Make your own moon lights for less than $1

carmexx

Active Member
Thank You very much.... I think i am gonna try to tackle this DIY.......so if I wire LEDS in parallel will the voltage stay the same?
 

KodiakBear

Active Member
you can expect a 3.1 - 3.8V drop across an LED. if you connect them in series, you just add it up. in parallel all the circuit sees is the one voltage drop.
You have to be cautious about this because the net resistance of a parallel circuit is a lot lower than if you only had 1 diode in it.
This means you'll draw more current, and you should put a resistor in each of the parallel branches to compensate and balance the load.

Here is a wizard program to help design LED circuits: http://led.linear1.org/led.wiz It's pretty simple and self-explanatory but will show what value resistor to use and where to put it.
 
Last edited:

carmexx

Active Member
Hey Kodiak, thank you very much for the advice and the link.

As far as the info goes on the design of my LED i am wondering if I need just 1 resistor....or does it mean 3 resistors?

Solution 0: 3 x 1 array uses 3 LEDs exactly
+12V
+ -|>|- -|>|- -|>|- -/\/\/\- + R = 68 ohms
The wizard says: In solution 0:

* each 68 ohm resistor dissipates 42.5 mW
* the wizard thinks 1/4W resistors are fine for your application Help
* together, all resistors dissipate 42.5 mW
* together, the diodes dissipate 262.5 mW
* total power dissipated by the array is 305 mW
* the array draws current of 25 mA from the source.
 

KodiakBear

Active Member
one resistor can be connected to multiple LED's.
The important part is that whatever current passes through the LED's also passes through the resistor (which is why the resistor has to be in SERIES, not PARALLEL to the LED's). the idea is that as the LED's warm up, their resistance lowers, which would allow more current to pass. The series resistor will "feel" that rise in current and create a larger voltage drop, reducing the voltage available for the rest of the series branch, and effectively reducing the current in the LED back to what it should be.
Without the resistor the LED would just warm up and start passing more current than it's rated for. This means shorter life, and in most cases a shift in emmitted frequency (not such an issue for moonlights, but if you're wanting to make an LED array to supplement the PAR in your day-lights this could be a serious concern)
 

Brady92

Member
started this project last night just got all the parts together (had everything just laying around it was awesome) and layed the circuit out and then had to leave and finished it this morning and it works great and only invested around 30 mins in the entire process and i cant wait till tonight to see how it actually look
 
Top