Mounting LEDs in translucent happs pushbuttons (joymonkey?)

[juggle50]

Just wondering how you guys do this.  I've heard that you want to drill a 1/4 inch hole in the bottom and use the black ring mounting pieces from Radio shack.  However, when I drill the bottom I get a lot of excess plastic that seems to get in the way.  Also, The black ring pieces seem to cover a lot of the side of the LED and I'm wondering if that loses light.

Thank you for your help

[ShinAce]

You can always drill a 3/16" hole and push the LED in hard enough that it jams.

[MovingTarget]

I'm mounting 2 LEDS in mine but not from the bottom and not using the Radio Shack piece you're talking about.

Drilling holes on the sides directly into the threads.  Basically you need to be careful where you do this because you don't want to drill into plastic in side that goes up and down when the button moves.  I will be drilling as close to the bottom as possible.  

I've already done up one button for test purposes.  The only problem I've found is I will have to do some additional material removal when mounting to the control panel (3/4" mdf) because the button nut needs to go on first and it needs enough room to clear where the holes are at the bottom.

I did try mounting one LED in the base of the button (didn't use the Radio Shack part), it mounted in great but the top of the button was like a flashlight and I was blinded if I looked directly down at it.

2 LEDS on the sides gave the best effect.  I imagine similar to what the results were for the WICO buttons used on the NEON MAME.

I'll post some pics if you would like.

[JoyMonkey]

Basically you need to be careful where you do this because you don't want to drill into plastic in side that goes up and down when the button moves.

FYI, the 'plunger' part of the pushbutton that actually moves is easily removeable. You should take it out before you drill; that way the button won't fill up with plastic shavings.

[MovingTarget]

How?  I tried to remove on one of my buttons by prying the top of the button (part that you push) but stopped when if felt like the button would get damaged.

Even if you remove it you need to be sure not to drill where the plastic part inside the button body goes up and down because the LED will be sticking into the body and that would mess with the physical movement within the button.

[ShinAce]

The plunger is exposed at 2 places, a flat circle for your finger to press, and 2 little tabs on the other side(that hit the microswitch). You just push the tabs towards the inside and push it in. Now you can grab the circular part of the plunger and easily remove it with 2 fingers.

Putting it back in is easier. Compress the spring, and squeeze the 2 tabs together, now slide it into the button.

[juggle50]

Moving target, what was the viewing angle rating of your LED's?  Mine is 45 degrees so I'm hoping to not get the flashlight effect.  Joy Monkey, I think you said that worked pretty well.

When I drill the hole in the button the plastic curls up in the button.  Anybody else have this problem?

[MovingTarget]

I see nothing that came with my LEDs that say what the viewing angle is.

You should try hooking one up through the bottom to see if you get that flashlight effect or not.  Hooking the LED to a 9v battery worked for me but I had a few extra LEDs in case I ruined it.

I did try JoyMonkey's method of removing the plunger on the button and it worked so you should do that to get that curly plastic garbage out of the button that was created when you drilled the hole.  In all the drilling I did I easily got the excess out without removing the plunger but maybe I was just lucky.

[JoyMonkey]

I've found that the 45

[JoyMonkey]

Hooking the LED to a 9v battery worked for me but I had a few extra LEDs in case I ruined it.

NEVER HOOK-UP AN LED DIRECTLY TO A POWER SOURCE WITHOUT FIRST PUTTING AN APPROPRIATE RESISTOR IN-LINE.

Read up on how LEDs are supposed to be used.
And use this calculator to figure out what kind of resistor your LEDs require.

[juggle50]

Joymonkey,

You rule.  Thank you very much for taking the time to do that tutorial.  Excellently done and it should be posted to the FAQ's somewhere. 

Have you ever tried sanding the tops of the LED's?  I've heard that that also disperses the light.

[ShinAce]

Wow! A picture is worth a thousand words.

Having done this type of thing many times, I take for granted that instructions are hard to give. Although the first step is unnecessary, you can skip it and go directly to the second pic.

Props on the 3/16" drill bit recommendation...

And now I'd like to give a quick word on LED's. Think of an LED as a switch, because it IS a switch. So let's say you have a red diode rated for 1.9 volts forward drop and 20mA. This tells me that below about 1.5 volts, the LED will prevent any current from flowing, the LED will be off. But once you go above 1.9 volts, the LED lets ALL current go through. It does not limit current in any way. So if you are working with 5 volts, you know the LED will use 1.9 volts and wants a max of 20mA. Now you just need to find a resistor that drops (5-1.9)=3.1 volts and allows 20 mA of current.

R=V/I
If I(current) is always chosen to be 20 mA, the formula becomes
R=50*V
R=50*(3.1)
R=155 ohms, the closest value is 150, so use that.

This is assuming a 1.9 volt drop for the diode, 5 volt source power, and 20 mA current.

Please, if you choose to connect an LED directly to a voltage source, do not tell us about it. You are hurting the community by spreading such disinformation. I myself connected a green LED to a 12 volt battery just to see how bad it would be. The LED was shining red, not green, and I measured 250 mA of current. It burnt out in roughly 5 seconds.

[JoyMonkey]

Have you ever tried sanding the tops of the LED's?  I've heard that that also disperses the light.

I haven't tried that since my LEDs fill the buttons with light well enough without any modification. I can see how it would work though, if you've got LEDs with low viewing angles.

[JoyMonkey]

Just for completeness sake, here's the drawing I did from another thread that illustrates how important the viewing angle of an LED is when you're mounting them this way.



You can see how an LED with an acute viewing angle would create an extreme hot-spot in the center of the button (and can be almost blinding if the LED has a high MCD rating). An LED with a larger viewing angle and lower MCD will light up the button much more uniformly and will be less likely to blind your friends.

As Randy has pointed out before, when you're mounting the LEDs so they're pointing straight up through the button (like in the above drawing) the most important factor in choosing an LED is it's luminous flux, which is determined by it's MCD and beam angle.

Here's a nice calculator to help you easily figure out an LEDs luminous flux:
http://led.linear1.org/lumen.wiz

While I'm at it, here's another useful calculator for determining what size resistor each LED needs:
http://led.linear1.org/1led.wiz

[MovingTarget]

Hooking the LED to a 9v battery worked for me but I had a few extra LEDs in case I ruined it.

NEVER HOOK-UP AN LED DIRECTLY TO A POWER SOURCE WITHOUT FIRST PUTTING AN APPROPRIATE RESISTOR IN-LINE.

Read up on how LEDs are supposed to be used.
And use this calculator to figure out what kind of resistor your LEDs require.

Actually I did have a resistor attached to the LED when I did this.  Should have mentioned that too I guess :/

Also, please don't take what I said out of context.  I was suggesting that he should test his LED in his button to see if he liked the results.  This was for a quick easy (that's why I suggested the 9v) test and not a permanent solution. 

Also, my LEDs must be the more narrow angle ones, they are blue 8000~10000 mcd 20ma.

[Hockeyboy]

This is great info...I'm an electronics tech and this is still great information to pass around. Thanks!

[Level42]

Uhmmmm, can we have a picture of the results please ? Like to compare them to my lit (Knievl-style) leaf buttons.

[JoyMonkey]

I have some translucent red leaf buttons sitting here; if I have time (and room) I'll wire one into my test panel beside a translucent red microswitch button to give a side by side comparrison. I only have 45

[JoyMonkey]

Crud! I went to install a couple of the leaf buttons but realized that I don't have any pal nuts. Also, my button holders are black; so they wouldn't be recommended for a lit button. Time for another Bob Roberts order I think...

Anyways, here's some photos of the translucent microswitch buttons, with LEDs installed per the instructions above. It's really difficult to get a good photo of these, does anyone have any recommendations?

Photos taken with flash in a moderately lit room:


Photos taken without flash in a moderately lit room:


Photos taken without flash in a dark room: