Thread: How-to add LED's & have them pulse from amplifier

I figured since not many people are aware of how to add LED's to their car it seems, I would give a stab at a how-to on how you can easily accomplish this task.

First off, the items, tools, and resources you will need to do this project.

Items:
-Project box (avail @ Radio Shack or alike for approx. $7) *optional, LEDs can be mounted somewhere on car or elsewhere
-Resistors, sizes will be spoke about (avail @ Radio Shack or alike for $0.99 per 5)
-LEDs - I used T1 3/4" (avail @ Radio Shack or alike for a range of $1-3.99/ea)
-LED mounts (for T1 3/4", there are plastic for $0.99/5 or metal $1/ea)
-Switch, if you'd like (avail @ Radio Shack or alike for $4-10 depending on style)
-Audio Wire or any (avail @ about anywhere that has audio stuff, Radio Shack, Walmart, Target, Best Buy, etc etc. Prices vary on gauge and amount)
-Shrink wrap (local autoparts store, unsure of pricing)

Tools:
-Screwdriver (for box if you got one)
-Soldering Iron & flux
-Needle-nose Pliers
-Drill & Drill bits
-Knife/Scissors
-Wire Cutters

Resources:
-http://ledcalc.com/ (for calculating resistor size needed)
-http://www.the12volt.com/ohm/ohmslawcalculators.asp (for calculating volts)


That is all that is needed to complete this project.
Now onto the project itself.

I will do a mock project using 6 T1 3/4" red LEDs, and connecting them to a 1k RMS watt amplifier.


Step 1:

Gather all of the materials.

Step 2:

Measure out your box or area that you are going to put your LEDs. Drill the holes in the designated spots for your mounts. While you are at it, drill the hole for wires that will be leaving the box, and if you have a switch, one for that as well. Now insert your holders into their designated holes.

Step 3:

Add your LEDs to the holes, and match up the leads. As a rule of thumb, the longer lead is usually positive. For a series, you want a positive lead, then the negative of the same LED connected to the next positive, then the neg to the next pos, etc.



Step 4:

Solder the leads together leaving the first positive and last negative free. Those will be dealt with soon.

Step 5:

Now you can insert your switch if you have one, or continue to the next step.

Step 6:

Now measure out the length of wire that you will need to accommodate the needs of your LED box, I made mine about 4 ft long that way it can be anywhere in the car at any time.

Step 7:

Now we figure in the resistor amounts and sizes.
A while earlier I said we were going base it off of a 1k watt amp with 185W per channel at 4 ohms (if you do not know the specifications of your amplifier it can be found on box, manual or online), if you go to http://www.the12volt.com/ohm/ohmslawcalculators.asp and plug it into the last equation on the page it shows approximately 27 volts max is being pulsed out of the amp.

Now that we know the max volts, we can go to http://ledcalc.com and plug that into that equation.

Our Supply Voltage is 27, Voltage drop because they are standard red is 1.7, LED current for the majority of all LEDs is 20 milliamps, and we are doing 6 LEDs.

Calculate and it tells us 840 ohms 1/2 wattage resistance. Those are the only two numbers you will need. Get as close to 840 without going beneath. It recommends a 1000 ohm resistor so either buy a 1k ohm or buy two 500 (can be in series, one resistor soldered directly to next, just so if you are not doing same equation it is easier on you)




This step on DO NOT forget to put on your shrink wrap!




Step 8:

Now that you have your correct resistors, solder them to the positive side of wire and either to the switch (as pulsing voltage to a switch is bad) or directly to the free positive lead of the first LED we left. Shrink wrap.

If you have a switch, connect the other end of the switch to the positive lead that is left free on the first LED.

Step 9:

Now connect your other wire to the negative lead of your series. Shrink wrap.

Step 10:

Push your wires out the hole carefully as to not break any solders.



Step 11:

Close up the box.

Step 12:

Connect it to one channel of the amplifier and turn the system on. Flip your switch if you have one. With no luck at all, and only skill, there will be your mobile light show.


If you have any other questions, feel free to contact me. I hope this helps someone out there, and be creative! LEDs have very many options as I have demonstrated in my car!

Looks awesome! Do you have any more pics? Or a video of it working?

Originally Posted by dpzelenak

thanks much help, but i got two questions,,,will it still work if you have a single channel amp?,,,and can you us a led strip(store bought) in stead of making a box to put them in?

Yes it will work with a single channel amp. The port can be used when powering it. I have a 2ch amp powering two subs, and I have it twisted in with the coupler on the sub.

And as for the LED strip, I am not to positive, I think it would be blown as most factory made are for 12v power source max. As the subs have varying (usually between 1-27v), it would most likely blow out the LEDs. Give it a try though! Take a look at the packaging and see what it says.

just an fyi this does not work with an led strip(or at least the ones i bought)..i think it could work if you could find the right ohms to put with it but i dont have the resoures for an R&D ..maybe i'll try again this spring sometime