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Tiny LED ring-light

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By: madworm

How to get light onto objects that are close to the lens of a small digital camera.

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Download all project files

Bill of Materials

Qty Part # Description Schematic ID Source
1 209055e79a140837adfbe604533b887443c05192 AO3400A MOSFET N-CH 30V 5.7A SOT23 - AO3400A Q1 Source
1 C63ad0fe873226b724e9f462c579b863dca4528b ERJ-6GEYJ151V RESISTOR, 0805, 150R 5%, 0.125W R17 Source
1 7f9befbd05389e73fafb640725891a74885f44d9 ERJ-6GEYJ104V RESISTOR, 0805, 100K 5%, 0.125W R18 Source
2 0330fe6de5fed8ed451898c7279a9571b8f1b848 ERJ-3GEYJ102V RESISTOR, 1K, 100MW, 5% R18,R19 Source
1 Aa656a6b142318e04865529b5078e470a09fa209 GRM21BR61E475KA12L CAPACITOR, 0805, 4.7UF, 25V C1 Source
16 5ca79b61615f71bd10891d3466ffa6b9f39a8276 ERJ-6GEYJ680V RESISTOR, 0805, 68R 5%, 0.125W R1-R16 Source
16 LED PLCC2 3528 Colour temperature: 6000k Vf: 3.2V @ 25mA D1-D16
2 RS-282G05A3-SM RT SWITCH TACTILE SPST-NO 0.05A 12V SW1, SW2 Source
1 8125410c9c0f9a75503432f791f2b46d1bc4e13e ATTINY13-20SU IC, 8BIT 1K FLASH MCU, SMD, SOIC8 IC1 Source
loading total from bomfire.com...

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1. Measure twice - order PCB once

Although having PCBs made is pretty affordable nowadays, it sucks to receive boards that won't fit. And let's not forget about the time-penality.


2. Separate the boards and upload code

  • Snap the break-away tabs with an old wire-cutter and clean up the edges with a file or sandpaper.
  • Upload the PWM firmware to the micro
  • Dry-fit the ring and measure how much length of wire you need
  • Attach the wires

3. Use Sugru to make a tight-fitting retaining ring

The inner diameter is slightly over-sized. That allows for some manufacturing tolerances and should help to avoid scratching the plastic case of the camera.

To keep the board perfectly centered in place and away from the plastic, Sugru rubber is used to form a retainer ring. It grips to the stationary part of the objective.

To prevent Sugru from permanently sticking to the case during the molding-phase, cling-film is used inbetween it and the case. Care must be taken to get a wrinkle-free layer. Make sure to let the rubber cure for a full 24h hours. It may appear solid on the outside after several hours, but will still be malleable inside. If the board is pulled of too early, Sugru will tear inside and fail to do the job.

A wax-based release agent might work as well, but it comes with the risk of running into the objective and coating the lenses.


4. Take well lit macro shots!

But let's not stop here!

A source of illumination that doesn't block direct line-of-sight is also helpful in microscopy, SMD inspection, looking at stamps...


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3 -
2 - Added Gerber files.
1 - Initial project release
Add revision

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