By Doug Lowe

The figure shows the fully assembled prop controller used to control a jack-in-the-box prop (also shown in second figure). As you can see, the prop controller is made from three circuit boards, which you can purchase from EFX-TEK.

The boards are mounted on an 8×10-inch sheet of Plexiglas, which you can purchase from most hardware stores. Before mounting the components on Plexiglas, spray-paint the back of the Plexiglas black to create a nice, professional-looking board.

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The assembled animatronic prop controller.
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The jack-in-the-box prop.

Here’s a complete list of the parts you’ll need to build the prop controller:

Quantity Description
1 EFX-TEK Prop-1 controller
1 EFX-TEK PIR sensor (includes a 14-inch extension cable for connecting to the Prop-1)
1 EFX-TEK AP – 16 + audio player
1 EFX-TEK RC-4 relay control board
2 Crydom D2W203F solid-state relays
3 EFX-TEK stand-off kits (each kit includes four 5/8-inch stand-offs and eight 4-40 machine screws)
2 14-inch servo-style extension cables
2 6-inch lengths of 16-gauge stranded wire
1 8×10-inch sheet of 3/16-inch Plexiglas
1 Can of black spray paint

All these components except the wire, Plexiglas, and the paint can be ordered from EFX-TEK. The total price for all components should be around $275.

The following paragraphs describe the four main components of the prop controller, which are listed first in the parts list:

  • Prop-1 controller: The brains of the prop controller. This inexpensive controller board ($39.95) contains a BASIC Stamp microcontroller and two I/O busses that give you direct access to the BASIC Stamp’s eight I/O pins. The first bus is a series of three-pin headers that you can connect standard servo cables to. These connectors provide a TTL interface to the BASIC Stamp and are used for low-current applications such as communicating with other prop-control elements.

    The second bus is for high-current applications that can handle up to 500 mA. These outputs can be used to directly drive small motors, relays, solenoid valves, and so on.

    The Prop-1 also includes a 5 V regulated power supply and a programming interface so you can connect it directly to your computer to download programs.

  • PIR sensor: An inexpensive (under $10) motion detector that can be connected via a three-pin servo cable to any of the Prop-1’s low-current I/O pins. This device is used to trigger the prop’s action.
  • AP – 16 + audio player: At $129.95, the audio player is the most expensive component of the prop controller. However, sound is an essential element of any good prop, and the AP – 16 + is an extremely versatile sound player. It can play sounds in WAV format directly from a micro-SD card and includes a built-in 20 W amplifier, so you can connect speakers directly to the AP – 16 + without using a separate amplifier. The AP – 16 + also connects to the Prop-1 via a three-pin servo cable. This connection allows the Prop-1 to send commands to the AP – 16 + to tell the AP – 16 + to play specific sound files on the micro-SD card.
  • RC-4 relay control: This module lets you control up to four line-voltage (120 VAC) circuits by using solid-state relays. It connects to the Prop-1 via a three-pin servo cable, enabling the Prop-1 to send commands to the RC-4 to tell it to turn its relays on or off under program control.

The prop controller uses line-level voltages that can hurt or even kill you if you aren’t careful. Make sure that the line-level wiring is properly secured and enclosed, and never work on the controller board when the line-level circuits are plugged in.

Here are the steps to assemble the prop controller:

  1. Paint one side of the Plexiglas with the black spray paint and allow the paint to dry.
  2. Drill the necessary mounting holes in the Plexiglas.
    You’ll need to drill four mounting holes for each of the three boards that will be mounted to the Plexiglas (Prop-1, RC-4, and AP – 16 +). Use a 3/16-inch drill bit. The figure is a rough drilling guide, but note that this diagram isn’t to scale. You’ll need to lay your actual components out on the Plexiglas to determine the exact drilling locations.
    electronics-mount
    Where to mount the circuit boards and drill the mounting holes for the animatronic prop controller.
  3. Mount the Prop-1 controller on the Plexiglas.
    Use four of the stand-offs and eight of the 4/40 machine screws. Position the Prop-1 controller so that the row of screw terminal connectors is on the left side of the controller as oriented.
  4. Mount the RC-4 board on the Plexiglas.
    Use four of the stand-offs and eight of the 4-40 machine screws. Position the RC-4 board so that the four screw-terminal connectors are at the bottom of the board as oriented.
  5. Mount the AP – 16 + board on the Plexiglas.
    Use four of the stand-offs and eight of the 4-40 machine screws. Position the AP – 16 + board so that the audio output connectors are at the bottom of the board as oriented.
  6. Use the two wires to connect the V + and GND terminals on the Prop-1 to the V + and GND terminals on the AP – 16 + board.
    These wires are used to provide power for the AP – 16 + board. After test-fitting the wires, cut them to the correct length and strip 3/8 inch of insulation off each end. Then insert each end of the wire into the appropriate screw terminal and tighten the screw to ensure a solid connection.
  7. Use one of the extension cables to connect the P7 header on the Prop-1 controller to the SER header on the RC-4.
    This cable enables the Prop-1 controller to send commands to the RC-4 board to cause the RC-4 board to turn its relays on or off.

    Eight three-pin headers are found near the center of the Prop-1 controller board. These headers provide access to the eight I/O ports of the BASIC Stamp microprocessor. The headers are labeled P0 through P7, so you shouldn’t have trouble finding the correct header.

    There are two three-pin headers on the RC-4 board, both labeled SER. These two headers are connected to one another, so it doesn’t matter which one you use as they’re electrically the same.

    The only trick to connecting the extension cable is making sure you get them oriented correctly. The extension cable has three wires: white, red, and black. The cables must be inserted into the header correctly, or the Prop-1 won’t be able to communicate with the RC-4.

    Orienting the cable correctly on the Prop-1 is easy because the three-pin headers are labeled to indicate which pin is white, which is red, and which is black. On the RC-4, the cable should be inserted into the header with the black wire facing the outside edge of the board and the white wire facing the center of the board.

  8. Use the second extension cable to connect the empty SER header on the RC-4 board to one of the SERIAL headers on the AP – 16 + board.

    The purpose of this connection is to enable the Prop-1 controller to communicate with the AP – 16 + audio player to tell it when to play its sounds.

    As oriented in Figure 3-5, the SERIAL header pins are located near the top-right corner of the AP – 16 + board. The pins on the AP – 16 + headers are labeled W, R, and B, so you should have no trouble orienting the wire colors. As with the RC-4, there are two SERIAL headers on the AP – 16 +; it doesn’t matter which of them you use.

  9. Use the third extension cable to connect the PIR sensor to the P6 header on the Prop-1 controller.

    The P6 header is right next to the P7 header.
  10. Insert the two Crydom solid-state relays in the K1 and K2 positions on the RC-4 board.
    Note that if your prop needs to control more than two 120 VAC circuits, you can add up to four Crydom relays to the RC-4 board. And you can add additional RC-4 boards if you need to control more than four circuits.