Introduction: RGB LED Light Writing Wand

Following on from my previous instructable, I have an interest in long exposure photography. The tools to do this tend to be on the pricey side, so I decided to make a couple of my own.

NOTE: I wanted RGB and white, however the chip will not light up white (RGB at the same time). I believe it to be because of one of 2 reasons; 1. The chip does not accept 3 channels of current at once. or 2. The 9v provided is not enough forward voltage to power all 3 channels at once. The pictures in this instructable will show 4 buttons, however I shall disregard the white button and only refer to 3 (RGB). I could add another battery, such as 1.5v aaa/aa in series with the white button to boost the voltage only when the white button is pressed. However as I did not test until the end of the soldering process, I had already cut my PVC pipe too short to allow additions.

This wand is designed to give the user easy control of colour whilst in use, without having multiple tools or heads to change.

A total of six colours can be achieved using single or a combination of two buttons.

Step 1: Tools and Materials

Equipment

  • Soldering Iron
  • Solder
  • Wire Strippers
  • Electrical Tape
  • Pliers
  • Tweezers
  • Screw Driver(s)
  • Scissors
  • Drill/ Rotary multitool
  • 16mm hole saw

Materials

  • 1" PVC tube Approx. 200mm length/8"
  • RGB LED (10w) Amazon link
  • Household LED (Small/golf ball) - I used a cheap £2 one from toolstation however it is this type Amazon link
  • 16mm momentary push buttons (Coloured 1 x red, 1 x green, 1 x blue) eBay link
  • 9v battery
  • 9v battery connector
  • Thermal conductive glue

Note - Not all bulbs are equal. They do not all have the same type of heatsink, some are cupped and others are flat. For this project a cupped one is required.

Step 2: Prepare PVC Pipe

The PVC pipe I had available was grey in colour so I decided to spray paint it black. I would suggest (if you haven't already) taking the Instructables PVC class, it gives you most things you need to know about working with PVC.

I decided on 1" as it fits a 9v square battery in snugly without additional fixings. The heatsink I had also was a snug fit once the pipe's edge was bevelled slightly.

The length of the PVC pipe ended up at approx. 200mm/8"

Step 3: Cut the PVC Pipe

Using a hole saw that matches the diameter of you buttons (in my case 16mm), cut 3 holes in the pipe in a straight line with enough room between them for the external part of the buttons.

The hole saw will leave rough edges so using a knife/deburring tool, carefully neaten the holes.

At this point, test fit the buttons to ensure the holes are not too big/small.

Step 4: Break Down Household Bulb

The reason the bulb is required is purely for the diffuser and the heatsink contained inside. There are most likely alternatives for these items however I could not find/think of any at the time.

To break this down I used small flat screwdrivers and pliers. Prising the metal cap from the base, removing the inner electronics and diffuser (be careful not to damage) and outer plastic casing. I also tried using a rotary tool with cutting blade to allow the diffuser to come loose, however I only found it useful for starting to get a lip to get the screwdriver under.
This should leave you with a metal heatsink with LEDs attached and the plastic diffuser. Remove the LEDs from the heatsink via the two screws and clean the top from thermal compound. This is now the main base to build onto.

At this point, the heatsink I had had 3 holes; 2 small for screws and a larger on in-between. I decided to drill a hole opposite the larger hole and use these as cable channels, with the larger one being for R G B -ve and the smaller for +ve.

Step 5: Add RGB LED Chip

Using the thermal conductive glue attach the LED to the heatsink, aligning the -ve pins with the large hole and the +ve pin with the small hole.

I then used electrical tape to secure the chip to the heatsink whilst the adhesive sets to allow me to continue.

I would suggest prior to soldering that you test the LED to;

1) Ensure the chips works

2) Find +ve and -ve if they arrive with no documentation

3) Confirm which pin is which colour

Solder the corresponding coloured wire to the correct pin, using enough wire so that when fed through the PVC tube at least 1" is visible out of the tube end to allow for easier soldering to the buttons contacts.

Feed the wires through the holes in the heatsink.

At this point you can add the heatsink to the PVC tube. As mine was a snug fit I bevelled the edge with a sander to allow the two units to slide together easier. I also secured it with electrical tape.

Step 6: Solder the Buttons

I decided to keep the buttons in RGB order as for easy operation when in dark conditions.

Pull the corresponding wire through the hole where the button will be for that colour, allowing for enough slack to be able to strip and solder the internal wire, cut the wire.

Use the loose piece of wire and solder it to one contact on the button. Solder the wire on the inside of the pipe to the other contact.

Feed the loose wire back into the tube through the button hole and push the button into place. I then used a dab of hot glue to secure the button.

Repeat this for all 3 buttons.

Step 7: Add Power Source

Solder the -ve RGB wires to the -ve wire on the 9v connector and the +ve wire to the +ve wire on the connector.

Once soldered, push the battery into the bottom of the PVC pipe. This could be secured with an end cap.

Step 8: Attach Diffuser

The final step is to attach the diffuser.

Remove the electrical tape holding the LED in place if you have not done so already.

To ensure that the diffuser is securely attached I used the thermal conductive glue, superglue, hot glue and electrical tape allowing each to dry before the next. I wasn't sure what would work best for metal to plastic bonding and I had very little available to me.

Step 9: Complete!

The unit is now complete and ready to be used.

This again is a low tech, basic tool but it works and is cheap.

It is multipurpose and could also have the tips switched out.

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Bio: Photographer with a Forensic Science degree.
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