Almost free trackball backlight

[Scottacus]

I built a multicade several months ago but never got around to building a backlighting system for the trackball, yesterday I took the time to do it.  I had a bag of clear LEDs that I had bought months ago so I built a test circuit for them using this program:

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

to calculate the resistor values for the circuit.  I powered the circuit using the +5v output from the cab's power supply but the LED's never lit up.  What the heck!*?&%   I checked out the Jameco part number from the bag and realized that they were IR LED's that I had bought as a back up for repairing my Gorf machine's broken optocouplers!   

I was now stuck without white LEDs, what to do?  I could go to Radio Shack and pick up some white LED's but was there something else that I could use that was cheap and onhand?  I then remembered that we had a strand of white LED christmas lights that had failed so I started taking them apart so see what the LEDs looked like.  I have seen several different designs of lights over the last few years as these LED lights have gained popularity but I never took the time to pull some apart to see how they worked.  This strand's lights looked like this:



Some of the LED's had very large resistors attached to them but the majority were just straight up LED's.  I made a montage of 5 LEDs with 100ohm resistors  in parallel and attached the perfboard under the opening in the bottom of the brackets that hold the trackball in place.  This is the result:



Now the Wayback Machine glows!  I also took the time to make a couple of other changes while I had the machine apart.  I rewired the power supply so that it doesn't shut off when the mains switch is turned off.  Now when the mains go off the marquee and monitor shut down but the trackball stays lit and the high scores don't disappear. 

I also removed the 100 ohm resistor that I placed on the ground of my volume control on this machine as well as four of them that I built for a local college's rec center.  This resistor prevents the user from turning the machine's volume all the way off.   I figured it would keep me from getting calls because someone turned the volume all the way off and "now the machines don't make any noise."  It worked well for most games but the 60 in 1's "Gunsmoke" title was still way too loud with only 100 ohms of resistance between the volume control and ground.  Now I can run the volume all the way down to off if I want to...

[theinkdon]

Thanks for pointing out that a lot of Christmas tree lights are LED these days, I tend to forget that when I need LEDs. 
You mentioned Jameco, so I thought I'd just ask if you know about AliExpress?  Or basically, any of the cheap (really cheap) Chinese stuff from eBay or even Amazon more and more.  I used to buy from Jameco, Mouser, Kigi-key, etc, but since discovering the Chinese stuff I've saved so much money.  Of course the shipping times are 3-4 weeks, but stuff is so cheap you just load up on assortments and you'll be set for a long time.
That trackball looks great, btw.

[Scottacus]

I have used AliExpress in the past because it is very inexpensive but the shipping time literally included using a "slow boat from China."  They also messed up my order by sending me an Arduino board when what I ordered was a PIC Kit micro-controller programmer...

[brihyn]

Thanks for the great idea. I now have a lit-up trackball.