Intro: Multi-Color Light Painter (Touch Sensitive)
Step 1: Materials and Tools
Enclosure (eg. pen case)
Lead free solder
1 x 9V battery
1 x 9V battery clip
5 x 2N7000 N-channel MOSFET
5 x 10M resistors
Heat shrink tubing
4 x 5mm red LEDs
4 x 5mm yellow LEDs
2 x 5mm green LEDs
2 x 5mm blue LEDs
2 x 5mm white LEDs
2 x 20 ohm resistors
3 x 82 ohm resistors
Quick setting epoxy
Hot glue gun
Step 2: Drill Holes on the Case
Drill holes for the LEDs and wires.
Step 3: Touch Switch
The touch switch here is a momentary switch which uses N-channel MOSFETs. When you touch +9V and gate, the LEDs turn on. The MOSFET requires up to 3 volts to turn on. Compared to mechanical switches, 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. The 10M resistors allow the MOSFETs to turn off when you release the switches.
Update: 20 ohm resistors can be used for the red and yellow LEDs. 82 ohm resistors can be used for the green, blue, and white LEDs.
Step 4: Attach LEDs to the Case
Attach LEDs using epoxy. Allow them to set before soldering.
Step 5: Solder the LEDs
Step 6: Electrodes for the Switch
To make the switches, strip the wires and coat it with lead free solder. Solder the wires to the gate of each MOSFET. Hot glue the wires to the case. If the case is conductive, you may use hot glue to insulate it from the wires.
Tip: If you have scarp solder, this is where you can use it.
Step 7: Mount the PCB
Step 8: Light Paint
To light paint, set the shutter speed to long exposure and use a timer. Mount your camera onto a tripod. The photos below were taken under slow shutter speed (10 seconds). The longer the exposure, the better. You can also use an RGB LED to produce other colors.