Williams Pinball Inspired Panaplex Clock

You know I am into pinball, but did you know the first classic pinball I played was a Williams? Well here I make a clock inspired by it. Let me take you through how I made it...

You will need the following:

• A printed circuit board for the clock
• A Beckman SP-492 panaplex display (or similar, can be purchased at Marco Pinball)
• Seven 1k resistors
• Seven 1.5k resistors
• Four 10k resistors
• Four 100k resistors
• Two 240k resistors
• Eleven MPSA42 NPN transistors
• Four MPSA92 PNP transistors
• An L7805 5V regulator
• An NCH6300HV Nixie boost converter
• A tip positive 9V 2A supply (typically used for Arduino)
• A DS1307 I²C RTC module
• A CR2032 battery (usually included with the RTC module)
• An Arduino Pro Mini, ATMEGA328P 5V 16MHz
• An FTDI board with USB cable to upload the code
• An MC14543 (or MC14558) CMOS BCD to seven segment decoder
• Wire
• 6"×36" planks (purchased from Hobby Lobby)
• A saw
• Acrylic paint (colors vary depending on design)
• Something to cut the hole for the DC jack
• Hot glue and hot glue gun
• Sticker paper (for labels)
• Clear acrylic
• Hobby knife
• Cardstock (for stencils, may also 3D print the stencils for longevity)
• M2 and M3 screws
• Precision screwdriver set
• Multimeter

Think about how you want to design the case. With sixteen different possibilities, it can be difficult to choose just one.

The sixteen different designs span across three different generations of Williams pinball MPU. Have a look at each design and choose the one you like, then miniaturize it to fit your case.

Stencil PDFs to come in an update.

Alternatively, if you do not wish to cut the stencils from cardstock, you can have the stencils 3D printed, or 3D print them yourself.

STL files to come in an update.

Cut out the following pieces of wood:

• 1 × 1.5"×6"
• 2 × 2"×6"
• 2 × 6" square

Also cut a 1.5"×6" window out of the clear acrylic.

Carefully cut a hole in the 1.5"×6" piece of wood for the barrel jack.

Paint all of the wood pieces with the background color paint as specified:

• Hot Tip: white
• Lucky Seven: yellow
• World Cup: white
• Contact: blue
• Disco Fever: blue
• Pokerino: red
• Phoenix: fuchsia
• Flash: black
• Stellar Wars: black
• Tri Zone: red
• Time Warp: blue
• Gorgar: black
• Laser Ball: red
• Firepower: black
• Blackout: black
• Scorpion: red

Then, follow the color guide for the stencils for each layer of detailing paint.

After letting the paint dry, assemble the case using M2 self-tapping screws, with M3 screws for the top. Use hot glue around the edges of the acrylic to mount it, but leave the top, as we need to load the electronics through there.

Choose whether you want to apply hot glue for the feet or apply proper rubber feet.

Print labels on sticker paper, cut them out, and apply them to the case.

Red labels go under the top, and the appropriate black label goes on the bottom.

The display itself is a neon plasma discharge display, Beckman model SP-492. Yours may be a different brand and model number, but it still works the same. Williams used these displays from 1977 to 1980 to show scores, credits, ball in play, and match numbers in every display unit. This project "hacks" it to show the time of day.

Note that the pin spacing is too wide for this display to be breadboarded. Use a set of DuPont female-ended wires to test this display from a breadboard.

A word of warning, these displays require a high voltage in the neighborhood of 190V to illuminate. Mishandling such a voltage could lead to fatal injuries. By following these instructions, you hereby accept the risk of serious electric shock from high voltage.

The trick here is to control the high voltage to illuminate the segments we want to see to show the time, but with 5V signals, this will be challenging. Read on to see how this will all piece together.

In order to get 5V to our logic and Arduino from a 9V supply, we need to use a 5V regulator. This is where the L7805 comes into play.

Connect the +9V line to pin 1 and ground to pin 2. From there pin 3 will output +5V and pin 2 will be the ground pin.

This is the device we will be using to generate our high voltage for our display. It is meant for Nixie tubes but can drive a planar neon display as well.

Power the device with 9V while shorting SHDN to VIN and, while measuring the output with a multimeter, adjust the voltage until you get a reading of 190-200V. (WARNING: After disconnecting power, the capacitors will still carry a charge. DO NOT try to handle the board until it is fully discharged!)

To drive the segments, we simply use one MPSA42 transistor per segment, with a 1k resistor on each emitter and a 1.5k resistor on each collector. When 5V is applied to the base of any driver transistor, it switches on the desired segment.

The digit anodes need two transistors each, an MPSA42 for the level shifter and an MPSA92 for the driver. The base of each MPSA42 gets a 10k resistor and the base of each MPSA92 gets a 100k resistor. A 5V signal on the MPSA42's base resistor switches on the desired anode at 190V.

The keep-alive cathodes are needed when multiplexing a neon planar display. But they need a very low current to glow. So, route 240k resistors to ground and connect them to these cathodes. The high voltage line goes directly to the anodes.

This clock has two options for the seven-segment decoder used. It can either use an MC14543 latching decoder or an MC14558 ripple blanking decoder.

The truth table for the MC14543 is as follows:

 # | A B C D E F G
---+--------------
 0 | 1 1 1 1 1 1 0
 1 | 0 1 1 0 0 0 0
 2 | 1 1 0 1 1 0 1
 3 | 1 1 1 1 0 0 1
 4 | 0 1 1 0 0 1 1
 5 | 1 0 1 1 0 1 1
 6 | 1 0 1 1 1 1 1
 7 | 1 1 1 0 0 0 0
 8 | 1 1 1 1 1 1 1
 9 | 1 1 1 1 0 1 1
10 | 0 0 0 0 0 0 0
11 | 0 0 0 0 0 0 0
12 | 0 0 0 0 0 0 0
13 | 0 0 0 0 0 0 0
14 | 0 0 0 0 0 0 0
15 | 0 0 0 0 0 0 0

The truth table for the MC14558 is as follows:

 # | A B C D E F G
---+--------------
 0 | 1 1 1 1 1 1 0
 1 | 0 1 1 0 0 0 0
 2 | 1 1 0 1 1 0 1
 3 | 1 1 1 1 0 0 1
 4 | 0 1 1 0 0 1 1
 5 | 1 0 1 1 0 1 1
 6 | 0 0 1 1 1 1 1
 7 | 1 1 1 0 0 0 0
 8 | 1 1 1 1 1 1 1
 9 | 1 1 1 0 0 1 1
10 | 0 0 0 0 0 0 0
11 | 0 0 0 0 0 0 0
12 | 0 0 0 0 0 0 0
13 | 0 0 0 0 0 0 0
14 | 0 0 0 0 0 0 0
15 | 0 0 0 0 0 0 0

If you choose to have the tails present on the "6" and "9", use the MC14543; if not, use the MC14558.

CAUTION: These chips use CMOS logic, and are easily damaged by electrostatic discharge. Be sure to ground yourself to avoid any damage to the chips.

The DS1307 module helps the clock keep track of the time and stores it in memory. A CR2032 battery backs up the time, so you should not need to reprogram the time until the battery needs replacing.

The SDL and SCA pins communicate with the Arduino through I²C protocol, and power is supplied from the microcontroller as well.

The design is provided on the EasyEDA website. You should be able to download the Gerber file and purchase PCBs from JLC, PCBWay, or another supplier.

Solder all the discrete components as marked in the schematic first.

Solder the header pins onto the Arduino Pro Mini and the DS1307 module, then solder them onto the board.

Solder the socket for the IC into place. If using the MC14543, solder on U12; if using the MC14558, solder on U14. Then plug in the IC and solder the display in place.

Wire up the barrel jack and solder it in.

Solder the boost converter and hot glue it to the bottom of the case.

Secure the main board to the bottom of the case with M2 screws.

Hot glue the barrel jack in and plug in the clock. Nothing will happen unless code is programmed into the Arduino. Once code is programmed into the clock it should set itself.

Download the code below and upload it to the clock.

Close the top and admire your new clock!