After I saw HOOKED connect a real automotive tachometer to his Stern Mustang, I wanted to do something similar to my HS2 Getaway. I plan on synchronizing the tachometer needle with the playfield tachometer lights. I've also thought about boosting the tachometer needle position every time the ball makes a loop around the supercharger.

I'm pretty inexperienced with electronic design. I was working my way through the opening chapters of the "Make: Electronics" book (great book for learning basic electronics) when I first started thinking about making this. Building this mod has been a great way for me to get practical experience. It's also helped me better appreciate all the work that goes into designing and building all the great aftermarket pinball products that are available to us.

Below are all the videos of a multi-part series documenting my experience designing and building a pinball mod. They're pretty long, but I hope the trials and successes along the way will make them interesting.

Getaway Tach Series: http://www.youtube.com/playlist?list=PLZXypXzuz-W3Nu35rhYS4dh87afp_na9_
All of my pinball videos: http://www.youtube.com/playlist?list=PLZXypXzuz-W1a3N0_SjL0kYL04ukL9sOv

Part 1: Concept and prototyping

Part 2: Integrating with pinball circuitry

Part 3: Schematic and circuit board design

Part 4: Circuit board assembly and bench testing

Part 5: Completion

And finally, here it is in action!

Just realized I had an insert bulb out during filming. How embarrassing!

Part 2 of the series is forthcoming!

I'll post the second video tonight after encode and upload. Part 1 covered design and prototype of tachometer control. Part 2 covers the integration of the tachometer with Getaway's lamp matrix.

Here's the latest schematic. It's grown a bit since the sketch I showed in the first video. I hope I'm not getting in over my head when it comes time to lay out the circuit board.

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Part 2 is posted! In this new video, I connect the tachometer to the lamp matrix, drive the tachometer using a playfield lamp, and begin to formalize the schematic.

...next video will cover fabrication.

Yeah, the tach is a toy, but the shift light will actually add to the game. I can see forgetting to shift when you're busy, especially in multiball, but you're not going to forget to shift with a shift light. They're really bright! It'd be fun (and mean!) if i could get the shift light to flash during Redline Mania. The last thing you need in a mania mode is a blinding light flashing at you.

I finished the layout and routing of the PCB, sent it out for fabrication, and ordered all the components to populate the boards. Exciting!

Latest schematic:
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PCB (red is top layer, blue is bottom):
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Fancy 3D views:
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Just received the first of what will be several parts orders.

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Boards are in!

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Getting pretty close! I ran some tests on the populated board last night and everything works! ...except for the +12V LED which I mounted backwards. Otherwise, microcontroller and debug header works, tachometer sweeps, shift light works, and the optos work and the micro can sense when lamps are on or off.

Just need to figure out where I'm going to mount the tachometer and the shift light, figure out where I'm going to mount the board, figure out how I'm going to power it, make some cables, and get everything mounted.

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Part 3 is posted. In this new video I finalize the electronic design, draw the formal schematic, layout the printed circuit board (PCB), and submit it for fabrication.

Thanks for the interest, guys! I need to get it working, figure out where to mount it, figure out how to power it, and make sure it's reliable before I consider selling it. It's pretty close. Making cables this week and then I'll be ready to hook it up to the machine for the first time.

Part 4 is posted. In this new video, I replace my old tachometer with a new flashy one (that goes to 10!), assemble the circuit board, and bench test the circuit board to ensure everything is working.

Part 5 is posted. In this new video I playtest the circuit and microcontroller code, optimize the code, install the tachometer and shift light on the playfield, and install the circuit board in the machine. Everything works!

Here's part 6 that shows the tachometer and shift light in action!