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  • Author Author: wolfgangfriedrich
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wolfgangfriedrich

I decided to explore the artistic PCB realm and the map location pin became the theme.

A reverse mounted red LED, powered by a CR2032 coin cell, is shining through the PCB to provide a bright homing beacon.

 

Soon also available in blue.

 

The 1st installment is the classic maps pin inspired by your favorite 'show me the way' tool.  The 2nd version has the outline of the more modern icon that can be found everywhere by now, even on my milk carton.

image

The reverse mounted LED is driven by a 3V coin cell through a simple 200 Ohm current limiting resistor. This provides ~5mA for the LED to balance brightness against battery life. A micro-switch can turn the LED on and off without the need to remove the battery,easily accessible on the top of the pin.

The batteries I have tested lasted more than 6 hours at reasonable brightness with a measured current of >2mA. And then it is running for another 24 hours at 2 to 1mA and still the LED is shining considerably bright through the PCB.

imageimage

 

A circuit for a quasi-constant current supply is also designed onto the board, to run the LED from 5-20V without a battery. Here the LED can also be controlled by an additional external signal.  This requires wires soldered to the pin and makes not as mobile but would be a good option for a more permanent wearable installation. Details about this circuit are documented here.

 

The boards were manufactured by Seed Studio (Classic version) and JLCPCB (Modern).

 

They are not_a_badge and if you really like them, they are available for sale in my Tindie shop image.

 

I sell on Tindie

 

- W.

 

PS:  Don't get lost. image

  • Wolfgang,

     

    A really neat and inspiring project. It spins off all sorts of possibilities.

     

    Dubbie

  • in reply to Fred27

    Thanks for the kind words.

    Yes, big plans. I will sell thousands of them and people will not be lost any more because they know where they are and I become super rich image.

    The real thing looks even better than the photo, because the center is also shining red and not so white'ish. Red-green-blue LEDs could become a white pixel when there is enough distance to the viewer. But then it would probably be better to use an integrated LED. Colour separation could be done by stiching vias between LEDs. Even better would be a 4 layer board with guard traces around each LED on all 4 layers (there goes another patent).

     

    Cheers,

    - W.

  • That's a great fun project. Do you have any specific plans for them?

     

    I used a reverse mount RGB LED shining through the PCB substrate on a recent project. Great for a nice diffuse light. You can also define hard edges using the copper layer. The only thing I can imagine wouldn't work well would be to have a few close together. I suspect you'd get light bleed that you would be able to control.

  • in reply to genebren

    They are red LEDs, the forward voltage for white ones would be too high to be run off a coin cell.

    No, nothing is 3D printed, just a PCB and components.

    I make a little bit of money, if I don't think about my time. And for a simple gadget like this, I don't think people would buy it at a higher price. The biggest reward is, to know that people like the stuff and are willing to pay some money, while I have fun building it. The biggest pain is the shipping cost from Canada Post, their rates for small packets and the fact they don't let anything other than paper being shipped as a letter internationally.

     

    - W.

  • in reply to wolfgangfriedrich

    The LED light through the PCB is pretty cool.  Did you use a red or white LED?  Are the cases 3D printed?  Do you feel like you make any money on tindie at these prices?

     

    Gene