Crate Beast - Effects And Controller

Don't get too close to that crate! There's a monster inside!

WARNING: If you are considering this project, read all Related Pages before you start!

Block Diagram
Prop-1 controller
Pneumatics
Trigger
Sounds
Lights
Fog
Related Pages

Block Diagram

Here is a block diagram of the effects and controls, when the whole thing is completed:

On the successive refinement, we will build the parts that are practical now, and add the rest later.

All of the control equipment was mounted on scrap pieces of leftover masonite. One board contained the pneumatic equipment: pressure regulator, distribution manifold, valves, flow regulators and mufflers, and solenoid driver (Parallax EFX DC-16 Digital Output Board). The other board contains the Prop-1 controller and sound equipment. There are only two connections between the two boards: power and a thin control signal cable.

The various printed circuit boards were mounted on hexagonal aluminum standoffs, threaded for #4-40 bolts. The bolts that we used have 1/4" of thread.

This is a mockup of the main control board, with the major components just sitting on the piece of masonite.

Prop-1 controller

The Crate Beast is an intelligent prop with control managed by a PROP-1 type microcontroller.

The Prop-1's Inputs and Outputs are allocated as follows:

Input
- Beast Trigger - Input bit that tells the Prop-1 to launch a Beast attack.
- Lid Trigger - Input bit that tells the Prop-1 to rattle the lid.
Output
- OpenDoors - Output bit that opens the doors at the end of the crate.
- PushBeast - Output bit that pushes the Beast out of the crate.
- OpenLid - Output bit that pushes up the crate lid.
- PushClaws - Output bit that pushes the claws out of the open lid.
- SoundControl - Serial I/O to the sound board.
- ShootFog - Output bit that triggers the fog machine.

For reasons mentioned elsewhere, we need more outputs than a PROP-1 provides. We decided to use a Parallax DC-16 Digital Output Board to add more bits.
The DC-16 board takes a single input signal and uses it to drive up to 16 solenoids.

This was a pre-production prototype board generously provided by the nice folks at Parallax EFX.

Pneumatics

We have another page for the pneumatics details. But since the controller drives the solenoid valves, we'll provide a little info here.

The particular solenoid valves that we used (Mead LTV-120) require two signals each: one signal to push the valve open; another signal to push the valve closed. When there is no signal, the valve stays in the last position you put it in. That means we need eight output drivers just for the four solenoids. We decided to use a Parallax DC-16 Digital Output Board to add more bits. The DC-16 board takes a single input signal and uses it to drive up to 16 solenoids.

We decided to mount the DC-16 with the rest of the pneumatic components, with a single control cable running from the Prop-1 to the DC-16.

Looking at the solenoid coils:

24 VDC - marked
120-ohm - measured resistance
.2A - computed current draw

In order to support these solenoids, we decided to power the Prop-1 using a wall wart with the following characteristics:

24 VDC
2+ Amps
2.1 mm connector [required to fit the Prop-1]
center-positive [required to fit the Prop-1]

Trigger

It would be easy to make the crate automatically trigger when somebody is nearby. In the future, we might actually do this.

The problem with fully automatic operation is that the doors swing open rapidly and the Beast jumps out with force. You don't want to trigger the Beast when some kid is trying to peek into the crate. This requires a lot of safety mechanisms.

For now decided on manual remote control. We trigger it via X-10.

This puts a "man in the loop": the crate only gets triggered when a human sees that it is safe and presses the button.

There are actually two X-10 trigger signals: one rattles the lid, the other makes the beast attack.

Sounds

The Crate has its own sound system that combines a continuous "ambient" sound track (of snuffling, growling noises to make the crate seem occupied) with extra loud roars triggered on demand when the Beast strikes.

Both sound tracks are mixed together and are played through amplified speakers.

This Audiologic portable CD player was purchased at Fry's for $20 (September 1999).

We bought four of them for spot sound in various haunt locations and decided to put one in the crate for the "ambient" sound track.

The extra loud roars are digitally canned sounds, played through a Parallax EFX AP-8 board.

Lights

The Crate contains a red lamp to give the illusion that the Beast has glowing red eyes, or perhaps breathes fire.

Rather than put in a light that's on all the time, we wanted to give it some life. So we fed the audio channels into a color organ.

The color organ is not under the direct control of the Prop-1 controller. It simply listens to the combined sound track, part of which is triggered by the Prop-1.

Fog

The crate emits some smoke from time to time, giving that the impression that the Beast either breathes fire, or something else powerful and unpleasant is going on.

The fog effect is created with a glycol fogger which fires on demand from the Prop-1 controller.

More details on the Crate Beast:

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