T -435/ SM-42

Re: T -435/ SM-42

Postby ConducTTor » Mon Jul 12, 2010 6:43 pm

Hey Martin, the first question is, what voltage are the LEDs rated for?
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Re: T -435/ SM-42

Postby clipers » Mon Jul 12, 2010 6:53 pm

red 1.8-2.4 V
white 1.8-2.4 V
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Re: T -435/ SM-42

Postby CSD » Mon Jul 12, 2010 7:00 pm

Hey, man, looks great!

Second question: Are you planning on reversing headlights and are you running DC or DCC?
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Re: T -435/ SM-42

Postby ConducTTor » Mon Jul 12, 2010 8:28 pm

Oh yeah, a third question which is not crucial: how much current do the LEDs require?

You will need resistors in line with the LEDs. Here is the formula for figuring out the resistor value: R = (VS - VL) / I

Where R = resistance, VS = supply voltage, VL = LED voltage and, I = LED current.

What we know: VL = 1.8 - 2.4 volts. Lets play it safe and say 2 volts.
A few assumptions:
Your supply voltage is 14volts.
We now need the LED current. An average current required for a 2V LED is about .02A.

So, R = (14-2) / .02

This would give you a resistor value of 600 ohms.

That means you need to have resistor of at LEAST 600 ohms in line with each LED. You also need to know which terminal of the LED is + and -. Getting this wrong won't blow anything - your lights will just be reversed with direction of travel.
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Re: T -435/ SM-42

Postby clipers » Mon Jul 12, 2010 11:14 pm

Thanks Condukttor for all calculation. I am using the electronics from V100. However I want to remove this rectangle circuit board on the front and I am not sure what power supply is coming out over there. Is there still 12 V or less? Maybe CSD can help me because I know you are using V100 for your project. On the original board was one resistor for two leds (white) and one for the red.
I am running DC and I want to make reversing headlights.
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Re: T -435/ SM-42

Postby ConducTTor » Mon Jul 12, 2010 11:33 pm

clipers wrote:..... I want to remove this rectangle circuit board on the front and I am not sure what power supply is coming out over there......


You can put a multimeter set on DC voltage and check. CSD likely has done this a bunch of times though so he may be able to give a quick answer.
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Re: T -435/ SM-42

Postby CSD » Tue Jul 13, 2010 10:40 am

I assume you will be using the main circuit board and replacing the lighting circuit board with your custom lighting. The pins from left to right as per your drawing are 1. red, 2. common and 3. white. All are biased so that the common point is positive and the white or red is negative.
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Re: T -435/ SM-42

Postby scaro » Tue Jul 13, 2010 7:49 pm

What is the Tillig V100 wheelbase again? I think we discussed this and it was only 19 or 20mm ? (Can't find the old posting)

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Re: T -435/ SM-42

Postby clipers » Fri Jul 16, 2010 12:26 am

So far I was able gather more information regarding circuit boards. Couple things;
1. There is 12V on the both side
2. The smd led’s have to be connected in parallel
3. I used this calculator http://ledcalc.com/#calc to get correct resistors
According to my calculation for 3 smd led 0603 (1.8-2.4V, 20mA) in parallel with 12V supply I will need resistor of 220ohm. If I am mistaken please correct me before I make some damage.
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Re: T -435/ SM-42

Postby CSD » Sat Aug 07, 2010 11:24 am

clipers wrote:So far I was able gather more information regarding circuit boards. Couple things;
1. There is 12V on the both side
2. The smd led’s have to be connected in parallel
3. I used this calculator http://ledcalc.com/#calc to get correct resistors
According to my calculation for 3 smd led 0603 (1.8-2.4V, 20mA) in parallel with 12V supply I will need resistor of 220ohm. If I am mistaken please correct me before I make some damage.


Sorry for the late reply. the 220 ohm resistor should do it. I actually get 180ohm, but a little more won't hurt anything.
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