Which way to wire LEDS in my buttons?

[MovingTarget]

I've got 10 Happ Tranlucent buttons that are blue.  I've got some blue super bright LEDs I believe they are 20ma and a lot of resistors.  I want to mount 2 LEDs in each button.  I've already figured out where to place the LEDs and have the holes in the buttons. 

Also, I've got a Happ Trans track ball that I'm going to run 3 LEDs to.  So that's a grand total of 23 LEDs.

My plan is to wire this to the PC power supply.

Now I'm ready to wire it all up and I've got somewhat of a dilema.  My original plan was to have one resistor per LED and wire each one in parrelle.  However, I just read something that said wiring this way isn't reliable!

Also, I wasn't going to solder the ends to wires, was just going to twist them together. 

Looking for advice of those in the know.  Here is a picture of what I was going to do.

My questions are:

1.  Do I need to use one resistor per LED or can run more than one light off one resistor?
2.  Is it better to run in series?  If so how many LEDs per run?  Can I do all in the same run?  I didn't choose series because I was affraid if one when bad nothing would work.
3.  What's the easiest most reliable way to connect the LED to the wire?
4.  Is it okay to twist the resistor and LED legs together?

Thanks for any input.

Now for the crappy drawing/representation of what I was going to do...

[rdagger]

1.  If you wire in parallel it is best to use 1 resistor per LED.
2.  Personally I think parallel is the better way.  Less possible errors.  More consistent illumination
3.  Carefully, solder the wire to the LED.  Do not heat the LED too long.  Additionally, heat shrink tubing over the soldered wires guarantees a long lasting connection and no shorts.   A few drops from a hot glue gun can also be used (in addition to solder) to secure a connection.
4.  I don't see a problem with twisting, but you should still solder them for a reliable connection.

With so many LED's you might be better off using bussed resistors.  These are resistors with 1 input pin and multiple output pins.  You could use three 8 pin bussed resistors instead of 24 individual resistors.  Just buy a small perf board, 3 bussed resistors and some connectors (like an IDC header).

[MovingTarget]

Thanks for the input.  I've already got all the resistors and I'm super anxious to get this thing wired up so I'll probably stick with individual resistors to a LED.

I do have some heat shrink tubing...dumb question though...how do you heat it?

[whammoed]

Heat gun.  I have used a lighter in a pinch though.  Just don't get the flame too close. 

[rdagger]

I use a heat gun.  It is the easiest, fastest, safest and gives the best results.  Depending on the tubing, a powerful hair dryer might work.  If you are very careful you might be able to use a lighter, stove, candle, soldering iron or a propane torch.

[soulblazer28]

Ok here are two dumb questions. I am in the same boat with having all the parts but not knowing how to proceed. 

How do you go from one wire coming off the +12v to each LED + ?  Some sort of 'Y' tap? daisy chaining?

Also, i bought LED's off ebay that came with their own resistor. But one of my electronical engineer student friends calculated a much lower resistance than what the resistors are rated.  Is that going to be ok or should I just go out and buy the resistor closest to what the calculation dictates?  I've read that if the resistor rating is too low it will overheat, but what if its too high?

[whammoed]

Ok here are two dumb questions. I am in the same boat with having all the parts but not knowing how to proceed. 

How do you go from one wire coming off the +12v to each LED + ?  Some sort of 'Y' tap? daisy chaining?

Also, i bought LED's off ebay that came with their own resistor. But one of my electronical engineer student friends calculated a much lower resistance than what the resistors are rated.  Is that going to be ok or should I just go out and buy the resistor closest to what the calculation dictates?  I've read that if the resistor rating is too low it will overheat, but what if its too high?

Daisy or terminal block for the wiring.

Higher resistance is ok, the led will simply not be as bright.  You could try it out and get the lower ohm resistor if you need to.

[somunny]

I'm also preparing to wire up a lighted cp.  FWIW, here's the method I'm going to use.  It's a combo series/parallel array:

http://led.linear1.org/led.wiz

When you use the calculator set the output to wiring diagram.  That will give you an idea of what you wiring should look like.

Oh, and I would definitely say solder the connections, also.

Steve

[MovingTarget]

I'm also preparing to wire up a lighted cp.  FWIW, here's the method I'm going to use.  It's a combo series/parallel array:

http://led.linear1.org/led.wiz

When you use the calculator set the output to wiring diagram.  That will give you an idea of what you wiring should look like.

Oh, and I would definitely say solder the connections, also.

Steve

Okay, now I'm confused a different way.  I ran that wizard and it's saying connect the - from the LED to the resistor and that wasn't how I understood it should work.

Questions:

1.  Does it matter which way the current flows through the resistor?
2.  Does it matter which prong the resistor is connected to on the LED?  should it come off the + or -?
3.  I can't find the resistence for the resistors I bought.  I think they're 100 but not sure.  Looks to me like the colors are brown, black, black, black, yellow but could be yellow, black, black, black, brown (thus question 1).  I tried to figure this out using this link http://www.elexp.com/t_resist.htm but I don't get it.

HELP!!  My soldering iron is getting hot as we speak.

[RandyT]

Okay, now I'm confused a different way.  I ran that wizard and it's saying connect the - from the LED to the resistor and that wasn't how I understood it should work.

Questions:

1.  Does it matter which way the current flows through the resistor?

No.

2.  Does it matter which prong the resistor is connected to on the LED?  should it come off the + or -?

It shouldn't matter.  It just needs to be in series with the circuit.

3.  I can't find the resistence for the resistors I bought.  I think they're 100 but not sure.  Looks to me like the colors are brown, black, black, black, yellow but could be yellow, black, black, black, brown (thus question 1).  I tried to figure this out using this link http://www.elexp.com/t_resist.htm but I don't get it.

The "yellow" is probably gold, which is the tolerance marking for 5%.

It's sounds like 100ohm to me.  Brown, Black, Black , Black (multiplier) ends up as 100 x 1.   The confusing part is that the same value can be expressed, as it is on the 100 ohm resistors I have, as Brown, Black, Brown (multiplier), which is 10 x 10.

If you are unsure, check it with an ohm meter, but I think you have a 100 ohm there.

RandyT

[MovingTarget]

Randy, I think you're right.  I went back to the site where I bought the resistors and LEDs from and they only sell 100's not 456 or whatever the other value would be if I were reading it backward.

Thanks for all the info everyone, I'm ready to start soldering now!