LEDs

[FlyZ]

Hi

How do you wire multiple LEDs and a switch for lighting inside the case?

Thx

 

[FlyZ]

Plz?? Anyone?
I got everything done cept the light

 

[sitka]

Try a dual conductor wire and use as hot and common (just a loop)
strip insulation inline on each conductor and solder on leds in parallel. Make it look like a ladder with the leds the rungs. Make sure all the positives, led long tail, are on hot line. For 5 leds I found 500 ohm resistor works good. If you only have 1/4 watt resistors you may want to run two 1000ohm in parallel and then in series on the hot line so they don't burn out. You really need high intensity leds I think.. or you will be wiring till the cows come home to get enough light.

 

[etech]

FlyZ, it depends on what type of LED you have.
simplified a little

two main type of LEDs.
1) Has a voltage rating, ususally does not show the current. Has the dropping resistor built into the resistor. The voltage is usually 3.3V,5V or 12V. For these all you would have to do is wire them in parallel, like a ladder with the LEDs being the rungs. As long as your wire can handle the current it does not matter how many you put on the string.

2) Does not have a dropping resistor built in. Spec will be something like 20mA @ 1.2VDC. This will be a little more interesting. The easy way to do it is to add a dropping resistor for each LED. There is some leeway as to the current so you pick the closest standard resistor that you can find.
ie. 5V rail, and the resistor above.
5 - 1.2 = 3.8v which is the voltage the resistor needs to drop. You want 20ma through it. E=IR(voltage = current*resistance)
gives 190 ohms for the resistor value.
So you would put a 190 ohm resistor in series with each LED on the string.

OR, calculate one resistor value to be placed in series with all of the LEDs as sitka has advised. Watch the power- P=IIR Watts = Isquared * resistance. It adds up quickly.

The calculation is the same as for the individual resistors. Find the voltage(from LED specs) you need to drop across the resistor. Add up the current for all of the LEDs you plan to wire in and calculate a resistance value.