer to leafswitch travel by allowing it to partially block the sensor; but I think this would also create a condition where they would start becoming unreliable.

Trimoor · « **Reply #9 on:** January 31, 2005, 08:09:00 pm »

I disagree. Optical sensors can be found with a very narrow beam suitable for this purpose.

Why not try hall effect sensors? They detect the proximity of a magnet, and switch on accordingly. They can have a very narrow threshold, and wouldn't require a complex holder. Glue a tiny magnet to the end of the button, and put the sensor the right distance away from it. You can even get analog sensors if you really want.

NoOne=NBA= · « **Reply #10 on:** January 31, 2005, 09:10:04 pm »

I thought about a magnetic setup, but again I think they would prove very finicky in the "almost closed" range.

I'll stick with leafswitches because I haven't seen any way you can really IMPROVE on their performance.
I want a switch that you don't even have to MOVE to make/break contact.

I think the primary problems that people have with leafswitches are dirty contacts, or improper adjustment.
If you take a little time to set them up properly, they are the most reliable and sensitive switches I've ever played with.

tetsujin · « **Reply #11 on:** January 31, 2005, 11:24:09 pm »

Quote from: NoOne=NBA= on January 31, 2005, 09:10:04 pm

I'll stick with leafswitches because I haven't seen any way you can really IMPROVE on their performance.

Thanks for the feedback, you make a good argument in favor of the leaf switches. I'll definitely give them a chance. I'm still interested in trying the optical button idea, though.

NoOne=NBA= · « **Reply #12 on:** February 01, 2005, 12:06:54 am »

I'm all for trying stuff.
That's how I learned to tune leafswitches to exactly where I wanted them.
I had to build my own "custom" mounts to do it.
The mounts are actually just a piece of wood at just the right thickness to put the leafs where I need them.

stevejt · « **Reply #13 on:** February 01, 2005, 09:37:22 am »

I can't see any reason for optical buttons. They would not be any quieter like stated above. Leaf SWITCHES make no noise if adjusted close enough. The noise is from the moving part of the button htting the button housing. The same noise would be present with optical sensors. Any padding or changes that could be added to quiet a button using an optical sensor, could be added if using a leaf switch. Why would you want to add time, money extra wiring and just more options for possible failures/diognostics, without having any benefit? As far as optics for an analog button- I think that would be pretty hopeless. How many fine tuned optic sensors could you get to work reliably in less than a quarter inch of travel? That still would NOT be analog. The exact same thing could be done MORE accurately and more RELIABLY making your own leaf switch using multiple contacts and spacers. I can't see a single benefit for optical buttons.

Steve

tetsujin · « **Reply #14 on:** February 01, 2005, 10:34:45 am »

Quote from: stevejt on February 01, 2005, 09:37:22 am

I can't see any reason for optical buttons. I can't see a single benefit for optical buttons.

I understand your concerns, but they are irrelevant to the technical questions at hand: whether it's been done, whether there are any serious obstacles to making it work. If you don't see the need for optical buttons, then you needn't concern yourself with my efforts to experiment with them.

If you haven't built optical buttons then I seriously doubt your ability to judge their practical characteristics.

I have absolutely no interest in making analog buttons. I think it could be done by using a filter with varying levels of opacity in different positions, then taking analog measurements from the phototransistor. But given the extra work required and the fact that I have no software that would make use of it, there's nothing in it for me.

Don't get me wrong, it's not like I think this is necessarily going to be the best thing ever, it's just something I think would be fun to try. Even if I get it to work it might not be worth the effort to use it in my control panel. But on the other hand, it might. As I said I expect they'll have quieter operation than microswitches and better reliability than leaf switches. (Though my concerns about leaf switches may be ill-founded. I have very limited experience with them.) If they don't work I can replace them with leaf switches. Or microswitches.

"People who say it cannot be done should not interrupt
those who are doing it."

RayB · « **Reply #15 on:** February 01, 2005, 11:12:45 am »

Quote

If you haven't built optical buttons then I seriously doubt your ability to judge their practical characteristics.

That wasn't really a fair response, given that your original intent was coming up with a noise-free solution. He was correct in saying that you'd get the same amount of noise from the button plastics and spring.

But anyways, on to what I really had to say regarding "analog" buttons:
There is a company that manufactures a "circuit" where the harder you push on the contact point, the resistance changes. I saw a sample of this back in '94 when I was working at a game company. Anyways, the "circuit" was really flat, so I guess they designed it to be stamped onto circuit boards.

The point I'm getting at is this would probably be a better solution than optical, since measuring the resistance would directly relate how hard a button is being pushed. (Unless you're more interested in how FAR it's pushed--more like a throttle?)

I THINK Sony PS2 controllers use the circuit I described above...

HEY I found it! Here it is: http://www.tekscan.com/flexiforce/flexiforce.html

NoOne=NBA= · « **Reply #16 on:** February 01, 2005, 01:30:58 pm »

I've actually tried to quiet microswitch buttons using a variety of damping materials inside the button itself.
I used cotton, foam, etc... inside the button, and it did help to some extent, but also created more resistance from the damping material pressing against the internal parts on the button.
In the end I determined that the lower noise was not worth the added resistance.

As far as reliability goes on leaf-switches, consider that almost ALL arcade machines prior to the late 80's used them--in arcade environments.
There isn't a much more demanding situation I can think of than the fire button on an Asteroids machine in the early 80's.
I played the SAME machine in a grocery store near school for FOUR years, and they never had a tech out to fix it.
This was not an arcade machine with a tech on site to fix it, and got hammered for at least 8 hours EVERY day.

-----------------------------------------------------

RayB,

You've got much more manly fingers than I do.
I don't want to push ANY button repeatedly in the 5-15 lb. range.

tetsujin · « **Reply #17 on:** February 01, 2005, 01:46:01 pm »

Quote from: RayB on February 01, 2005, 11:12:45 am

Quote
If you haven't built optical buttons then I seriously doubt your ability to judge their practical characteristics.

That wasn't really a fair response, given that your original intent was coming up with a noise-free solution.

It absolutely was. My concern with noise was in relation to microswitches, where the switch itself is a significant source of noise. stevejt also implied that optical would be more failure-prone than leaf switches. Which is possible, given that it's a more complicated solution. But it'd also be mostly solid-state, whereas leaf switches contain moving parts that need to make electrical contact. The real answer to optical buttons' reliability is to be determined through testing, unless someone who's built or bought one is going to tell me not to bother...

Mostly, though, I just take exception to responses of the form "you shouldn't try that". It's entirely possible that he's right, that there will be no practical advantage whatsoever to an optical button, but telling me there's no point in trying this doesn't help me to get it done, you know? And what if he's wrong? What if I listened to him when he told me not to bother trying it? Then I'd never know.

NBA: I have played games in the local arcade which had some dead-buttons. Whether they were microswitch or leaf, and why they failed, I can't say. Whether they would have done better or worse with optical buttons, I also can't say.

NoOne=NBA= · « **Reply #18 on:** February 01, 2005, 02:21:28 pm »

The best optical vs. leafswitch comparison I know of is Tron vs. Gorf.
They used the same joystick TOP, but different bases.

Tron used leafswitches, very similar to the Pac sticks.
Both of them held up very well in arcade environments.

Gorf used an optical approach, and had two sliding "cards" on the bottom that interrupted optical sensors to determine stick direction.

Both of these approaches worked well in practice.

-------------------------------------------------------------------

My comment about button failure was not that it doesn't happen, but that it is not the widespread epidemic that everyone tries to make it out to be.
Buttons DO fail, but they don't go out left-and-right on a daily basis.
Given that alot of arcade machines saw more use in a year than most home machines will see in their lifetime, button failure is not that big a deal.

On a personal note, I've had a few microswitches fail on me in my cabinet, due to the mechanisms getting sticky INSIDE the switch.
A couple were bad straight out of the box.
When this happens, there's not much you can do, but throw them away and get new ones.

By contrast, I've NEVER had a leafswitch fail--even the ones that are 20 years old.
it's just really hard for a leafswitch to flat-out fail.
There are moving parts, but the simplicity of those parts is such that, unless you WEAR them out, they will keep working.

It's two pieces of metal.
As long as those two pieces can create/break contact, they work.
You may need to clean the contacts for optimal performance.
You may need to adjust them to lessen button travel.
But all-in-all there isn't really anything there to BREAK.
Even when the contacts get worn down to nothing, the leafs themselves will continue to open/close the circuit--albeit not as reliably as the contacts.

u_rebelscum · « **Reply #19 on:** February 01, 2005, 03:12:24 pm »

Quote from: tetsujin on January 31, 2005, 03:19:00 pm

I'm planning to use translucent leaf-type buttons so I can light them...

Has anybody tried building optical pushbuttons? Or are there any manufactured?

One big thing you'll have to be careful is not to mix the button lighting with the optical emitter light.

You can get optical sensor/emitter combos for ~ $1 at newark.com or mouser.com with 0.5 mm movement (horizontal) from min to max sensor lighting. Most PC mice have even a smaller gap (have you seen how fine the teeth are on some of those mice's encode wheels?), but don't have the shielding like the ones ref'ed above.

A good thing to do is to pass the output through a transistor so the "open"/"closed" boarder is sharper (assuming you want normal digital buttons). A resistor to adjust the exact open/closed point (for smaller than 0.5 mm, otherwise you need to move the sensor), and maybe a cap to help stop bounce (although most BYOAC keyboard encoders cover bounce). Take a look at an Atari, Wico, or Betson TB circuit boards for ideas how to wire (but not the new red happs boards or even the slightly older green, as they are much more complicated).

An optical button isn't that hard to make. I'm not that picky about buttons, however, so I'm not the one to ask "which is better" opinions about button switches.

FWIW, digital Halls Effect switches (yes, digital, not analog) run about the same or a little cheaper than the optical sensors, but minus a magnet.

As far as mame cares, it does not matter if the button switch is leaf, micro, hall effect, optical, piezoresistive, POT, or whatever. The easiest and most used in the arcades are the leaf and microswitches. You'll see a lot more optical, hall effect, and piezoresistive in industrial areas (but the piezoresistive is fairly widely used in gamepads).

brandon · « **Reply #20 on:** February 01, 2005, 03:32:37 pm »

how about using those little magnet reed switch..or I think thats what they are called.. Its a little glass tube that sort of looks like a tiny light bulb.. I think they use them for security alarm sensors.. they are totally passive as far I know and might work pretty well.. Actually.. now that I think about it I used to have a Sega Super Master Golf cab and it used a little swinging golf club controller that had those sensors in it.. hmm...

NoOne=NBA= · « **Reply #21 on:** February 01, 2005, 03:44:09 pm »

The Colecovision Super Controllers used them too, but they were terrible.
They had a trackwheel on them for running the baseball guys around that had a couple magnets on it, and alternately closed the switches on each side of it.
I've had to fix them on BOTH my controllers.

They may have been a bad batch though, so off-the-shelf ones may be more durable.

RayB · « **Reply #22 on:** February 01, 2005, 03:49:20 pm »

Quote from: NoOne=NBA= on February 01, 2005, 01:30:58 pm

RayB,
You've got much more manly fingers than I do.
I don't want to push ANY button repeatedly in the 5-15 lb. range.

<off-topic>
NoOne,
You ever played the ORIGINAL version of Street Fighter, with the big rubber buttons? Man did my arm get sore on that thing...
http://www.klov.com/game_detail.php?letter=&game_id=9803
(and THERE's a cool cab to MAME...

OSCAR · « **Reply #23 on:** February 01, 2005, 06:04:41 pm »

FWIW, Perfect360 used to make optical pushbuttons and were sold through Wico, but I believe they were discontinued when Happ bought the rights to the Perfect360 technology. I seem to recall operators hating the P360 buttons due to reliability issues. According to the old catalog listing, however, they were "spill proof"...

tetsujin · « **Reply #24 on:** February 01, 2005, 06:18:18 pm »

Quote from: OSCAR on February 01, 2005, 06:04:41 pm

I seem to recall operators hating the P360 buttons due to reliability issues.

Hm, not encouraging. Thank you for the information.

stevejt · « **Reply #25 on:** February 02, 2005, 09:33:45 am »

I was not "concerned". I was just stating I don't see any benefit. As far as doing it just because it hasn't been done, I think that's awesome. I just thougt it silly (I'm sure I do many (many, many) things the rest of the world sees as silly), to go through the manufacture of a control panel worth of buttons, without having any benefit.

Quote

If you haven't built optical buttons then I seriously doubt your ability to judge their practical characteristics.

Unless I am missing something, you haven't YET either. So if your statement is true, than you don't have any ability to judge their pratical characteristics either.

(You don't need to be shot to know it's gonna hurt.)

question: you said analog measurements from the photo transistor. My knowledge of electronics is basic. I know the measurements from a CDS cell are varible, (and I know, designed mainly for visible light). I thought infrared detectors were more towards the digital side. Is a photo transistor exactly the same as an infrared detector? I am asking because transistors give variable readings, but have 3 leads. Infrared detectors have 2 leads. (Wheel sensors have 3 leads for 2 sensors for sensing direction.) This is an honest question, since you seem to have knowledge on the subject.

I never said, or even hinted that it couldn't be done. I just said extra work, extra wires, extra voltage, more parts to fail, with no BENEFITS. As leafs are reliable. Though some work, micro switches can be quieted by opening them, and bending the contact,(in the right spot) to lower the distance of travel the contact makes when the "snap" is made. Something could also be put between the NC contacts, that would leave less distance between the NO's.

If you complete this, which mechanically I do think is simple, I am sure everyone, INCLUDING MYSELF, would love to see some close up pics. I am sorry if I still don't see any benefits outweighing the extras.

(BYW- my reply seemed to piss you off some,(even if just a little), it was nice to see such a strong response, not be rude. What I call a "polite STFU".

Steve

tetsujin · « **Reply #26 on:** February 02, 2005, 10:12:42 am »

Quote from: stevejt on February 02, 2005, 09:33:45 am

question: you said analog measurements from the photo transistor. My knowledge of electronics is basic. I know the measurements from a CDS cell are varible, (and I know, designed mainly for visible light). I thought infrared detectors were more towards the digital side. Is a photo transistor exactly the same as an infrared detector? I am asking because transistors give variable readings, but have 3 leads. Infrared detectors have 2 leads. (Wheel sensors have 3 leads for 2 sensors for sensing direction.)

I should really try not to get so pissed off all the time.

I've got to remember why I'm here talking to knowledgable, experienced people instead of doing my work in total isolation.

In fact, now that you mention it, it is possible that it wouldn't be possible to take analog readings from the phototransistor in an opto-interruptor module. Different transistors have different characteristics, and some are less inclined toward analog behavior than others.

The reason phototransistors generally have two leads instead of three is because the third is replaced by the optical sensor.

The IR sensors in most IR equipment are, I think, generally IR phototransistors. Certainly the ones I was looking at at All Electronics are, according to the spec sheets.

stevejt · « **Reply #27 on:** February 02, 2005, 11:07:13 am »

Quote from: tetsujin on February 02, 2005, 10:12:42 am

Different transistors have different characteristics, and some are less inclined toward analog behavior than others.

The reason phototransistors generally have two leads instead of three is because the third is replaced by the optical sensor.

Thanks. Well explained.

I'm sure your "polite stfu" must have entertained a few. As much as they were inapropriate, Subzero's immature comments and arguments were at the very least, entertaining. I actually feel bad to be the one he was arguing with when he finally got banned. But I guess it was coming to him anyway.

Steve

This reminds me of BBSing. When some boards had the "war zone" thread. Gotta love that!
Any one who doesn't know what I'm talking about, you missed out!

NoOne=NBA= · « **Reply #28 on:** February 02, 2005, 03:51:32 pm »

The key here is to think of this as a brainstorming environment.
You throw out a "what if', and people respond with "but, but, why not...".

From that you pick what helps YOU, and ignore the rest; or respond back with your own "but, but, why nots...".

If you think of the board here as a big swirling pool of knowledge, experience, and mistakes, it will help keep you on a little more even keel.

Alot of people here have tried ideas that you might have; and will try to talk you out of doing things, or into doing them a simpler way, because they've made mistakes doing what you are attempting.
If you look past the "don't do its", and concentrate on the "here's what I did wrongs", you may be able to succeed where they failed.
If you decide to "do it anyway", at least you were forewarned.

Alot of times people here will just play Devil's Advocate in threads to help the person think things through before starting, and presolve as many problems as possible without wasting time/money.
That's the case in most of this thread.
People are all shooting out ideas, actually related to different goals (analog/digital/optical/mechanical/etc...).
YOU need to pick the knowledge out of it that helps you succeed in whatever you attempt, and retain the rest for future reference to whatever extent possible.

ShinAce · « **Reply #29 on:** February 07, 2005, 05:40:14 pm »

Stay tuned....
In a few weeks time, I'll have built such a beast.

ShinAce · « **Reply #30 on:** April 25, 2005, 09:57:38 pm »

Update:

My sister moved back into town unexpectedly, but I've finally gotten around to converting a pushbutton to optical. The idea was just sitting on a breadboard at first.

I now have 7 optical microswitches that I can plug and swap into pushbuttons. The photo-transistor and LED are just hanging off the body of the microswitch(held by their soldered leads), yet it still slips into a pushbutton like any other switch. I've used all 3 tabs: one for 5 volt, one for ground, and finally the third is an active signal. The signal is analog and throw sensitive. But I'll pass it through an IC, convert it to true digital and clean it up.

I'll be back with more in a few days, I still need to build the case.

EDIT: I've drawn up the schematic so that you peeps can see how this was done. There's a schematic clearly showing the electronic aspect. Then there's a diagram showing how I chose to wire it to a switch.

www.geocities.com/alainprice/diagram.jpg
www.geocities.com/alainprice/schematic.jpg

I'm going to wait until I get a chance to install the switches and play a few games before posting pics and comments. So far, they're great. The sensitivity can be adjusted in a number of ways. Each one draws under 3 mA, and they can be hot swapped for on the go fixes. But what are the odds of an optical switch needing replacement?

ShinAce · « **Reply #31 on:** April 28, 2005, 11:31:34 pm »

And some pics. These things are crude, but show much promise.

IntruderAlert · « **Reply #32 on:** April 28, 2005, 11:39:50 pm »

What's inside the modified microswitch now?

ShinAce · « **Reply #33 on:** April 29, 2005, 08:13:31 am »

A 10k resistor between COM and NO. The normal guts have been removed.

IntruderAlert · « **Reply #34 on:** April 29, 2005, 08:35:39 am »

..can't wait to hear how your tests turn out

ShinAce · « **Reply #35 on:** May 04, 2005, 12:40:52 am »

It works great. I'm buffering the signal with a schmitt inverter. The part number for that is 74ls14. I'm using a 54hc14, which is the same thing but in military specification.
Nearly everything worked out perfectly from the get go. At first, medium punch would jam, but then I realized it was because of the inverter. It'll switch when you get past, say, 2 volts, but won't switch back until you get below a volt. It turns out the medium punch LED was a little off center, so I bent it in place and off I went.

It doesn't feel awkward for me, it's kind of nice. Quiet, too. Just remove the microswitch from a pushbutton and that's what it's like.

IntruderAlert · « **Reply #36 on:** May 04, 2005, 10:58:04 am »

now all you need to do is start mass production and distribution

..and don't forget to get your patent

ShinAce · « **Reply #37 on:** May 04, 2005, 06:45:37 pm »

I could build the optical switches, and they can be directly plugged to a pad, as long as you give them 5 volt power. But since I'm using the schmitt trigger as a switch debouncer, the whole situation becomes more complicated.

But if someone wants to try it on their own, they'll need an OP550(A or B or C or D), I used the OP550A as well as some high intensity red LED's. Add an unwanted microswitch and 2 resistors, and you're done. The microswitch should be free, since you don't need a working one. The resistors are worth roughly 5 cents each, the led is worth about 25 cents, and the photo-transistors are 1$ each. So it cost me under 2$ per switch, assuming an unlimited supply of free microswitches.

spiffyshoes · « **Reply #38 on:** May 09, 2005, 12:26:08 am »

Where would you suggest getting the parts? And could you make a tutorial on what needs to be done to the microswitch to add these and how to hook them up to a pad. I'd assume you could hook them up the same way you do a P360 just supply the +5v from the pad and then the ground and live wires like normal.

ShinAce · « **Reply #39 on:** May 09, 2005, 05:02:48 pm »

You can get the high intensity red led's, 1k resistors, 10k resistors at any local electronics store. The OP550A can be had from digi-key, mouser, or possibly fry's. I got mine locally for 1,25$ a piece, canadian.

The way the circuit is wired, it's backwards. So it would work properly if you held all buttons and let go of the one you want pressed. So I fixed this problem and debouced the switch in one shot. I used a 74ls14(or 7414, or 74hc14, even 54hc14) to invert the signal and keep the switch from having a strobe effect when held halfway. In a pinch, you can use a 74ls04, but it doesn't eliminate the bouncing effect(in theory at least).

The one it's done in the pictures, COM is 5 volt, NO is the active signal, and NC is ground. You can rewire it if need be, but for the pieces I had, this placement was ideal.

www.geocities.com/alainprice/opticmod.zip


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