Introduction: Just a LED

Introduction

This Instructable is sequel to simple LEDs for Breadboards posting in February that solicited a comment like “What can possibly be new about LEDs and breadboards”. A discussion ensued on why presenting mundane, not necessarily new things is often entertaining, for the author as the reader. The point was never resolved but raised the question whether there could possibly be even a more simple presentation of an LED to bolster the argument.

Admittedly a LED is not intrinsically very exciting but does enjoy a certain celebrity status in the Arduino Land. If a sketch were music the “Blink” would be a leading music of the genre.

Finally the inspiration for a simpler presentation surfaced. While performing that often-thankless task of wiring a LED “to see physical output”, the mind drifted over the question of why no one had come up with a “Duct Tape” DIY for the Arduino’s LED appetite. Perhaps is shear desperation to avoid focusing on the task at hand, the next musing was that the “Pink Pearl” eraser used to be touted as the DIY go-to. OK, it was a musing, maybe not “DIY”. In combination for example with a telephone book (another nearly extinct specie) it was used position the slide/movie projector or it could function as a bookmark.

So the gem of an idea, marry the flash of an Arduino’s LED with something that has been eclipsed by the pop-culture icon Duct Tape.

Intention

The motivation for this Instructable was its possible enjoyment by a reader as an example of the sillier side of posting. While that remains foremost, the physical “props’ for the presentation have some appeal in the Gizmo arena. The Instructable therefore will also show the material and methods in constructing a Pink Pearl and LED apparatus for Arduino-ing.

Step 1: Material

  • 1x - Pink Pearl eraser
  • 2x - 680Ω Resistor 1/2W
  • 1x - M-M Dupont F-F connectors (20cm)
  • 1x - F-F Dupont F-F connectors (20cm)
  • 2x - 5mm LED (any colour)
  • 1x - Shrink-wrap black 5mm (3/16”)
  • 1x - Shrink-wrap red 5mm (3/16”)
  • 1x - Utility knife
  • 1x - dash of quick drying glue
  • 2x - drill bits, two sizes (e.g. 3/32” and 1/8”)

  • Solder
  • Soldering iron.
  • Clamping Device

Step 2: Construction

The construction here is intended to produce two Pink Pearl-LEDs. As indicated by the Dupont connectors listed, the M-M would be applicable to the breadboard & Uno and the F-F to power supply & Nano. Obviously hybrids are possible and perhaps there is use for a breadboard & Nano or power supply & UNO.

A 1/2W resistor was chosen to handle the power/heat with the prospect this could be a problem. Although no guarantee can be suggested, heating did not seem to be a problem. For evaluation, a resistor was fitted to the channel running across the eraser, a LED with 1.6V forward voltage was connected to a 12V supply. The eraser did not warm significantly, did not smoulder or burst into flames. The inventory of 1/2W resistors available was not extensive, the 680Ω value was chosen over 470Ω although 560Ω may have been optimum.

Regardless the following are the steps taken for this posting.

  • Cut the Dupont connectors in halves.
  • Strip to 2-3mm of bare wire. Cut the Pink Pearl into halves. With each half drill three holes, two from the slope end, one from the side. One hole from the sloped end should be larger than the other to accommodate the resistor. The holes from the sloped end should be about the same spacing as the LED legs.
  • Cut the eraser from the top edge to the drilled channel. Set aside.
  • Assess the depth of the channel across the Pink Pearl and cut the anode leg but leaving enough leg so the LED body clears the eraser by 3-5mm.
  • Cut one lead of the 680Ω resistor to about 5mm or to match the soldering skills.
  • Solder the anode leg of the LED to the clipped lead. Clip the second lead to 5-7mm.
  • Cut a length of red shrink wrap 10-15mm.
  • Run half-section of Dupont connector through tube.
  • Solder bare wire to resistor lead. Push shrink-wrap to resistor body, apply heat.
  • Cut a length of black shrink wrap.
  • Run half-section of Dupont connector through tube.
  • Solder bare wire to cathode leg of LED.
  • Push shrink wrap to LED body, apply heat

The LED, resistor and ½ Dupont connectors should be as seen in the image. The anode leg of the LED is bare but insulated from the cathode with the shrink-wrap. Next the soldered items must be inserted in the channels made in the eraser by:

  • Form the wire/lead/legs as shown in the image.
  • Push the resistor and connectors into the respective channels.
  • Push the LED leg portion onto the third channels across the eraser.
  • Adjust the form or remove eraser material until the LED is acceptably level and the channels can be squeezed close without distorting the eraser.

The construction can now be glued. Probably in two steps as was done for the Instructable.

  • First glue the two channels closed and after curing will aid applying pressure to the seal the cut across the eraser.
  • Glue and cure the cut across the eraser.

There they are, 2x Just a LED.

Step 3: Summary

This posting is probably on the mark for its intended level of banality but has had a surprising consequence.

As constructed the Gizmos were without the smell of burning synthetic rubber that was a concern. The 10x20x32mm size and naturally non-skid material actually makes each sit well although their very dimensions could also be a working space problem.

If there were to be a version 2, longer connectors would probably come to mind as an improvement but thinking this through for version 1 has been entertaining. Hopefully others feel a response, a smile or shake of the head is welcome.

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