Connect with us

Anyone here know how an one-armed bandit (slot machine) works?

Discussion in 'Electronic Design' started by Guy Fawkes, Oct 28, 2006.

Scroll to continue with content
  1. Guy Fawkes

    Guy Fawkes Guest

    I was wondering what kind of electronics are inside a slot machine and how
    the circuitry works. As an engineer I would think that it has some MCU
    inside with a random number generator and a simple algorithm which has a
    fixed percentage (chance) of winning and losing.

    The problem is that some gamblers seem to think that their chance of winning
    depends on how much money's in the machine (i.e. the weight of the coins).
    This makes them think that they can 'beat' the system and win, even though
    they can't. OTOH I reasoned that if a machine has a fixed chance of winnings
    then it may run into problems when the machine is empty and someone hits the
    jackpot, the machine then wouldn't be able to pay out the winnings.

    So do the winnings of these machines depend on the weight of the coins
    inside of them?

    Thanks in advance, Guy
  2. Google for articles on how to cheat them - best source of info?
  3. Baron

    Baron Guest

    Thats a fair assessment !
    NO !
  4. Robert Baer

    Robert Baer Guest

    I would think not.
    Take the extreme case you mentioned, and the sucker won a jackpot.
    The machine would send an alert that would be recognozed by the
    casino workers, and the casino would make good on the jackpot.
    Probably the machine would be "primed" or filled with the minimum
    jackpot amount; large jackpots are never paid by the machine anyway.
  5. jasen

    jasen Guest

    some of them are DOS based PCs with, 2 to 8 Megs of rom-disk
    I think there are two (or more) seperate coin reservoirs
    Immediately after someone has taken the pot it may do
  6. JoeBloe

    JoeBloe Guest

    I think all you guys are silly.

    Here's how they work.

    1) You put in your money...

    2) It takes your money...

    3) Each state has laws on how often it has to pay a jackpot. It
    could be a 100,000 pulls... less... more...

    They count on all the little pay offs being put back in so line one
    and line two above are the most true.

    The only truly random "One Armed Bandits" are the old, fully
    mechanical versions. They give you the best odds of hitting the pot.

    They cycled like one out of every three coins to the main payoff pot
    till it gets full. The others go into the house pan and short payoff
    tubes. Then, it was just a matter of time and luck.

    These new electronic versions are real bandits, that's for sure.
    I'll take Roulette any day.
  7. Rich Grise

    Rich Grise Guest

    I saw a thing on TeeVee the other day - I think the show was "Masterminds" -
    about some guy who hit a bunch of slots in Vegas for a couple of million
    dollars. It was a very sophisticated hack. The guy had about a dozen
    accomplices, who blocked the view while he used a skeleton key to open
    an access panel and a stick to stick a piggy-back sort of ICP on the
    game's micro or EEPROM, and program it so that the next play would be a
    jackpot. He'd button the machine back up, put the stick back in his
    pocket, and go outside. The dozen or so accomplices would continue to
    mill around, except for the designated winner, who'd hit the jackpot, and
    the hack was smart enough to reset itself, so everybody thought it was
    a real jackpot.

    The only reason they got caught was because the mastermind guy was getting
    an incredibly huge percentage - like 75% - and the goons were splitting
    the rest, so one of them flipped him. Caught by gold fever! ;-)


  8. The moral to this story, of course, being: "If you're going to turn to
    a life of crime, be sure to pay your help more than the competition does."

  9. Baron

    Baron Guest

    Belive me those mechanical machines were anything but random. You could
    control the drums quite accurately to determine payouts. In fact it
    was quite common to set them up to give lots of small wins and very few
    or no large ones ! The Jennings and Chieftan machines were a joy to
    work on !
    I would agree with you ! Electronics and micro's have allowed much
    better control than was possible with mechanics !
  10. That would leave too much to chance ;-)

    Here (DK) the machines are legally required to pay out 80% of the money put in
    and they are tested by the IRS. So if a machine has not paid out any winnings
    for a long time the probabilities are adjusted. The machines also rat to the IRS
    about winnings/takings - just to keep things "fair".

    There is usually a red button to call the attendant on such a rare occasion.
    A.F.A.I.K. Not really, in the Casino they just *might*: It is good advertising
    if someone occasionally pulls down a million!
  11. Guest

    If memory serves, in Nevada, for instance, the law only requires that a
    game be random. I personally, would be surprised, if casinos even
    comply with that. Most of my gambling experience goes back 30 years,
    and it wasn't with slots, but I would bet that nowadays, they probably
    plug slots into a PC to make adjustments, or the slot has a friendly
    GUI built into it, or both.
  12. GregS

    GregS Guest

    I didn't realize the slots went to stepper motors and CPU's until my
    brother bought one and I had a view of the inside. I don't know what years
    they switched from pure mechanical. Probably when they had some
    good CPU's. I alwasy used to pull the handle, and at different speeds.
    Now I just push the button. Most of todays slots do not drop coins back out at all.
    Its gone to credit type cards or other tokens.
    Much of the sounds have vanished. Many machines will not payout until
    a certain amount of money has collected. This payout extends to
    many of those skill type machines going for prizes like cameras.
    It would seem the card game machines also have the same type of
    rules. When I go to Vegas, I usually put in my allocated $20, and
    thats it.

  13. GregS

    GregS Guest

    I forgot to explain the obvious. Some slots are set to payout a lot of small
    rewards, and not really pay out anything big. Slots
    near entrances and isles command tne most attention. I have sat at
    some sets of slots and seemed to play for hours, and then returning to
    the same machines later, I last about 5 minutes. They go through cycles.

  14. Rich Grise

    Rich Grise Guest


    I wouldn't. I've worked around the gaming industry in the past, and they
    go to great lengths to make sure the games are "honest" - i.e.,
    everybody's got the same chance of winning, which, as it happens, is
    less than 1.0. ;-) With the number of gamblers, it doesn't have to be
    biased by very much to be a guaranteed win, over time, for the house.

    Good Luck! ;-)
  15. GregS

    GregS Guest

    I use to have an old pinball machine. I got it on a trade of a Lionel transformer.
    The machine had a bad transformer. I used to go out shopping at the local Olsen
    Radio store. I go there one day anfd was looking in the parts section. i see a transformer
    labeled somthing to effect of pinball transformer. it had all of the 4 or 5 voltages
    my machine needed. The part I never got was how this mechanical box gizmo inside, separated by the other
    things worked. I thought it was some kind of payout decision making thing, but
    thats all I know. Perhaps it controlled currents to rotary mechanisms.

  16. Guest

    That is correct. The casinos use simple math to insure they get rich.
    With the volume of money that flows through these machines it doesn't
    take much of a statistical edge to keep the owners rich. They can tune
    the machines to give a healthy balance of big and small payouts simply
    by how the different games play, but the overall margin stays roughly
    the same.
    The player will pick the type of machine and the bet to adjust what
    kind of payoff they want.
    Think of the lottery. If you want to win small payouts often you play
    scratch tickets. If you just want to take a chance on a huge payday
    but lose a lot, you play powerball. The overall payout is about the
    same (typically 50%). That makes the state lotteries the worst bet you
    can play. The guy on the corner selling "numbers" is a better deal.
    They usually pay out a higher percentage and it is tax free money.
    Casinos will be paying out a whole lot better than a lottery. They
    count on you staying there long enough for the odds to catch up on
    you. The smart play in a casino is to play until you are ahead and
    leave. Nobody does.
  17. Thants not quite right. Look at your stepper reels and the symbols and
    you can calulate the probability of winning any given prize. Each
    wheel is spun completely randomly. The new vdeo machines work on the
    same principle, except the wheel is simulated.
  18. Actually, none are DOS based. Most run proprietary software. Some run
    linux and one manufacturer use embedded XP.
    Not quite. One coin hopper in the machine. When that is full the coins
    drop to a conveyor or a bucket under the machine.
    Nope. Its all completley random.
  19. We have these slot machine display mechanisms available on eBay.


    when untruncated.

    They are legal anywhere as they are only the display and stepper mechanism.

    The steppers include a homing position sensor in the form of a one bit
    shaft encoder.

    Cleaned, refurbed, all bulbs good.

    These are a perfect beginner's PIC project.

    Many thanks,

    Don Lancaster voice phone: (928)428-4073
    Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
    rss: email:

    Please visit my GURU's LAIR web site at
  20. And where do you suggest we find a perfect beginner?

Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day