Painting with Light: Build a Light PainterDescription: Touch Sensitive Light Painter
Time Required: 2 hours
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
Required tools and parts:
Soldering iron and lead-free solder
Hot glue gun and glue sticks
Heatshrink tubing and gun
|Description||Mfr. Part No.|
|9V Battery||ALK 9V 522|
Step 1 – Positioning and drilling into the caseFirst 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.
Step 2 – Installing the touch switchThe 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.
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
8. 10M discharge resistor
9. Touch switch circuit
10. Current limiting resistor
Step 3 – Attach the LEDs to the caseTo 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 ValuesThe 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 LEDsTo 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.
Step 6 – Building the electrodes for the switchesCut 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.
Step 7 – Mounting the PCBTo mount the PCB, you can either use hot glue or bolts.
Step 8 – Tips on Light PaintingTo 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 designerBrian 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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