Headlights/Tail lights - other power source

Hani79 · #1 11-22-2002, 02:40 PM

Hey everyone...I really want to add a few LEDs for headlights and taillights. But I got to thinkin', I don't want to have to switch them on or put a piece of paper between the new CR2032 battery. Shouldn't it be possible to take a lead from the wires running to the motor and attach them to the LEDs so that they would turn on every time the car is in motion? I know that this would result in a shorter run time, but I think it would be a great mod.

With that in mind, I opened my GT-R up and found a couple wires (blue and white) going to the motor. They ran to the board and attached to two points labeled "F" and "B". (Assuming Forward and Backward) If I am correct, those should be positive wires carrying the charge to the motor. I found the GND wire that attached to the board too. So assuming this would work, I touched the positive lead on the LED to the 'F' wire (positive) and the negative lead on the LED to the GND wire from the board. I then pressed forward on the control, but it didn't light up. (I tried the same for the backwards function.) So, it's not working as I thought it would. I'm not a electrition or anything, but shouldn't it have worked?Does anyone have any suggestions or ideas? Maybe someone more electrically inclined can try this out and let the rest of us know. Thanks!

john · #2 11-22-2002, 03:53 PM

If you use a watch battery or what have you and set up a standard LED set up (always on), then all you need to do is wire in a transistor to the PCB that senses when there is current going to the motor. If there is current, the transistor will open up the battery to LED circuit.

How's that for a solution?

#3 11-22-2002, 04:14 PM

u no what hani i tried the same thing with again no luck. i wonder what it is we are doing wrong?

Hani79 · #4 11-22-2002, 04:19 PM

John, that seems to be a FANTASTIC solution. But, I must admit that I am not to familiar with all the terminology. What kind of transistor? Do I solder it in? I am assuming the PCB is the circuit board, right? Where do I attach the transistor?

Any help is appreciated! You rock!

Hani79 · #5 11-22-2002, 04:25 PM

Bit Char Bloke, glad to see that I am not alone!

#6 11-22-2002, 04:27 PM

lol , well its wat i thought would work but obviously it dont :P

john · #7 11-22-2002, 04:32 PM

I'm no expert either

But there is a great little tutorial here that can teach you everything you need to know about LEDs, transistors and such.

That's where I got the idea to use a transistor in the first place! I haven't actually wired any LEDs yet. But I'll get there.

Hani79 · #8 11-22-2002, 04:43 PM

Thanks so much John! I'll let everyone know if I get this to work and I'll post pictures showing how I did it.

I'll cross my fingers and hope I don't kill my MicroSizer!

Gent · #9 11-23-2002, 02:28 PM

Guys,

Pleas ekeep us updated on the LED situation. I just got into this hobby with a el-cheapo clone (shen qi wei or something). I am trying to turn the car into a police car by adding blinking LED's for siren lights, and red LED's for tail lights. I picked up all the LEDs and batteries at Radio Shack, and it was simple enough to test them outside of the car, but installing them is another story. Any help with this tranistor idea, including pics and info on type and size, and were you purchased it would be great. Thanks.

P.S.
If you don't want to use the big CR2032 battery, Radio Shack sells a 3V lithium battery, the CR1216, that is thinner and about 1/4 the size, and it powers the LEDs just as well.

El Rojo · #10 12-04-2002, 12:28 AM

The reason the leds won't light on a stock bit is due to the fact that the pitiful 1.2V supplied by the single cell is insufficient to power most leds (which require a forward voltage in the 3-5V range). I'm going to try the mentioned transistor idea, I'll post results.

El Rojo

hbarer · #11 12-04-2002, 11:24 AM

i've had good results
running leds
off dual battery setups
1battery is not enough
but 2 works ok
solder 1 wire to the heatsink
and the other
to the wire that touches
the side of the motor
then you reverse the
polarity on 1 set of leds
so you have headlights going forward
and taillights in reverse
this isn't a very good picture
but you get the general idea

oink

Gent · #12 12-04-2002, 11:43 AM

hbarer,

So are you running the LEDs of off the car's battery, or is there a second small battery in there that we can't see on the picture? Also, what did you use to attach the lights to the car? Could you send a close up of that picture? Thanks.

El Rojo · #13 12-04-2002, 12:39 PM

hbarer,

That's a cool modification, I like the simplicity of your design. Reversing the polarity on the LEDs for brake lights is ingenious.

I'm still going to apply the transistor to mine as I do not want to perform the two-cell mod. I am going to use a 3v lithium button cell, and I'm wiring mine so that the contact points are on the chassis, so that body swaps can still be lit.

El Rojo

DarthRacer · #14 12-04-2002, 04:23 PM

Quote:

Originally posted by john
I'm no expert either But there is a great little tutorial here that can teach you everything you need to know about LEDs, transistors and such.

Great Link!
I tend to forget how all of that stuff works.
It is better that reading through all of my electrical theory books!!

mjb · #15 12-05-2002, 05:11 AM

Quote:

Originally posted by El Rojo
The reason the leds won't light on a stock bit is due to the fact that the pitiful 1.2V supplied by the single cell is insufficient to power most leds (which require a forward voltage in the 3-5V range). I'm going to try the mentioned transistor idea, I'll post results.

El Rojo

Depending on the LED, standard RED issue will get up at 1.8v. Greens and Yellows are higher, in the 2-3v range. White and Bue are higher still, usually 3.6v-4.0v for white, and 5.0v for blue. Check the manufacturers spec, and as usual, try it out and see.

Remember that although the cell is 1.2v, the RX chip needs a minimum of 2.2V to work. There is a charge converter on board the PCB, and there is (on my OEM bullet) 2.97v available here. This is below the minimum spec for a white LED, however, it lights fine (just not at the stated brightness).

There are some other mods which use this 2.97v supply, you can pick it up off one end of a diode on the board. Be careful not to draw too much current, the voltage will sag if you do!

This remains at 2.97v long after the car has stopped moving

If you're looking for the diode, on my car, it's a small, cylindrical glassy-orange item, one end has a dark stripe around it. It's right near the edge of the PCB to the FRONT of the car. The striped end is +2.97v, take ground (0v) from the pad on the PCB marked "0v/GND". White LED, no series resistors ... headlights!