[Guide] Fix burnt out gear lights, led conversion!

[Guest]

parts list: 5mm led's (they come in multiple colors) http://www.ebay.com/itm/100pcs-5mm-T...QAAOSw~bFWLbbo


And a resistor... which i will tell you how to figure out what value you need!

My led's package says that its voltage is 3.1-3.4v at .02 amps

First we need to figure out the leds internal resistance
Through V=IR we get 3.4v= (.02A)(Resistance) = 170 ohm

Now our bikes when running can peak (at a number to be safe) 15v

Now when you know that use the voltage divider calculator http://www.raltron.com/cust/tools/voltage_divider.asp or do it by hand

plug in 15v for the input voltage
leave r1 blank (thats what were solving for)
r2 = the resistance of the led (calculated above)
V out = (should be specified) mine is 3.4v

and you should get a value for r2, mine was 580 ohm

(i dont exactly have a 580ohm resistor, so i used a 1000ohm resistor)

the idea is as follows
1.jpg
The circuit works by supplying one + rail to 6 grounds (the gears on the bike)


Start by de-soldering the old connectors (sorry i dont have a picture of what it looked like before)
but the connectors look like this



Now place the leds onto the board(mine was a common 12v and 6 grounds, the orange wire supplied the power)

the longer leg on the leds is the positive side (very important)

place the leds onto the board like this




Solder them up and trim the leads (should look similar to this when done)


(i crimped the resistor in parallel with the voltage supply, dont have a picture of that sorry)

and here is what the final result looks like

[80GS850GBob]

Very nice work.
...I like using this LED array calculator for my O scale and Sci Fi model stuff- http://led.linear1.org/led.wiz

btw...1/4w resistors?

[hockey911]

Yes, im using 1/4 watt resistor, i dont see much of a reason to use one when i have a 1k ohm resistor on it