Thursday, September 20, 2012

Pneumatic Jack in the Box, Part 2

Make sure you view all the videos posted in Part 1 before continuing.

The ELK-120 sound board can pull up to 2A@12VDC and the mouth servo may require more current @5VDC than the Arduino's voltage regulator can support, so I went with a dual-output power supply that provides 12VDC and 5VDC outputs.

However, the Arduino and the DF Robot Relay boards all need 9VDC.

I built a simple voltage regulator circuit using the LM350T voltage regulator IC to drop 12VDC down to 9VDC. I discovered the DF Robot relay boards will draw power from the Arduino when it is only powered by the USB connection to my laptop, so I added a 1N914 diode between the Arduino and the voltage regulator board so the Arduino will only receive power from the voltage regulator's output to which the other boards are also connected.

On the same board I also placed some terminal blocks, pull-down resistors, and unique-value resistors for the Arduino's analog inputs. The accordion head platform position sensor, lid position flex sensor and Insteon InlineLinc trigger input all connect to this "interface" board.

Here are some pictures of the prop with the base, accordion platform, electronics and most of the pneumatics completed. The lid cylinder has not yet been installed.

JITB internals from left side JITB internals from right front corner JITB internals from rear right corner

In the last photo, note the magnet mounted to a strip of aluminum bar attached to one of the drawer slides on the base of the accordion. The magnet moves back and forth between two reed switches which tell the Arduino the position of the head platform. Each reed switch connects to a different unique-value resistor on the interface board which allows both reed switches to work off of a single analog input. When the head is down, one value is read, when it is up, another value is read.

On the rear panel are the connections for power in, air in, an AC outlet for the UV spots (controlled by one of the DF Robot relays) and a weatherproof panel protecting a USB port for external access to adjust the Arduino program (called a "sketch") and a one-amp circuit breaker for the AC outlet. Since I am using (2) 3W UV LED spotlights to light the JITB from two different angles, 120W is more than enough. I was concerned about overloading the 18-gauge internal wiring or the small DF Robot relay assigned to the spotlights. Hence the one-amp breaker.

JITB rear panel connectionsI made a YouTube video explaining how to make the flange mount for the air in connector.

Next I made the left, right, front and top panels out of 1/2" plywood, gave them a coat of Kilz white primer, then projected some art I found on the internet onto them and lightly traced the projected images with a pen. You don't want to trace the outlines with a very dark or thick pen as this will show through the primer and the fluorescent paint.

Here are some pictures of how the panels turned out. They look even brighter under UV light. After painting them, I sprayed them with interior gloss polyurethane to give them some basic protection from damage. Interior polyurethane won't block UV, exterior-grade will. We don't want to block UV since this is fluorescent paint.

Note: Make sure you are done painting before the polyurethane coat! I forgot some dark wash "shadow" lines at the edges of clothing and under the chin on a couple of the panels.

JITB left panel JITB right panel JITB top panel
JITB front panel with motor arbor through eye JITB front panel motor on back of panel On the back of the front panel I mounted a 25RPM Dayton gearmotor from Grainger. A 1/2" thick slab of rubber prevents motor vibration from resonating the panel.

09/25/12: JITB assembled no head - with lid cylinder (featured below)
10/04/12: Clown head with mouth servo

Part 3 will review the animatronic clown head and shoulder assembly.

I am keeping a Parts List for this project updated on Google Docs.

Continue to Pneumatic Jack in the Box, Part 3

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