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LED turn signal chaser mod/question

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Sockles

New Member
Hey guys, im working on replacing my mini bikes turn signals with LED that act like sweepers/chasers and had a few questions. First I've attached the general picture of what I have in mind. I already got the coding done and all that.
What I've been wondering is, since the microcontroller needs (I think) around 5V I would put a voltage regulator in between the battery and the microcontroller. Correct?

Now, for the LEDs I've got eight LED's per turn signal. They are wired up in series, 3,3,2. for resistors i've got 330ohm(3 LED's) and 470ohm(2 LED's) as you can see on the picture.
But now I was basing off of having a steady 12V sourcing the leds, meaning I would need some amp or capacitor.

I am a newbie, so bare with me. hope I didnt miss anything

8814-ScreenShot042.jpg
 

audioguru

Well-Known Member
Most Helpful Member
1) Connect a 1k resistor to each output from the micro-controller.
2) Connect the base of a little NPN transistor (2n3904 in north America, BC547 in Europe) to the resistor, its emitter to 0V and its collector to the rersistors feeding the cathodes of the LEDs.
3) Connect the anode of the LEDs to +12V. The logic must go high to turn on a transistor which turns on its group of LEDs.
 
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audioguru

Well-Known Member
Most Helpful Member
Thanks for your help! So I'm reversing the polarity through the microcontroller?
I don't know which polarity you have now. Just make the outputs of the micro-controller go high to turn on the transistors which turn on the LEDs.
 

MrDEB

Well-Known Member
don't forget a regulator

the PIC is only 5v, the battery is 12
I think a LDO voltage regulator is what you want so you don't build up alot of heat in the regulator.
I might be wrong?? but you do need a voltage regulator.
 

audioguru

Well-Known Member
Most Helpful Member
the PIC is only 5v, the battery is 12
I think a LDO voltage regulator is what you want so you don't build up alot of heat in the regulator.
I might be wrong?? but you do need a voltage regulator.
A LDO regulator heats exactly the same amount as an ordinary regulator. The heat is caused by the voltage across it (input voltage minus output voltage that cannot be changed) times the current (that cannot be changed).
He already has a 5V regulator.

He wanted to convert the 5V output of the PIC to drive LEDs from 12V.
I suggested using NPN transistors.
 

audioguru

Well-Known Member
Most Helpful Member
I thought he was refering to a regulator for the PIC
Yes.
He already has a 5V regulator for the PIC. It draws a very small current so the regulator will not get warm.
A LDO regulator also will dissipate exactly the same amount of heat.
 
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