Gottlieb Hot Rod - a tribute to classic EM pinball

(Topic ID: 214665)

Gottlieb Hot Rod - a tribute to classic EM pinball


By jwilson

7 months ago



Topic Stats

  • 75 posts
  • 53 Pinsiders participating
  • Latest reply 5 days ago by rufessor
  • Topic is favorited by 34 Pinsiders

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    There are 75 posts in this topic. You are on page 2 of 2.
    #51 7 months ago

    It is REALLY cool!

    I want to play it more! Hope to see it out again! Great job on this project!

    2 weeks later
    #52 6 months ago

    You could always bring it to pintastic. It's only a short 7h 40 min drive. I would love to see this in real life. I've also said multiple times that I owe you a beer or two, so why not bring it out east a little bit? Fantastic very professional looking work. It makes me rethink my use of auto clear and using a sponge brush and lots of sanding. Congratulations again on all your hard work.

    #53 6 months ago

    Astonishing ! Congrats !

    A little technical question: if i am not mistaken, the coils in a Gottlieb EM are originally powered by 25 VAC.
    You explain here above that you are using 24 VDC.
    By rectifying 25 VAC, you get about 35 VDC.
    The MOSFETs have a negligable voltage drop
    So by what means do you produce 24 VDC ? Do you use an external SMPS ? Or do you use the recitified 25 VAC (so, 35 VDC) for the coils ?

    If so, don't you fear to overdrive and overheat the coils ?

    #54 6 months ago
    Quoted from PinheadBE:

    By rectifying 25 VAC, you get about 35 VDC.

    That's still much lower than most modern games (50-70V).

    I'm using the original EM transformer and a custom-built rectifier board to convert the 6.3VAC and 24VAC to DC to power the coils and lamps. Coils are never on long enough to overheat, and the flippers are PWMed down to about 10% power.

    Game logic is run from a separate 5V switching supply.

    #55 6 months ago
    Quoted from jwilson:

    That's still much lower than most modern games (50-70V)

    Yes, but that's not the point: modern games are equipped with coils designed to be driven by 50 - 70 V.
    Your game has coils designed to work under 24 VAC.

    Over a given period of time, the energy conveyed by DC is already higher than the energy conveyed by AC given the same voltage
    Energy over time is power
    So, driving a 25 VAC coil with 25 VDC will already produce a much higher power (both mechanical and heat dissipated).
    But driving that very same coil with 35 VDC will definitevely put it under a lot of stress.

    And not only the coil, but also the mechanics associated to it.
    if you ever got a bent bumper leg which causes the bumber to remain stuck and quickly turn into a barbecue starter, you definitively will risk it now
    And I'm not even talking about broken plastics

    In this article, you will read an example of calculation on how to drive a coil designed for 120 VAC with DC.
    The result is.... 34 VDC !
    http://www.ecmweb.com/content/using-ac-coils-dc-power

    I don't want to argue, but as you can see, I'm afraid you are taking some risks....

    As about coils that will overheat, of course, it appears very rarely under normal conditions.
    But you have to take into account the failure mode of your components.
    Since MOSFET's failure mode is, in 90% of the cases turning dead short, your PWM is voided and your coil receives a full hit of the power supply
    Furthermore, the High voltage rail may be sent back through the Mosfet's gate to the driver circuit, causing more failures in both the command circuitry (if not isolated through an opto-coupler) and causing a total collapse of the PWM circuitry.

    If I were you, I would have an in-depth look on that awesome design of yours, just to be sure to not have it plagued by recurrent technical issues

    #56 6 months ago
    Quoted from ejacques:

    Amazing work! Put me in line to buy a copy of the translite should you decide to make more....that would look awesome lit up on my gameroom wall!

    X2

    Great job, it played great at MGC. Thanks for bringing it out for us to enjoy!

    #57 6 months ago

    I appreciate what you’re saying but I’ve been working on this game for over four years. I’ve got a pretty good handle on it.

    All coils are run at the absolutely smallest duration where the mechs still work - about 7ms for the score reels as an example. Things hit about as hard as the original game in high tap, since I prefer the snappier pops.

    Lastly, this game is destined to sit in my game room and get played maybe once or twice a week - it’s not going on location. I haven’t popped an IRL540 yet but if I do, it’s all fused and I’ll be there to turn the game off.

    #58 6 months ago
    Quoted from PinheadBE:

    If I were you, I would have an in-depth look on that awesome design of yours, just to be sure to not have it plagued by recurrent technical issues

    Duly noted.

    #59 6 months ago

    Just to reiterate Jeremy's point... he is able to configure the width of the pulse sent to the MOSFET to kick the solenoid. The width of the pulse can be programmed within +/- .5ms. (Actually most tests I have seen it is within +/-.1 ms) That level of control was never available on EM or even early SS machines. The timing is controlled by the gap of the switch leaves. How Jeremy does it, that is not applicable since the pulse width is controlled by a microprocessor. The processor also guarantees that the switch must be deactivated before it can be activated again. Lastly there is a dead time feature to prevent shotgunning.

    1 week later
    #60 5 months ago

    You're assuming that nothing will ever fail.
    I assume that, for example, the µC or anything in the interface between it and the Mosfet can fail or get stalled. Your PWM can be switched on 100% by a program bug
    Even a short kick at 100% is strong enough to put the coil sleeve under mechanical stress since it was not designed for that
    If your mosfet dies, the 35 VDC will be sent back through the gate to the driver circuit to your 5V rail and fry out just about everything on your board (unless the signal is fed through an opto-coupler to avoid that, but as you didn't mentionned that, i suppose it is not the case).

    On the same subject, may I suggest you read https://hackaday.com/2018/05/23/mechanisms-solenoids/ , specially this part:
    "While any solenoid will run on AC or DC, care needs to be taken to observe the coil’s specs. Solenoids represent an inductive load, and so their impedance is much higher in AC applications. So if a solenoid rated for 24 VAC were powered by 24 VDC, it would probably burn out quickly as the current through it would exceed the design specs. This could be avoided with a current limiting resistor or by lowering the DC supply voltage."
    (Note that I personnaly disagree with the current limiting resistor suggestion)

    #61 5 months ago

    Coils are activated for milliseconds. They're not burning out.

    I don't see you going into the WPC repair forum and telling people that they're going to burn out their coils when those TIP102 transistors blow. I just wonder why you keep coming here to tell me stuff I already know and have said is fine.

    #62 5 months ago

    Hey Jeremy,
    So how are those coils doing?

    #63 5 months ago

    Such great work!!

    #64 5 months ago
    Quoted from BobLangelius:

    Hey Jeremy,
    So how are those coils doing?

    Coils still coiled.

    3 weeks later
    #65 5 months ago

    So, I thought this saga was complete, but I ran into some issues. I announced an official tournament for my game in a month and started prepping things for it, then discovered that the OPP boards couldn't handle the network load I was throwing at them - all the light shows, coil hits and switch triggers caused it to drop packets, putting the game into weird states where it would launch extra balls or display lights wrong, or switches stuck on.

    It was too late to cancel the tournament, so I made a drastic decision - to completely replace all the electronics with P-ROC boards.

    Unfortunately, P-ROC doesn't have a direct lamp control option, only a lamp matrix one, so I was forced to essentially re-wire the machine from scratch.

    Here's a photo of it in progress. All told I needed 9 boards - P3-ROC, three SW-16s, two PD-16s - score reels alone need 8 drivers - and two PD-8x8s to drive the 107 individual lamps.

    Re-wire in progress

    Having never done a lamp matrix before, it was a daunting process. But I managed to get it neatly packaged. Here's the backbox board.

    Backbox board

    I also had to replace my homemade power supply, as I needed different voltages than it would provide - 12V for switches, 24V for lamps.

    My first 24V power supply was DOA, then the next one didn't have enough juice to fire the drop reset. I replaced it with an adjustable 48V one set to 36V.

    Three power supplies

    Success! The matrix was almost 100% on the first try. Cross-wired a couple of lamps but that was easily fixed. A shot of the working backbox.

    Pretty lights

    But now the big issue was that the software - Mission Pinball Framework - wouldn't run on the Raspberry Pi 3 I have to drive the P-ROC boards. But thanks to the diligent work of Jan Kantert, the lead developer on MPF, he got it working 100%!

    So the game is now fully operational and ready for the tournament this Thursday at Cabin Fever in Toronto. If you're interested, here's the link.

    https://www.facebook.com/events/223830728202211/

    #66 5 months ago

    Is that a Jenkins Electric bell?

    #67 5 months ago

    It's a 24V bell from some random IGT slot machine.

    #68 5 months ago

    Holy smokes - your a whiz ! Quite the rework on your great re theme. Very impressive.

    I'd bet you could design and build your own game from scratch !

    #69 4 months ago

    Very impressive.

    #70 4 months ago

    We had the tournament this past Thursday - the First Annual Hot Rod Pinball Nationals!

    It was held at our local pinball bar Cabin Fever and was set up as a "Queueball" format: head-to-head, winner gets a point, loser stays and plays the next person on the list. It worked surprisingly well!

    Here's some photos from the event. The game performed surprisingly well despite some software issues. Hardware was perfect.

    Set up and ready for a night of competition! 3-ball play, disabled the match, 8 degrees! Played mean.

    At Cabin Fever

    Competition begins!

    Robyn racking up points

    It was fierce! So many close games!

    Sorry, no bonus this time

    Everyone absolutely loved the game - people commented that the brutal EM playfield and resulting ball times were vastly improved with the addition of a ball save, and that the additional features like lane change and a hard but not totally unattainable goal like the 2-ball and 3-ball multiballs really brought an amazing level of complexity to a game that didn't even have powered slings when I started.

    Facinating

    People would stand around and watch others play as the game really evened out people's chances - instead of being strongly biased to the highest skilled players, the game is about 50% skill and 50% luck. So even "okay" players had a strong chance at winning.

    The Queueball format meant a decent wait until you got to play again, which was thankfully offset by having all the other games to play, the buffet spread, drinks and good company.

    Good times.

    In the end we had 11 people competing and everyone had a great time!

    #71 4 months ago

    Not Sure how I missed this thread, but WOWZERZ very, very cool. That backglass is AMAZING!
    Great job man!

    #72 4 months ago

    Just read thread start to finish. Simply amazing work. What vision you had from the very start!
    Congrats. It's beautiful!

    1 week later
    #73 4 months ago

    I will be setting Hot Rod up at the Toronto Maker Festival this weekend, and as part of the booth I thought I might run the game software from a laptop so people could see it. That means I'll have a screen for a display, so I whipped up a quick attract mode and game mode display. Here's a demo.

    If you're in the Toronto area, you are welcome to come down and check it out in person. I'll be at the Toronto Reference Library Sat/Sun 10am-5pm.

    3 months later
    #74 23 days ago

    The highlight of Expo for me was this machine. Excellent work sir!

    2 weeks later
    #75 5 days ago

    Absolutely amazing work. This type of project is totally on my radar and your work is an inspiration to many, myself included.

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