I need to amplify my current.

[apkarian100]

Hi guys,

I have made a LED array that uses 5A, each side of my taillights, but car only puts out 2A per side like a normal light bulb needs. I need a transistor circuit or a MOSFET to get more current to my LED arrays. Any advice or help?

Thank You

 

[Diesel_Bomber]

I have to ask...............how do you replace incans with LED's...............and burn 150% MORE power? I can't help but think that unless you've seriously monkey'd up the design, your tail lights will probably be too bright to be safe/legal.

:buddies:

 

[lctorana]

+1 on that question

Plus, I have to ask - what the hell have you got installed in your wiring loom that would limit the current to only 2A anyway?

 

[LukeA]

I have to ask...............how do you replace incans with LED's...............and burn 150% MORE power? I can't help but think that unless you've seriously monkey'd up the design, your tail lights will probably be too bright to be safe/legal.

:buddies:

+1

 

[Greg G]

I think this is what he's working on. Tail lights for a Dodge Viper....a friend of mine.

124 Lumiled Superflux, probably driven at about 50ma when the brakes are applied. ~ 6.2 amps. I don't know what gauge wiring the car has.

I was hesitant to even post on this thread because I tried to talk to him on the Viper site about this project, but he was not very receptive at all to ideas. I do want to see my friend get a workable solution though. I'd hate to see his car burn down due to an electrical fire. The good news is that the battery is located in the rear of the car, so if he does need to use a relay/mosfet type rig the power leads from the battery to the lights would be short.

 

[georges80]

Um...

124 Red LEDs at 50mA does not NEED to be 6.2A.

Each Red LED likely has a Vf of around 2.5V. So you would wire 4 in series (for around 10V) and a resistor to limit the current from a fresh 14.4V battery - unless there is a more elaborate current limiting circuit in place PER string.

So, you then have 124/4 ~ 31 strings at 50mA each. That is around 1.5A total for the 31 parallel strings @ 50mA each.

Seems like a bit more reading about LEDs and series/parallel and current regulation is needed before building anything...

cheers,
george.

 

[Greg G]

I agree it doesn't have to be, or should be, 6.2 amps. I don't know how he has these wired. I based the 6.2 amps estimate on worst case scenario, and the fact that he posted he needs 5 amps per side to drive them. 5 amps *sounded* to me like he was planning to run them all in parallel. Likely he has them (or should have them) 3 to a string, which would be about 2 amps draw on the cars brake light circuit. That should be fine with the factory wiring harness. He had talked about regulating the current using an LM350 and a resistor, which would leave him with about 9 volts of useful voltage per string.

I honestly have no idea how he's actually going to wire these because he's so secretive about it.

 

[georges80]

Yep. Regardless, the OP has gone very quiet and unless more info is forthcoming this thread should be allowed to fall off the end of the screen

cheers,
george.

 

[Greg G]

I wish I could be indifferent, but *if* this is the project I think it is, it is going in my buddy's $50,00 Viper, so I prefer things get worked out.

 

[apkarian100]

This is about a different project. I'm using 272 LEDs to light up a Acura NSX:

 

[apkarian100]

Greg, the Viper project will be fine. I will be using a LM350 circuit coupled with a PWM on the Viper. Each taillight in the Viper will only draw 2.1A, 2.67V for each LED, 50mA, 124 LEDs.

As far as the NSX goes, I am going to tap into the battery for additional power, being that each brake/parking light needs 4.5A per side. I am now using Sharp regulators coupled with PWM where the sharp reg is activated by the brake/parking signals, and the power is coming from a fused connection to the battery.

If you want to know why I am just replying, well, I have been trying to find the best solution on my own, calling up companies, and throwing questions at every forum I can think of.

I just wanted your help, was that too much to ask.

Thanks for any input you guys put in............................

I wish I could be indifferent, but *if* this is the project I think it is, it is going in my buddy's $50,00 Viper, so I prefer things get worked out.

 

[Greg G]

I thought you had already done the R&D on those and had done several?

 

[apkarian100]

I never said that, if you look on Viper Alley, it says "I have also started on the Acura NSX". So I went to test them yesterday on a vehicle and there are some things I need to tweak. It's one thing when you sit down and develope a plan and test it in your shop, it's another thing when you test it on the actual car.

BTW: I will be testing the Viper lights on a working Viper before they start getting sent out.

I thought you had already done the R&D on those and had done several?

 

[Greg G]

I just wanted your help, was that too much to ask.

Great attitude............

 

[LukeA]

These will be dangerous because of the intensity.

 

[Greg G]

They will be pretty bright. I don't know if there are any laws regulating it, but I would try to observe them. 272 LED's........wow.

I don't know if there are many guys here that have ever done this. We're mostly into portable LED's or home stuff.

A good place to ask this question would be allaboutcircuits.com. There are some sharp guys there on things like this.

 

[apkarian100]

Okay, sorry, I will try that other forum you said.

Yah, this guy with the NSX wants the brightest setup I can, he does not care about DOT regulations.

Thanks for the help Greg, didn't mean to scare you about the Viper project.

They will be pretty bright. I don't know if there are any laws regulating it, but I would try to observe them. 272 LED's........wow.

I don't know if there are many guys here that have ever done this. We're mostly into portable LED's or home stuff.

A good place to ask this question would be allaboutcircuits.com. There are some sharp guys there on things like this.

 

[Greg G]

There are definitely guys here that can answer your question, it's just a matter of them seeing this thread though.

I wish I knew the best way to do this, but I don't. Looking forward to hearing what some of the pro's think.

Post your question in the Projects Forum at allaboutcircuits and you'll have several answers in a couple of hours I bet.

 

[georges80]

You asked about amplifying current. The real issue is you need higher current supply to your array than specified for the original incandescents - so wiring and current capacity of the wiring is more the issue here - not 'amplifying' the current.

I guess the key point is that your original post about amplifying the current was a little bizarre since it's not the terminology that most folk would be using to frame the question.

Feeding power directly from the battery with thicker gauge wiring and then using the original brake signal to switch the LEDs on/off seems a reasonable way to go - which is what you outlined as something you're likely to do. Again, it is wire gauge (and fusing at/near the battery) that is important.

Sounds like all you need is a fuse to the Battery+, thick wire run down to the LED brake light. A power transisitor or preferably an automotive grade P channel FET to switch the battery+ side of the LED array. Wire the gate to a resistor to the same battery+ (to ensure the FET is normally off) and then wire another resistor to the gate. The other end of the 2nd resistor goes to your brake pedal 'signal' at the back of the vehicle - since likely the original brake light has permanent +12V to one side of the brake bulb and the other side is switch to ground through the switch on the brake pedal.



Or you could just use a relay instead of the power transistor or FET since it is only switching when the pedal is pressed - not like a high duty cycle etc. That is more likely what I'd choose if needing to provide a higher current rated feed to an aux brake light.

For the relay you would just wire one side of the coil to Battery+ and the other side of the coil to the original ground side of the brake light (that will be grounded when the brake pedal is pressed). Then take the contact side of the relay and wire one side of the NO relay contact to Battery+ and the other side to your LED array +ve. Wire the LED array -ve to the body.

Or if you want to be like the original vehicle scheme: wire Battery+ to your +ve on the LED array. Wire the Ground side of your LED array to one side of the NO relay contact. Wire the other side of the NO relay contact to Ground.

cheers,
george.

 

[apkarian100]

Again, I apologize for the incorrect title phrasing.

I like the relay method, but someone suggested another idea also. Tell me what you think:

So I needed to regulate the voltage anyways, I have seen a couple people use Sharp PQ09RD21 regulators to regulate the voltage and also to relay power to an LED array. The nice thing about this reg is that is has a built in on/off switch so I could place the input wire of the brake/parking lights on the switch to allow power to come from the battery via a fused connection. So it is a relay, but a Voltage reg also. The only thing is that they are 2A max, so this guy I talked to suggested placed sharp reg at each LED segment that consumes 1A, just to be safe.