Jump to content
Model Cars Magazine Forum

LEDs in Model Car HELP


Recommended Posts

Hello everyone! So i have been wanting to put leds in my model cars and i have done this before. BUT i have done 2 circuits (yes 2 batteries 2 switches) . I have done this because i was using 2 3mm white LEDS in the front and 2 3mm red LEDS in the back. When i hook them up in a series and parallel circuit and the red LEDS are the only ones that work. The white ones just shut off why does it do this? It would be very nice if someone could make me a wiring diagram for this list.

2 - 5mm red LEDS

2 - 3mm yellow LEDS

2 - 5mm white LEDS

1 - 3mm yellow LED

 

78491.jpg

102_1.jpg

Link to comment
Share on other sites

Hello everyone! So i have been wanting to put leds in my model cars and i have done this before. BUT i have done 2 circuits (yes 2 batteries 2 switches) . I have done this because i was using 2 3mm white LEDS in the front and 2 3mm red LEDS in the back. When i hook them up in a series and parallel circuit and the red LEDS are the only ones that work. The white ones just shut off why does it do this? 

 

I'd really have to see your circuit to understand what YOU mean by "a series and parallel circuit".

If you hook all the lights together in simple parallel, IF they all draw the same amount of current, they will all shine equally brightly.

If some go out and some shine, the ones shining will most likely need to have resistors added to make the others come on.

And again, without seeing your existing wiring and knowing the exact specs on your LEDs. that's about all anyone can tell you.

Google "circuits for LEDs in models" for all the info you could possibly need.

Here's a place to start.

Link to comment
Share on other sites

I'd really have to see your circuit to understand what YOU mean by "a series and parallel circuit".

If you hook all the lights together in simple parallel, IF they all draw the same amount of current, they will all shine equally brightly.

If some go out and some shine, the ones shining will most likely need to have resistors added to make the others come on.

And again, without seeing your existing wiring and knowing the exact specs on your LEDs. that's about all anyone can tell you.

Google "circuits for LEDs in models" for all the info you could possibly need.

Here's a place to start.

The yellows and reds are the ones that work ALL the time, i could have a white or blue hooked to the battery then hok up a yellow or red then the yellow or red works and the blue or white shuts off. Im using a 3v battery on 3v LEDS

Link to comment
Share on other sites

The yellows and reds are the ones that work ALL the time, i could have a white or blue hooked to the battery then hok up a yellow or red then the yellow or red works and the blue or white shuts off. Im using a 3v battery on 3v LEDS

Well, no matter if they are all "3v" LEDs, they obviously don't all draw the same current. Right?

If they DID all draw the same current, they'd ALL be evenly illuminated when you wire ALL of them in parallel...right?

Do you know anything at all about electricity? Do you know what "current draw" means? Do you understand resistance in a circuit, and how you use it to balance various loads?

Do you understand what a parallel circuit is? A series circuit? Series / parallel?

Did you watch the video, or is that too elementary for you?

Maybe try reading this.  http://www.theledlight.com/LED101.html

EVERYTHING you need to know is there, there's a simple and logical reason why your LEDs act as they do, and YOU need to figure it out.

I don't mean to seem harsh, but there's no magic to this, there are WAY too many possible combinations of LED specs and wiring for anyone to be able to tell you exactly what to do, and I'm not there, I have no test equipment hooked up to your circuit, and I don't have the data on your LEDs.

Designing an LED circuit for a model is about the easiest thing you can do in electronics, and I've pointed you to all the information you need to get going in the direction so YOU can understand what you have and how to make it work.

Good luck.  :D

Edited by Ace-Garageguy
Link to comment
Share on other sites

Well, no matter if they are all "3v" LEDs, they obviously don't all draw the same current. Right?

If they DID all draw the same current, they'd ALL be evenly illuminated when you wire ALL of them in parallel...right?

Do you know anything at all about electricity? Do you know what "current draw" means? Do you understand resistance in a circuit, and how you use it to balance various loads?

Do you understand what a parallel circuit is? A series circuit? Series / parallel?

Did you watch the video, or is that too elementary for you?

Maybe try reading this.  http://www.theledlight.com/LED101.html

EVERYTHING you need to know is there, there's a simple and logical reason why your LEDs act as they do, and YOU need to figure it out.

I'm not there, I have no test equipment hooked up to your circuit, and I don't have the data on your LEDs.

Designing an LED circuit for a model is about the easiest thing you can do in electronics, and I've pointed you to all the information you need to get going in the direction so YOU can understand what you have and how to make it work.

Good luck.  :D

dude im like 14, i do other things than play video game like other people my age.Il read up on that. Thanks

Link to comment
Share on other sites

Do you have the polarities right? The negative side is the shorter lead. To wire in parallel all negatives should be tied together and all positives should be tied together. Your 3V source has to be able to supply enough current to supply all the parallel circuits. If you wire in series by wiring each led's positive to the next ones negative which would be series you would need a 21 volt supply because you would drop 3V across each led. An led will not get brighter or darker with voltage changes. It will either turn on or off.

Edited by 935k3
Link to comment
Share on other sites

you can reduce how fast the batteries run down by using smaller LEDs.

the larger LEDs you have listed put out more lumens but they will also run the battery down faster.

you can put very small LEDs behind the currently installed lenses.

try researching surface mount LEDs.

Link to comment
Share on other sites

Do you have the polarities right? The negative side is the shorter lead. To wire in parallel all negatives should be tied together and all positives should be tied together. Your 3V source has to be able to supply enough current to supply all the parallel circuits. If you wire in series by wiring each led's positive to the next ones negative which would be series you would need a 21 volt supply because you would drop 3V across each led. An led will not get brighter or darker with voltage changes. It will either turn on or off.

so it sounds like i need to move to 9v and get some resistors?  I was thinking of picking these up and maybe doing a police car.

http://www.modeltrainsoftware.com/dcflasher.html#_ga=1.94039390.2145493355.1476926055

Link to comment
Share on other sites

Do you have the polarities right? The negative side is the shorter lead. NOT ALWAYS. I HAVE MULTIPLE LEDS IN STOCK HERE THAT HAVE THE SAME LENGTH LEADS. To wire in parallel all negatives should be tied together and all positives should be tied together. Your 3V source has to be able to supply enough current to supply all the parallel circuits. If you wire in series by wiring each led's positive to the next ones negative which would be series you would need a 21 volt supply because you would drop 3V across each led. An led will not get brighter or darker with voltage changes. It will either turn on or off. ALSO NOT ALWAYS. MANY 1157-REPLACEMENT BULBS, FOR INSTANCE, DELIVER TWO DISTINCT LEVELS OF LIGHT BY INCORPORATING RESISTANCES IN THE CIRCUITS DRIVING THE EMITTERS.

 

Edited by Ace-Garageguy
Link to comment
Share on other sites

so it sounds like i need to move to 9v and get some resistors?  I was thinking of picking these up and maybe doing a police car.

http://www.modeltrainsoftware.com/dcflasher.html#_ga=1.94039390.2145493355.1476926055

You need to understand how the things work and do the math, not just randomly start putting bigger batteries in the circuit.

I noted in my first response you're probably going to need resistors to balance the loads of the LEDs that stay ON with the ones that go OFF.

There's math required to get the RIGHT resistors. There's thinking involved. It's not hard, but you need to do it.

Link to comment
Share on other sites

dude im like 14, i do other things than play video game like other people my age.Il read up on that. Thanks

Excellent. This is a great opportunity for you to get a little self-education in basic electronics. You might find you like it. I did at about your age, and it's helped me in my career my entire life.:D 

Link to comment
Share on other sites

Excellent. This is a great opportunity for you to get a little self-education in basic electronics. You might find you like it. I did at about your age, and it's helped me in my career my entire life.:D 

I found it out now the LEDS i was looking at for a police car have resistors soldered into it. This makes it work on a 9v battery and balances out the red only working. I'm slowly getting this figured out!

Link to comment
Share on other sites

Well this one is done, i like it and lots i will do different next, i will keep uploading stuff and questions on this thread too.

Looks great. Nice work. 

Aluminum foil can be used to keep the light from shining out of places you don't want it, like around the hood and the hood vents.

Because LEDS produce very little waste heat, you can usually wrap an LED with foil to control light leakage.

Link to comment
Share on other sites

Bill's suggestion about aluminum foil is right on (and something I had suggested to another of the builders here).

Since aluminum foil can sometimes be difficult to glue to things, Bare Metal Foil might be easier to wrap around LED's to control light "leakage".

In some instances, having the LED inserted to metal tubing can also be great as a bezel and to control light "leakage".

Link to comment
Share on other sites

Are the LEDs you used dimmable? If so and just for giggles, add a resistor in series with the headlights and a switch that will bypass (short out) the resistor; this will give you headlights with high/low beams, depending on whether the switch is in the open or closed position.

In a similar fashion, a resistor/switch combo can be used to provide tail lights and brake lights.

Edited by BigTallDad
Link to comment
Share on other sites

Can we see a diagram after this is figured out?

Image result for led model parallel circuit

One of the simplest circuits imaginable. The resistors are the brown blobs. The VALUES of the resistors are worked out using the specs of the LEDs, or experimentally on a breadboard.

READ THIS:   http://www.evilmadscientist.com/2012/resistors-for-leds/       (be patient...the site is slow to load)

Link to comment
Share on other sites

Looks great. Nice work. 

Aluminum foil can be used to keep the light from shining out of places you don't want it, like around the hood and the hood vents.

Because LEDS produce very little waste heat, you can usually wrap an LED with foil to control light leakage.

i did use some foil, not enough tho. Iv never done this so next car will be better, i just ordered a 1/18 motormax police car and police leds, i will post that here also.

Link to comment
Share on other sites

  • 2 weeks later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...