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I built my own homemade full wave bridge rectifier module for my LED tail since I realized that it was only half brightness due to AC. Well, doing a little more homework, I found out that it won't work installing it at the taillight itself. Due to circuit design, the brakelight will be on with the taillight due to backfeeding voltage. So, I thought of starting with the source. Can I just put a single rectifier at the start, near the lighting coil, or after the regulator so all sled lighting is getting 12VDC instead of AC? My taillight will work properly if I can do this. Thanks!
 

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What type of LED taillight are you using? I have a couple different aftermarket LED assemblies that work fine off AC. I just picked up an 09 crossfire one that I hope works off AC voltage too. I find the 1157 style individual bulbs don't work well. They only get about half the voltage they need so they are dim.

I was just discussing with a co worker today. Using an oscilloscope he found that off the shelf diodes don't work well at the frequency of the AC voltage the sled puts out. You may find rectifying the entire sled won't work all that well unless you have right diodes.
 

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[attachment=138984:DSC00556.JPG][attachment=138983:DSC00558.JPG]
[attachment=138976:DSC00518.JPG][attachment=138975:DSC00529.JPG]
[attachment=138974:DSC00532.JPG][attachment=138973:DSC00537.JPG]

i put some leds on sleds i got them on my f7 ,f6 and a zr 900 and a ski dont Cat happy they work just fine.
 

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hmm the LED tail strip I have on my bumper/lift bar puts out the same amount of brightness as it did when I tested it on a car battery. I'm not sure I understand how something that uses less power than a smoke detector can be effected so greatly by ac or dc...
 

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<div class='quotetop'>QUOTE (rotaryboots @ Nov 11 2009, 11:52 PM) <{POST_SNAPBACK}></div>
hmm the LED tail strip I have on my bumper/lift bar puts out the same amount of brightness as it did when I tested it on a car battery. I'm not sure I understand how something that uses less power than a smoke detector can be effected so greatly by ac or dc...[/b]
LED's are electronic devices and only light up when current flows in the correct direction. AC voltage cycles positive and negative and LED's won't work with that.
 

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Discussion Starter #8
Okay, so electronics gurus and anyone alike, check out my crappy drawing. Here's my little module. I thought I looked it over carefully enough, but I figured out after the brakelight stayed on with the taillight that I screwed up. The brake circuit is getting fed by the common. How can I fix this or make it work? I was thinking about adding a transistor on the light side of the brake circuit, that gets turned on by the brake power.
 

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Have you tried getting rid of the rectifier and going directly to the AC supply voltage? What taillight are you using? Many of us run ours off AC voltage just fine.
 

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<div class='quotetop'>QUOTE (carkhz316 @ Nov 13 2009, 12:40 AM) <{POST_SNAPBACK}></div>
Okay, so electronics gurus and anyone alike, check out my crappy drawing. Here's my little module. I thought I looked it over carefully enough, but I figured out after the brakelight stayed on with the taillight that I screwed up. The brake circuit is getting fed by the common. How can I fix this or make it work? I was thinking about adding a transistor on the light side of the brake circuit, that gets turned on by the brake power.[/b]
This should work properly, I hope it does as this is the next project on my list so Kev will stop running into me and blaming my dim light :p

Any chance you have the brake lever locked on?

Is there any AC voltage present between red/brown? If there is you need to find out why, this would suggest that the brake light would be on when connected normally
 

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Discussion Starter #11
My brake switch is still working as it should. I only get 12VAC on the red brake wire when the brake is applied. I can tell a slight difference when I hit the brake as well, but not much to be that noticeable. Here's the reason I wanted to wire it like this: If any of you have just stuck in a regular trailer LED light or equivalent that you can just buy at the auto parts store, it's designed to be run on 12V DC. When you wire it to the sled's AC, it will work just fine (as mine did when I had it wired the first time.) The downside is that due to the LED's being a diode, they are a one-way valve to electricity. They will only work when voltage is applied in one polarity. When AC is connected, it will only receive the positive half of the sine wave, thereby essentially receiving a pulsed 6V signal. With the bridge rectifiers connected, it turns it into a 12V DC source instead of AC, thereby giving the LEDs the full 12V they're designed to run on. It doesn't hurt to run them on 6V, it's just that they're not going to be as bright as they potentially could. I think I figured out why the XFire lights work well, is that they design them to be run on 6V instead of 12V, making them just as bright as my el-cheapo trailer light on 12V. My wiring homework mistake is that the brakelight circuit is getting a 6V pulse from the Common (brown) wire. But with a simple transistor on the brake circuit of the light, I'm pretty sure I could make it work. Otherwise, I might just say F*** it all and just do a XFire light.
 

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Not sure why this is not working as designed but perhaps you are running into the same issues that I am with the DC converter for HID.
The frequency of the AC from the stator plays havoc on standard rectifiers in that the diode junctions can not switch fast enough to keep up with the incoming waveform. You may need to build a bridge out of Schottky's - NTE 586 should do.
Using a transistor trigger is a good idea but I think you may run it the same issue with false triggers if you try to feed the gate with DC and a flashing light if triggered off of the AC (75HZ at 1500 RPM).
 

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Bad news, it is as I suspected. Look at the modified diagram. The bottom diode is not turning off fast enough which allows the top portion of the tail light AC wave to pass backwards through it. This wave travels along the black wire through the diode to the red wire and is visible as a 4VAC source on the brake input.
To fix this you need faster diodes but that introduces a new problem in that the voltage on the taillight when properly rectified with 13 VAC is will be in the 16.5 V range so you may need to clamp that down to 13VDC or risk popping the taillight.
Best option at this point is to get an LED light made for AC. What they do on these is use the proper resistors to have bright LED's with only half the wave

[attachment=139192:brakelight_1_.jpg]
 

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Here's the crossfire light. Looks better then the oval (truck style) one I ran last year.

[attachment=139220:100_2823.JPG]

[attachment=139222:100_2825.JPG]
 

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Discussion Starter #18
woot. Got it to work. It seems to be as bright as hooking it up to straight 12VDC. I haven't double checked the actual voltage output, but it should be system voltage, minus the voltage loss through the retifiers (which is like ~1V). All I did was add a power MOSFET (which I don't know very much about, but enough to understand the application and what it supposed to do.) to function sorta like a relay for the brake circuit, and a 500ohm resistor on the gate control. If it doesn't yield the output I want, or fries anything, I'll just resort to a Crossfire taillight. Here is the diagram. Feel free to comment/ input.
 

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I just e-mailed a pic of the wiring diagram to an elect eng. buddy and here is what he said:

Yes this could work but you do not need the FET (Field Effect Transistor). Remove it, it is the round device with the red wires attached to it along with the 500 ohm resistor. Simply connect the D (Drain) wire to the S (Source) wire.

Auggie
 
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