Switching Lights on button from Bulbs to LEDs

[Jubbs]

Hi guys, if this is in the wrong place, I'm sorry it seemed to be the most appropriate place for this question.

I play a game called Pop n' Music, which a Japanese Rhythm game that use 9 large dome buttons that you press in sequence to the music.  I have an old home made controller that I bought used called a Ransai controller.  This controller has got to be at least 8 years old (just a guess could be older or newer), and I am currently remodeling it a bit.  It needed a new PCB and I just installed a Cthulu PCb, and then I have purchased Neutrik's USB faceplate so that I can have a presentable way to hotswitch the USBs.

Digging around, I remembered that this has lights inside but I never use it because the previous owner didn't have the ac adapter for it and I don't have 10 D Batteries laying around (that's right 10!).  I figure since I am messing around with the case I might as well upgrade some other stuff.  My intention is to turn these 9 3-watt bulbs in the buttons in to LEDs, so that they consume significantly less energy.  I know how to remove the bulb from the controller and I understand you can purchase an LED kit and solder it to the plug shaped points sticking out of the microswitch.  Where do I buy these LED's?  Also, once they are turned into LED's would it be possible to:  A) Use a different battery pack? Maybe less D's or  even AA's or something?  B) Be powered by a USB?  So one USB for the controller and one USB for the lights.  C) Use the Cthulu PCB so that they can be powered from the same USB that the controller uses?

Thank you for any help with this.

[matsadona]

There are a lot of different LED replacement lamps out there, and a pinball spare part web site is good place to start searching for them.

Yes, the current needed for the LED’s are significantly lower than a 3W filament bulb. Here is some math:

3W/12V = 0,25 A
3W/5V = 0,6 A

A typical LED is 20-25-mA = 0,02 A

The USB standard is 500mA current output, so it is perfectly fine to use as power source to a couple of LED’s.

500mA / 20 mA = 25

So, if there are 9 LED’s, you could probably hook it up on the same USB wire as the controller, since that probably doesn’t use that much power.

[Jubbs]

I don't really get the whole resistor thing ( I know what it is just not how to use it).  I was wondering if it was possible to buy LED's that can be plugged into the existing prongs.  Like this: http://www.paradisearcadeshop.com/button-leds/89-tropical-spotlight-12vdc-led.html.  I am not sure if that product would work.

I also found these: http://groovygamegear.com/webstore/index.php?main_page=product_info&cPath=83&products_id=267  .  But Again I don't get how I would  hook it up with the button with the resistor.

[nordemoniac]

The resistor is to make sure the LED(s) won't take too much power and burn out.

What you should do is find out how much that controller is using, and how much the recommended LED power is, and add it together.

F.ex. some LEDs don't want more than 10mA of power. With 9 of these, it's less than 0,1A added together. But if your controller uses 0,2A, the total will be 0,3A.

The LED could in a setting like this try to grab as much power as they can get, if there is no resistor. Meaning they will grab the last 0,2A from the USB as well, and be overpowered by 3 times!

But if you add a resistor which makes sure the 9 LEDs can't draw more power than recommended, you should be fine!

Remember than USB is 5V, and most LEDs have a forward voltage of 3.0-3.3V. Meaning you should have a larger resistor which deals with the extra voltage.

[Jubbs]

The problem is that this is a homemade controller and no longer really follows the standard stats of a Ransai (so many renovations since its creation).  How do I find out how much power the controller takes?  Is it just off the Cthulu pcb or do I use a meter of a sort?  Also how would I wire the led with the resistor?