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Trying to make an LED Map, so placing an led anywhere on the map will make it light, any help? Answered

I'm trying to make a map so that I can place an LED anywhere through it and it'll light up. Kind of like the old push pin method only the push pin is a single LED and I can place as many as I want on the map wherever it may be and it'll light up. I found one online but it's very expensive so I was trying to see if I can build one. The only thing I can find online that would help would be conductive foam but I don't know what to do with it, my guess would be to connect a ground pin and a positive pin into the foam, wire those up to a plug, plug it into the wall and the foam would send power anywhere leaving me to place the led through the map and into the foam and having the led light up. Here's a link to what I found online and I'd like to recreate it. Can anyone tell me how please?



3 years ago

That would be a particularly challenging task. Something along the lines of inductive coupling might work:

capacitive coupling would not be bad either, circuitry would be a bit different:

I made this video showing off some stuff around my slayer exciter, which is like a solid state tesla coil. With the correct arvomiko plug on the end of the LEDs, you could make them light up when in the range of the exciter, which could be close to the map, so that the LEDs light up when they are close or on the map. You will, however, need some form of a ground connection and antenna to pick up the EMF fields the exciter emanates. (note this method will cause LOADs of EMI and interference, jam up phones, touch screens, radio, etc. I have a comprehensive 'able on this SEC circuit too.)

(Also, you can probably use microwaves to energise certain circuits, although that is obviously dangerous, or you could use UV blacklight shining onto the map externally, or back projection, and use fluorescent dyes like highlighter markings in substitute for LEDs. )


3 years ago

Well when in doubt, just use a potato!


3 years ago

I'm assuming no one is going to make a scaled model. :(

Conductive foam is not something that people just have lying around and, at least personally, if someone is going to invest in buying some foam they're just going to build the whole map, not just a demo.

What are planning on using it for? Depending on the use there may be easier ways to build it.

Maybe it would be easier to make pins for the LED's.

Something like a headphone jack, just thin and pointy.

This was it is more stable, only makes one hole and the resistor can be placed inside the pin.
Was thinking of these thin brass tubes for model making, a plastic sleeve for insulation and a pointy pin going all the way through.

The resistor inside the tube, connected to the pin would also make sure the pin makes no short inside the tube.

If the diameters are small and matching enough the use of a fine wire mesh instead of foam might be possible, eliminating the resistance problem of the foam.

For bigger wires I would use spring loaded wires with a distance shorter than the diameter of the pin.

Can try my bad drawing skills and make a pic if it helps to understand.

Thanks for taking the time to draw this. Per my last comment, I know I'm asking for a lot but would it be possible to make an instrucable on just a single led such as your picture listing the materials you used. That way I can scale up and make it work. It would be so appreciated!

Not for some time, I'm afraid, I'm quite tied up with other projects and proper work right now.

I'm still working on it, whenever you have a chance will be ideal. Thank you so much for your help.

I knew you can do better drawings than me ;)
Yeah, like that, just with nice angles where the material comes together and a pointy bit at the tip to make penetration easier.
But I really think for something that is meant to placed and moved a lot it is the best option.

Your ideas got me inspired to continue. I feel as though I can make this, however if you read the comment above I would so highly appreciate a scaled actual model such as the image illustrated above.


3 years ago

I wasn't expecting this many people to reply so quickly. All the answers have been helpful enough to get me more into thinking it can be done. Although the terms used are still foreign to me. The method I've seen with it doesn't require a tube inbetween. Basically oust puncture an led through. I don't know if it's too much to ask for but can anyone make a model using just one LED and I can work with that? Displaying what the parts were and how it was done. A secondary question would be, how do I get a current to go through the foam. Is my pin idea correct in that I wrap parts of a 9v wire around pins that have been stuffed into foam and then plug the wire into an outlet?

I'm sure with a scale and these questions answered I can start on the map and be more than happy to make an instruct able. By the way, stay tuned for my entire pc build, lighting and room renovation instructable.

you could get a bread board and put the map over it

Yes you can do so but not with directly the led. You can use electromagnetic induction. There will be a big electromagnetic coil made of copper wire under the map covering the whole area. And then you can make a setup of led like a board game piece which will also contain a small electromagnet (SEE IMAGE). Thus when you will put the led piece over the map it will light up due to electromagnetic induction. Sorry for the rough drawing. drawn in a hurry. When u make it plz post its image. kindly follow me.


Just an led? Probably not. However, with an appropriate inductive pickup, embedded into the movable light module, one could use the same basic technology as used by inductive cell phone chargers to deliver power to the light without a direct contact connection.

In my opinion, the primary challenge will be in making a map-sized inductive charging mat, as the light module, although obviously essential, is a trivial engineering exercize.

There is no way to guarantee proper connection between the anode and cathode without a short. Unless you insulate the cathode (longer lead) most of the way down except for the last little bit and leave the Anode clear. You'll need to make the foam backboard from a fairly thin layers of thin foam. Cover the top and bottom with this foil tape. Now when the LED pierces the foam the exposed anode will make contact with the top layer. The anode lead needs to be cut short enough that it will not pierce the bottom layer. Then the cathode being insulated most of the way down will not make contact with the top layer but will with the bottom layer. So the foam needs to be thick enough to allow the cathode to pierce all teh way through but not let the anode get through. Attach the possessive lead of the power source to the top layer and the negative to the bottom layer. But you will need to use LEDs that have built in current limiting resistors. You'll also need a power source of about 3V which should cover most 5mm LEDs. You'll want to limit the number of LEDs the board can use and figure out the total current draw they will all have being wired in parallel and get a power source that can support that amount of current. Seams like this could make a good instructable.

Two layers of conductive foam with an isulator between.

One LED long, the other short - the long LED leg needs to be insulated in the area of the upper foam contact.

Just a matter of deciding if you want a long positive or negative leg ;)
Of course it would pay off to have a very low resistance for the foam and the right resistor on the LED.

Unless you find LED's with an built in resistor I would use 12V to power the foam and a resistor on every LED.