Tutorial: Creating LED wiring harnesses for your builds.

[Duddly01]

 

I have had quite a few people ask me how I create my LED wiring harnesses for my builds so I decided to do a more in depth step by step of how I am creating the harness for my 1969 Cougar build.

Setting up my work space and all the tools and supplies laid out.

set the soldering iron to 250c

trimmed the battery compartment and soldering a small section of wire to the switch. The heat shrink and wire twisting to keep it clean.

I had created the trunk floor and trial fit with the chassis and body and drilled the hole for the switch. Now with the battery holder wired I glued it to the trunk floor panel. Then soldered the switch, taillight wiring and leads to front.

trial fit in chassis, test fit battery cover and glued in switch and wires to back of floor. I already glued the side glow fiber to to taillight LEDs so it will light up the length of the taillights.

twisted front leads to keep clean and test fit with chassis and interior. Dash was drilled earlier for gauges. Added side glow fiber optic for the gauge lights and cut interior tub and test fit.

drilled firewall for headlight leads and test fit. Soldered headlights, gauge lights to rear leads.

finished wiring harness, test fit to build components and check gauge lighting. Once the gauge faces are in I think it will look good.

now that’s it, easy peasy. Now get out there and light up your builds! ?

 

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[Ace-Garageguy]

Definitely some good info.

One thing to remember with any model lighting project is to use light-blocking material where appropriate, to prevent light "leaks".

It was somewhat challenging back in the days when all we had were incandescent bulbs that ran quite hot, but today with cool-running LEDs, aluminum foil works a treat...much better than silver or black paint.  

[Duddly01]

48 minutes ago, Ace-Garageguy said:

Definitely some good info.

One thing to remember with any model lighting project is to use light-blocking material where appropriate, to prevent light "leaks".

It was somewhat challenging back in the days when all we had were incandescent bulbs that ran quite hot, but today with cool-running LEDs, aluminum foil works a treat...much better than silver or black paint.  

Good point, I make an enclosure for the gauge lights and bare metal foil. I should have mentioned that. I have made the enclosure but I foil after paint. For where I plug into the headlights etc. I often use liquid electrical tape at time too.

Edited August 24, 2024 by Duddly01

[NOBLNG]

Cool ! What do you use for guage faces?

[Duddly01]

2 hours ago, NOBLNG said:

Cool ! What do you use for guage faces?

I just make clear lenses and apply printed decals of actual gauges

Edited August 25, 2024 by Duddly01

[iBorg]

An alternative source for LEDS is to look at DollarTree. They tend to have some dirt cheap LEDs with a battery holder at several holidays including Halloween. They may be in a plastic enclosure but I've broken them with a pair of pliers.

[peteski]

18 hours ago, iBorg said:

An alternative source for LEDS is to look at DollarTree. They tend to have some dirt cheap LEDs with a battery holder at several holidays including Halloween. They may be in a plastic enclosure but I've broken them with a pair of pliers.

With those, don't forget to use resistors in series with the LEDs. Even Design LEDs have the resistor installed next to each LED (in  heat shrink tubing).

[iBorg]

I've had success just cutting the wiring harness and using what's there but polarity must be right for it to work. I'd create the harness and twist the wires before even considering wiring it together.

 

[Duddly01]

1 hour ago, peteski said:

With those, don't forget to use resistors in series with the LEDs. Even Design LEDs have the resistor installed next to each LED (in  heat shrink tubing).

This is only necessary if greater than 3v. I haven’t tried to use dollar tree LEDs, but I do get many from Amazon but they are generally not as bright from what I have found. The big plus though is you can get packets of a whole bunch, with resistors prewired for quite cheap. The switches and battery cases the same. 

[Duddly01]

26 minutes ago, iBorg said:

I've had success just cutting the wiring harness and using what's there but polarity must be right for it to work. I'd create the harness and twist the wires before even considering wiring it together.

 

I am actually not sure what you are getting at. I use pretwisted wire much of the time. Only have to unravel a bit for heat shrink.

[peteski]

1 hour ago, Duddly01 said:

This is only necessary if greater than 3v. I haven’t tried to use dollar tree LEDs, but I do get many from Amazon but they are generally not as bright from what I have found. The big plus though is you can get packets of a whole bunch, with resistors prewired for quite cheap. The switches and battery cases the same. 

Well, some LEDs (of certain colors have lower forward voltage than others.  Without getting too technical, for example a red or yellow LED has a lower forward voltage and will "steal" all the current for for example a white or blue LEDs which have higher forward voltage. 

in your circuit a resistor shape appears to be visible under the heat shrink right next to the LED.  Do you cut those resistors off?

Edited August 26, 2024 by peteski

[Duddly01]

52 minutes ago, peteski said:

Well, some LEDs (of certain colors have lower forward voltage than others.  Without getting too technical, for example a red or yellow LED has a lower forward voltage and will "steal" all the current for for example a white or blue LEDs which have higher forward voltage. 

in your circuit a resistor shape appears to be visible under the heat shrink right next to the LED.  Do you cut those resistors off?

No, I do use resistors. I often use. 6v battery case, just not this build. And I stand corrected, my red ones always have resistors even when I don’t for the headlights.

[peteski]

3 hours ago, Duddly01 said:

No, I do use resistors. I often use. 6v battery case, just not this build. And I stand corrected, my red ones always have resistors even when I don’t for the headlights.

Now that makes sense (to someone who has been dealing with various LED-based  designs, not just for models for over 40 years).

 

Edited August 26, 2024 by peteski

[Duddly01]

10 hours ago, peteski said:

Now that makes sense (to someone who has been dealing with various LED-based  designs, not just for models for over 40 years).

 

Nice! Now that is taking it to the next level.

 

[peteski]

On 8/25/2024 at 7:35 PM, Duddly01 said:

This is only necessary if greater than 3v. I haven’t tried to use dollar tree LEDs, but I do get many from Amazon but they are generally not as bright from what I have found. The big plus though is you can get packets of a whole bunch, with resistors prewired for quite cheap. The switches and battery cases the same. 

Well, not in all instances.  When modelers use a source of 3V it is usually small button cell Lithium batter (like CR2032).  Those batteries are incapable of supplying current high enough to burn up most LEDs.  Without getting too technical, that is because those small batteries have high internal resistance.  That internal resistance acts in a way similar to an external series-connected resistor.

If your 3V source was capable of supplying high current (low internal resistance), you could easily overdrive white blue and especially red and yellow LEDs.  LEDs operate on current.  White, blue and true green LEDs at their normal operating current develop around 3V across them, while red LEDs develop 1.7V and yellow and yellow/green around 2V.  If you connect couple of AA or larger size alkaline batteries in series that will give you a source of 3.1V with with low internal resistance (they can supply large amount of current).  If you connected that to a white LED, without an additional series-connected resistor it would glow very brightly. If you connected It to a red LED, it would glow extremely bright for an instant, then it would go dark after releasing its "magic smoke".

Most modelers don't have any electronic background or understanding how LEDs operate and build their LED circuits based in anecdotal info find online or even in magazine articles (which are usually written by average modelers without full understanding how LEDs work).

[Katsusauce]

3v. batteries and swithches are on the chassis, and all 16 LED's are on the body. 

Everything is from Evans Designs. 

Edited April 6 by Katsusauce