Thursday, October 30, 2008 Ohio State Reformatory

We visited the Ohio State Reformatory site in September 2008. The structure and tour were absolutely fascinating.

The Casket Cleaned Up

The amount of rodent waste accumulated inside the casket eliminated any potential to keep it in original condition. A bio-hazard style cleaning was necessary.

The clean up brought out the beauty of the box. The box and lid are built of 3/4" pine boards and would accommodate a person up to a height of 5' 11". That would probably cover most folks in 1920s.

The box tapers from bottom to top in all dimensions. Exterior dimensions at the base are 73-1/2" length by 19" width. At the top the box measures 77" length by 22-1/8" width. The sides and ends are solid boards of 11-1/4" height. Two boards of 9-1/2" width compose the bottom of the box.

The lid is constructed of two 11" wide boards overlapped by a 9-1/2" board. Overall dimensions of the lid are 77-1/2" length by 22-3/4" width.

The lid is secured to the box with four rather decorative thumb screws. This was a cool and surprising detail.

The Casket

An account of the acquisition of a vintage casket.

"M. V. Wright Funeral Director" operated from a small carriage house in Troy, Virginia in the 1920s.

A good friend preparing the building for demolition found a few artifacts.

This sign hung in front of the carriage house.

The nameplates are all that remain from the old horse-drawn hearse.

And in the rafters was a pine casket. Apparently a deluxe model with a black fabric exterior finish and fully upholstered interior (with straw padding). This casket is mentioned in a 1966 article about Mr. Wright, copied below.

Windshield Wiper Motor

Let's take a moment and reflect on the unappreciated windshield wiper motor. Great torque, dual windings, quiet operation for under $20 - this baby is made for Halloween. The wiper motor as removed from the car has a 'park' position that gives you a clunk every revolution. It is simple to open the case of the gear assembly and take out the cam that caused the thump. I mounted mine to a 3/4" plywood base that has proven handy for installing the motor to a variety of props. It also helps electrically isolate the motor case (DC ground) from any other AC prop accessories, such as the PC power supply below.

This is the schematic for the entire wiper/washer circuit in a GM vehicle. The wiper/washer switch is not part of the wiper motor assembly but is included because it identifies the function of timer and cycle switches built into the motor assembly. The only connections that I have used for props are the Purple (+12 volt for high speed), Yellow (+12 volt for low speed) and Black (12 volt chassis ground). These wires all come from a three-pin connector on the motor itself. Note that you would connect either the Purple wire or the Yellow wire to +12 volt, depending on your desired speed, but never both.

Scary Terry - Wiper Motor

Howstuffworks - Wipers

PC Power Supply

The great companion to the wiper motor - an old PC power supply. This one provides three output voltages rated at 10 amp each - 12v (yellow wires), 5v (red wires), and 3.3v (orange wires). The great thing is that the three output voltages and the wiper motor 's dual windings in combination produce quite a range of RPMs. For instance, the 5 volt output connected to the low RPM motor wire produced the perfect speed for the Flying Crank Ghost.

I mounted a nylon terminal strip to the case of the power supply and terminated the output wires there to make it easier to use in a variety of props.


Here is a simple cycle control circuit for a two-stage prop. Requires two 12 volt relays and two momentary switches (with "normally closed" terminals).

Switch 1 is mounted to be actuated when the prop is in the "at rest" position. Switch 2 is mounted to be actuated when the prop arrives at the "full scare" position. A negative trigger (either from you or a motion sensor, etc.) causes Relay 1 to 'latch', and in turn activates the Relay 2 to provide 12 volt power to the wiper motor. When the prop pops up or does whatever its thing is and hits Switch 2, the latched relay deactivates and stops the motor. The prop is then reset by a second negative trigger (either from you or a timer) which provides power to the motor to return the prop to its ready position.

If your prop requires just one cycle - meaning it triggers, does its thing and returns to its original position in one continuous motion, only one momentary switch would be needed.

This configuration worked quite well and was cheap to make. NOTE: the 12-volt power feed needs to be fused for safety.

This control circuit was posted on the HauntForum by TommaHawk. It offers all of the functionality of the first circuit and adds the ability to reverse the polarity (and therefore dir
ection) of the motor.

This is an old hack that I did to a cheap RC car in order to use the radio control circuit to control a larger prop powered by two wiper motors and a lawn tractor battery. It actually worked well, given the limited range of the toy. I ended up doubling the length of the receiving antenna and that helped. This completely mobile style of prop is fun, but really offers potential for injury.

You Gotta Love Relays!

A relay is an electromechanical device that uses an electromagnetic coil (electro) to move switch contacts (mechanical). The coil can be energized with a small amount of current, while the switch contacts can be used for a number of applications, including switching, isolating, or polarity reversal of high current circuits.

Power transistors have gained popularity for high current switching, but lack the flexibility of the “make and break” functions of the relay.

A typical 12-volt relay requires a coil current of .150 Amps to energize. The relay contacts can switch currents up to 30 Amps, creating a power gain as high as 200 to 1.

The classic automotive relay is the Bosch E5000. There are many variations of this design, but thankfully most manufacturers follow a standard nomenclature.

The Coil
Terminals 85 and 86 form the coil contacts. As current is passed through the coil, a magnetic field is produced, which actuates the switch contacts, causing terminals 30 and 87 to close. In order to pass current through the coil, 12 Volts must be applied to one side of the coil while Ground is present on the other. Most relay manufacturers recommend that terminal 85 should be connected to Ground, and 86 should receive 12V, but in fact the coil is non-polarized and either connection works. The only time polarity must be observed is when a “quenching diode” has been installed across the coil terminals.

The Contacts
Terminals 30, 87A and 87 form the contacts. When the relay is at rest, terminals 30 (Common) and 87A (Normally Closed) are connected. After the relay coil is energized, terminal 30 breaks its connection to 87A, and makes a connection to terminal 87 (Normally Open). Knowing this action of the contacts allows you to apply the relay in various configurations to achieve the desired results.

Common Types of Automotive Relays
are identified by poles (the number of isolated common contacts) and throws (the number of isolated connections that the wiper arm contacts). The classic relay is a single-pole (one common contact) double-throw (one normally-open and one normally-closed contact), or SPDT.

Positive Trigger to a Negative Output

Converting a Negative Trigger to a Positive Output

Using Relays To Reverse Polarity

20 Second Recorder

We needed an audio source that was recordable, repeatable and could be remotely triggered. Our first thought of hacking a CD or MP3 player seemed impractical at the time based on cost.

Radio Shack's 20-Second Recording Module proved an affordable solution at $11. The unit is a small circuit board that comes with an attached 16-ohm speaker (for recording and playback), tiny circuit board mounted record switch and 9-volt battery clip.

The idea is to push and hold the record button (LED confirms status), speak loudly into the speaker then release record button. One push of the play button on the main board provides tinny playback.

To make this low-fi device useful, we need to:

  • tap the play button with two wires to trigger play
  • replace the speaker with a mini jack to connect to a PC (recording) and an a mp (playback)
  • attach power wires and wean this thing off 9-volt batteries
  • fit the whole shebang in some kind of protective box.

A little experimenting proved that the recorder operated fine from 5-volts. We will be using a PC power supply to power a 12-volt prop, so we already had 5-volts with nothing to do. Cutting off the 9-volt battery clip and splicing a length of wire on each lead takes care of power. The wire attached for power and ground will be about 18" long and should provide for many splices into different applications.

The play button can be visually traced. One pole connects to ground near the power connection, and the other pole connects to the switch side of resistor R3. So, a length of small gauge wire soldered to each location provide remote trigger inputs.

The mini jack connector that I had was salvaged from a PC. It was a stereo-mini and although this is a very mono device I soldered both positive leads from the stereo-mini to the positive speaker output of the board. The braided shield from the stereo-mini jack was soldered to the negative speaker output of the board. The connection nearest the "SPK" silkscreen was identified as positive based on a "+" marking on the speaker terminal.

An old Altoids tin seemed an appropriate enclosure. Three holes drilled in the sides and she was good to go. The stereo mini jack was threaded and mounted with a panel nut. I cut a grommet in half to protect the power and trigger wires where they passed through. The circuit board is secured by four big globs of hot melt glue. These adhere it in place and stand it off the tin a bit to eliminate any chance for shorts. Hot melt to each wire pass through provided a bit of stress relief and insulation.

At the last minute we extended the record switch wires so that it could be mounted to the lid. This keeps it protected through normal use (an accidental push erases your audio!), but still handy for recording.

The few modifications are simple and do improve functionality. Mounting it in a tin seemed to reduce the unit's susceptibility to interference. This had caused some erratic triggering from nearby devices, most notably a fog machine.

Practical application finds our little Altoids box hooked up to a PC power supply for 5-VDC, with the trigger wires extended to a relay mounted inside an animated prop, and its stereo mini output connected to a car amplifier driving two 6X9 speakers. What we lack in audio quality can be made up in volume.

In the end the results are satisfactory. Experimenting with PC level setting when recording the audio produced ample output volume. Sound quality is poor - think telephone - so selecting a simple audio track with limited or compressed frequency range gives better results. It is useful enough that we made two.

Pop Up Corpse

Here are a few pictures of our first motorized prop. The project started with a frame from an old stationary bike, a broken weedeater, a wiper motor from a Buick Skylark and a $20 'talking bride' skull. The bride skull would cycle through three corny songs that were useless for scaring tots, but was equipped with an articulated jaw driven by a 5-volt motor. We wanted a corpse that would pop-up fast and say/scream something with synchronized jaw movement, did not want to spend more than $50, and did not have an air compressor. And so the design criteria were set.

This is the frame of the corpse in the rest position. The mechanical elements and hands are completed. His spine is the weedeater - the curve of the aluminum frame provided a good offset to attach the linkage from the drive arm. The main frame is the stationary bike, chosen because it already had good bushings where the pedals were mounted. The bushings were easy to re-use as the pivot point below the corpse's pelvis. The rest of the armature is old aluminum from other projects. Also visible is the wooden frame of the toe-pincher coffin, to be finished with cardboard (I know, I know) stapled to this frame.

Here is the corpse in the upright position with his scare full on. The theory is that once he reaches this position, an evil laugh (courtesy of Vincent Price) will be played from CD, complete with synchronized jaw movement and flashing yellow eyes. We will see...
His hands are the classic coat hanger wire, duct tape and glue-soaked paper towel technique. The fingernails are cut from a milk jug.

Raising the left arm was a simple matter of mounting it on all-thread, then adding a length of aluminum angle stock parallel to the spine with a pivot point slightly offset from the spine's. The right arm was to move sideways, and required a bit of clunky engineering. There are six pivoting joints in the assembly that transfers the vertical motion to the lateral motion that we needed. No way this could fail under repeated use, right?

Two end-of-cycle switches were required to stop the motor when the corpse was fully reclined and then again when he achieves the full upright position. Initial tests of controlling the motor directly through the switches showed that the cam would not park at the right spot to keep the switch open. The result was the corpse most often thrashing up and down continuously, nearly beating itself to death.

This was solved by using two 12-volt relays: one wired to 'latch' when it receives a negative pulse (until either switch is actuated) and in turn activating the second to provide 12-volt power to the wiper motor. The configuration worked quite well and was cheap. NOTE: the 12 volt power feed needs to be fused for safety!

A final treatment of glue-soaked paper towel has been applied to the head and hands, tinted with food color. The cardboard neck and a little of his chest received the same. The torso and arms have been filled out with chicken wire. We dressed him with a t-shirt to hide the mesh pattern, then a muddy dress shirt, and finished out the coffin with cardboard, foam and some old curtains. The foot of the coffin is left incomplete because we will install a chicken wire mound and cover with leaves and debris. This will hopefully create the impression that the coffin is jutting up out of the ground.

He moves pretty quick from activation to full upright position with the whole cycle taking less than 2 seconds. The motion has considerable force, which caused me to abandon motion-triggered activation, as there would be no barrier between him and the tots. No point in risking injury to anyone! Besides, I would have just sat and watched him scare people anyway.

Sorry that there are no photos of the inside of the head. After researching the normal circuits and endless douglas fir tree hacks I landed on a simple solution to synchronizing the jaw to audio: driving the motor directly from an amplified audio signal. How can you drive a DC motor and DC LEDs from an AC audio signal? By connecting the speaker outputs of one channel from a car CD receiver to a bridge rectifier (essentially four diodes, much like a car alternator uses to convert its AC output to DC) and then the outputs of the rectifier to the 5-volt DC motor and lights. This does present an odd (low impedance) load to the amplifier, and initial testing with an 8-ohm home receiver caused it to pop into protect mode at higher volume. The 4-ohm stable CD receiver that we used Halloween night performed well. Adjusting the balance control allowed shifting more power to the left (jaw motor) channel without overpowering the actual audio output of the right (speaker) channel. If our audio system had not included a balance adjustment, we could have increased the gain of the left channel before burning the disc.

Wednesday, October 29, 2008 The Grave Grabber

The Grave Grabber sitting on the floor. His head and hands are recycled from our 2003 Pop-up Corpse project, so check out that page for cosmetic details.

Grave Grabber (rear view) with his shirt off. This is a super simple animation and he worked reliably for five hours of continuous operation. The armature is primarily aluminum "L" channel and some steel flat bar.

Better views of the crank and motor assembly.

Here the Grabber is lying on his back and this is the bottom of the base showing the motor. The red and black wi
res draped over the wooden frame powered LEDs in the Grabber's eyes.

The Ghost Video

The "Flying Crank Ghost" has got to be the best documented Halloween prop out there. I wondered why people were fanatical about the Ghost until we built one. Everyone that saw it liked it.

This video shows the Ghost as she appeared "live".

The Ghost

Here is our finished ghost figure lying on the ground. She is a wire armature with cheesecloth and two old curtains as her shroud. We washed the material in RIT whitening so that it would fluoresce under blacklight.

Her armature is (of course) coat hanger bent into basic shape with free moving loop joints at shoulders and elbows. We taped all exposed ends of the coat hanger to prevent the shroud from snagging.

Her hands are little girl's 'glamor gloves' from the dollar bin stretched over coathanger fingers and stuffed with batting. The wrists are taped to the wire forearm, and the sleeves of the shroud are hot-glued to the top of the gloves.

Her face is a Mardi Gras mask (around $4) with cheesecloth glued over the contour of the face with enough excess material to form a veil over the rest of the head. We stuffed a white grocery bag full of other bags to form a ball to round out the back of the cranium. Then we poked the coat hanger throu
gh the bag-ball to form the hook with which to hang her. Some strips ripped into the cheesecloth and tied behind the bag-ball held it all together. We also put a strip of black duct tape on the bag-ball behind the eyes of the mask to make them appear hollow.

The marionette mechanism (bottom view) is just an "I" frame of aluminum "L" channel. The white reflector at the bottom of the picture is a blacklight mounted to the frame. We did this because she was going to be mounted high above the spectators and there was no good alternative for moun
ting the blacklight.The dimensions of the frame were based on the spacing that we desired between her hands and the forward distance of her hands to her body. The rear cross member is much longer than necessary - I don't cut to length unless necessary. The spacing of the two central cross members was based on the width of the wiper motor's plywood platform since it was already assembled from previous props.

This is a top view of the mechanism, showing the motor and power supply. Initially we mounted the pulleys securely to the frame, because they were pivoting pulleys. The line jumped the pulleys consistently, so we tied the pulleys loosely with nylon rope instead, and they moved much more freely and never failed. The Ghost operated outdoors in difficult weather with 20 MPH wind gusts, but never had any trouble.

Black boot laces proved to be a cheap and functional line to tether the Ghost to the crank pivot.

Here is a side vie
w of the mechanism, showing some detail of the motor and power supply.