Build your own Light Painter

Club Jameco Designed Kit

Description: Touch Sensitive Light Painter
Difficulty: Beginner
Time Required: 2 hours
Designer: diybrian

Light painting is a photographic technique that captures light in motion at slow shutter speeds. The light painter has 5 different colors all controlled by a MOSFET-based momentary touch switch and is powered by a 9V battery.

This project is a beginning level project that should take about 2 hours. You can buy the kit or discuss the kit at ClubJameco.com

Build your own Light Painter

Required tools and parts:

Soldering iron and lead-free solder
Wire strippers/cutters
Hot glue gun and glue sticks
Drill
Heatshrink tubing and gun

Kit Includes:

Qty.	Description	Mfr. Part No.
5	Green LED	LG3330
5	Yellow LED	LY3330
5	Transistor	2N7000
1	9V Battery	ALK 9V 522
2	White LED	MCDL-5013UWC
1	Proto Board	22-512
5	Red LED	UT1871-81-M1-R
10	Resistor 20Ω	CF1/4W200JRC
10	Resistor 82Ω	CF1/4W820JRC
10	Resistor 10MΩ	CF1/4W106JRC
1	Battery Snap	BAT-SNAP-4
5	Blue LED	LTL-2R3CBD3

Light Painter

Step-by-Step Instructions

Step 1 – Positioning and drilling into the case

First you need to decide on the location of the touch switches and LEDs. Use four red, four yellow, two green, two blue, and two white LEDs. Using one LED per color will allow you to use a smaller case and create more solid lines when you paint. If you use RGB LEDs, you can produce a wide range of colors by varying the resistor values.

Holes for LEDs

Holes for touch switch

Step 2 – Installing the touch switch

The touch switch is a momentary switch with N-channel MOSFETs. When you touch the anode (+ terminal) and gate, it will turn ON. Touch sensitive switches respond instantaneously and allow you to use multiple colors at the same time.

In this circuit, there are six wires which are the electrodes. Since MOSFETs rely on charging their internal capacitors to turn ON, they need to be discharged before it will turn OFF. The 10M resistors will discharge them. A smaller enclosure (and circuit board) is preferred.

Solder the MOSFETs, wires and 10M resistors to the board. For metal cases, make sure to insulate underneath the PCB with a sheet of plastic. If you need to grind the PCB, wear a safety mask and protective eyewear.

LED and touch switch

Circuit board for the touch switches

1. Common anode (solder wire here)
2. red (on) electrode
3. blue (on) electrode
4. green (on) electrode
5. yellow (on) electrode
6. white (on) electrode
7. 2N7000
8. 10M discharge resistor
9. Touch switch circuit
10. Current limiting resistor
11. LEDs

Step 3 – Attach the LEDs to the case

To attach the LEDs, line up the LEDs with long pins (anode) facing the short pins (cathode) and glue them into the drilled holes with epoxy. Allow them to set before soldering them.

Step 4 – Calculating the Resistor Values

The resistor values were selected for 20 mA LEDs. You can calculate the resistance values here: http://led.linear1.org/1led.wiz (1/4 watt works fine).

Step 5 - Soldering the LEDs

To solder the LEDs, bend the leads so that their anodes (long pins) and cathodes (short pins) touch each other. Solder them in series to a resistor.

Glue LEDs in with epoxy

Solder anodes to cathodes of LEDs

Solder resistors in heat shrink tubing

Step 6 – Building the electrodes for the switches

Cut wires long enough to thread into the holes with the case fully opened. Solder the wires as shown in the diagram. The wires sticking out should be stripped and tinned. To make the contacts larger, you can mold some solder on the wires. Since you will be handling them, the solder must be lead free. Hot glue the wires to the case. If the case is conductive, you may use hot glue to insulate it from the wires. Avoid coating the electrodes with hot glue.

Twist and solder wires

Glue the wires to the case

Step 7 – Mounting the PCB

To mount the PCB, you can either use hot glue or bolts.

Step 8 – Tips on Light Painting

To light paint, set the shutter speed to long exposure - the longer the better. Mount your camera onto a tripod. A timer may be useful.

About the designer

Brian Yong enjoys working with microcontrollers and LEDs in his garage workshop. He has other projects on Instructables.com. He is currently studying electronics at BCIT (British Columbia Institute of Technology). Other hobbies include running, tennis, cycling, and gardening.

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