LED lighting in paper models - How To?

[peter taft]

Originally Posted by scarmig

LOL.... yeah, I figured out the easiest way was just get a matching resistor for each LED and wire them 1 to 1. I'll probably take some time this weekend and get a bulk pack of LED's.

Hmmm..... wait a minute. I wonder if I could repurpose one of those cheap solar garden LED's. Just have to wire in a hard switch, and then it already has the circuit for the light sensor, the resistors and a hard board with a battery pack in place.

Now you are cooking with gas.....

[B-Manic]

This link was posted in BOMARC's PBJ build but I thought it appropriate to include it here as well. This site sells dynanic effect kits (light, sound & motion) kits for models.

Dynamic Scale Modeling

[DJStratoArt]

Originally Posted by B-Manic

This link was posted in BOMARC's PBJ build but I thought it appropriate to include it here as well. This site sells dynanic effect kits (light, sound & motion) kits for models.

Dynamic Scale Modeling

Oh wow, I've been looking for that link for ages!! Thanks for that.

[Getter 1]

One thing you will want to pay attention to is whereever the LED is you may want to black out the interior and isolate with say a black construction paper compartment to prevent light bleeding into un-wanted areas.

G1

[peter taft]

Originally Posted by Getter 1

One thing you will want to pay attention to is whereever the LED is you may want to black out the interior and isolate with say a black construction paper compartment to prevent light bleeding into un-wanted areas.

G1

This is a great idea, and one area easy to overlook - once it's all built and you switch on only to find light sparkling out of everywhere you don't want would be very annoying to say the least - Good reminder GETTER 1

[scarmig]

Okay, so I've cannibalized an LED solar light for the LED/resistor/battery in it. I added a mercury tilt-switch, so that the light comes on when the model is lifted from it's stand (that's the idea anyway).

How are you guys attaching the fibre optic strands to the paper where they need to shine? Superglue?

[scarmig]

Well I tried superglueing the ends of the fibre optics to the windows where I want the light to shine. That doesn't work. They pull off too easily. So I've gone with a "socket". Basically a tiny tube of paper rolled up as tight as I can and glued closed. I'm cutting this into small tubes about 1/3 cm and gluing them inside the model where I want the lights to shine. I'll then stick the fiber optic strand into the socket, and glue it at the top of the socket to hold it in place. I've done one, and it has held up over a week of being moved back and forth while work interrupts everything, so I think this will be okay.

[Jim Nunn]

Another source for LEDs, small switches, battery holders is All Electronics they take small orders and shipping is not that expensive.

Some thoughts, for a switch consider a reed switch you can hide it in the model and to operate the switch just bring a magnet close to the switch. The magnet does not have to be in contact with the switch.
Power source, I have considered using a coil of wire in the model with a bridge rectifier and small electrolytic capacitor to filter the DC. Without the filter the LEDs will pulse at 120 Hz and some people are sensitive to the pulsing. Then mount a coil outside the model hidden in the display base and powering this coil from a small 24 volt AC power source.
What you are making is a transformer with the primary coil outside the model and the secondary coil in the model. The magnetic field generated by the primary coil induces a current in the secondary coil in the model so no wires needed and no batteries required. Some issues, this would be a very inefficient transformer being an air core transformer but all you need to power the system and the LEDs is a minimum of 2.5 Volts DC and 20 to 50 ma per LED. Use Peters formula to calculate the resisters for the LEDs

Getting the transformer right would be tough part and would require some experimentation. I would start by winding the primary on a ½ in bolt or rod using 20 to 40 turns per volt. The secondary I would start with 10 turns per volt. The voltage I am referencing is the AC voltage feeding the primary coil. Use magnet wire for the coils.

And yes I am a certifiable Geek

Jim Nunn

[bagpiper]

Originally Posted by Jim Nunn

Another source for LEDs, small switches, battery holders is All Electronics they take small orders and shipping is not that expensive.

Some thoughts, for a switch consider a reed switch you can hide it in the model and to operate the switch just bring a magnet close to the switch. The magnet does not have to be in contact with the switch.
Power source, I have considered using a coil of wire in the model with a bridge rectifier and small electrolytic capacitor to filter the DC. Without the filter the LEDs will pulse at 120 Hz and some people are sensitive to the pulsing. Then mount a coil outside the model hidden in the display base and powering this coil from a small 24 volt AC power source.
What you are making is a transformer with the primary coil outside the model and the secondary coil in the model. The magnetic field generated by the primary coil induces a current in the secondary coil in the model so no wires needed and no batteries required. Some issues, this would be a very inefficient transformer being an air core transformer but all you need to power the system and the LEDs is a minimum of 2.5 Volts DC and 20 to 50 ma per LED. Use Peters formula to calculate the resisters for the LEDs

Getting the transformer right would be tough part and would require some experimentation. I would start by winding the primary on a ½ in bolt or rod using 20 to 40 turns per volt. The secondary I would start with 10 turns per volt. The voltage I am referencing is the AC voltage feeding the primary coil. Use magnet wire for the coils.

And yes I am a certifiable Geek

Jim Nunn

Nice one Jim. And without wanting to steal Jim's thunder, please note that Jim has indicated an AC to AC power supply. It will not work if you have an AC to DC power source (walwart). I am sure most spotted that but just wanted to emphasise that point. DC will not cause a transfer of energy across the coils.

Anyhoo thanks for sharing this idea mate. I look forward to seeing this in use. There are a lot of formula in regards to power transfer but experiment, as Jim says is much more fun.

Nice addition to this thread Jim.

Cheers
Jim