There are dozens of different payout systems used in slot machines. In one of the simplest designs, a jackpot is detected by measuring the depth of notches in the discs that drive the reels. For simplicity's sake, we'll look at this sort of payout system in a bare-bones slot machine. The machine only accepts one kind of coin, and there is only one winning combination of images.
When you put a coin in this machine, it falls into a transparent case. The bottom of the case is a movable shutter that is connected to a metal linkage, as you can see in the diagram. Normally, the linkage holds the shutter closed. But when the machine hits the jackpot, the third stopper shifts the linkage up, opening the shutter so the coins fall out of the machine.
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Each of the three discs has notches for each stop position of the reel. The notch for the jackpot stop is deeper than the other stops. Consequently, when the first reel lands on the jackpot stop, the first stopper moves farther to the left than it would for any other stopper. If the second reel stops on the jackpot as well, the second stopper also moves farther left. Same goes for the third reel and stopper.
But if only the second reel stops on the jackpot, the second stopper will not move all the way into the notch. The first stopper has a catch that keeps the second stopper from moving past it. The second stopper, in turn, has a catch that holds the third stopper back. For the third stopper to lock all the way into the jackpot notch, then, the first and second reels would have to have landed on the jackpot image. When this happens, the shutter opens to dump all of the coins that have been played since the last jackpot.
The Science Behind Slot Machines
Typically, slot machines will have more elaborate versions of this design in order to pay out partially on certain combinations of images and pay out completely on the jackpot combination.
In another popular system used in some electrical machines, the discs have a series of metal contacts attached to them. When the reels stop, one of the contacts engages a stationary contact wired to a circuit board. In this way, every stop on each reel will close a different switch in the electrical system. Certain combinations of closed switches (jackpot winners) will configure the machine's electrical circuit to operate the payout mechanism.
A more advanced system uses photoelectric cells (also known as photo diodes), devices that generate a current when exposed to light, to detect the position. In this system, a series of holes are drilled through the rotating discs, all around their outer edges. The photo diode is positioned on one side of the disc, and a light source is positioned on the other side. As the disc turns, the light shines through the holes onto the photo diode. The pattern of holes in the disc causes the photo diode to generate a similar pattern of pulses of electricity. Based on this pattern, an electronic circuit can determine the position of the reel.
Newer slot machines use computers instead of gears. We'll take a look at those next.
On a slot machine, a random number generator (RNG) picks a random number for each reel, which each number matching a stop on its reel. Then the machine directs the reels to stop on the spots selected by the RNG. Note that by the time the reels are spinning, the game is already over.
Originally, casinos installed slot machines as a diversion for casual gamers. Unlike traditional table games (such as blackjack or craps), slot machines don't require any gambling knowledge, and anyone can get in the game with a very small bet.
This idea proved to be a monstrous success -- slot machines eventually moved off the sidelines to become the most popular and the most profitable game in town, bringing in more than 60 percent of the annual gaming profits in the United States.
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Parts Of A Slot Machine
The technology of slot machines has also changed a lot over the years. The classic mechanical designs have been almost completely replaced by computer-controlled machines. But the game has remained the same. The player pulls a handle to rotate a series of reels (typically three) that have pictures printed on them. Winning or losing is determined by which pictures line up with the pay line, a line in the middle of a viewing window. If each reel shows the same winning picture along the pay line, you win (certain single images are sometimes winners as well). The amount you win -- the payout -- depends on which pictures land along the pay line.
In this article, we'll find out what sets the reels in motion in modern slot machines as well as in the old mechanical models. We'll also see what determines the odds of winning on a slot machine and look at some popular variations on the traditional game.
The classic slot machine design works on an elaborate configuration of gears and levers. The central element is a metal shaft, which supports the reels. This shaft is connected to a handle mechanism that gets things moving. A braking system brings the spinning reels to a stop, and sensors communicate the position of the reels to the payout system. A coin detector initially registers that a coin has been inserted and unlocks a brake so the handle can move.
There are any number of ways to arrange these elements, and manufacturers have tried dozens of approaches over the years, so we'll focus on one representative design. The basic design includes three reels mounted on a central shaft. The central shaft also supports three notched discs, which are connected to the three reels. A second shaft below the central shaft supports a kicker, a piece of metal comprising three paddles. The kicker paddles are lined up so they can push against the notches on the three discs. The second shaft also supports a series of connected stoppers, teeth that lock into the notches on the discs.
Make A Slot Machine
The kicker and the stoppers are both connected to springs, which hold them in a standby position. The kicker is held in place behind the discs, while the stoppers are held up against the discs, locking them into place.
Is There A Science To Slot Machines
When you pull the handle on a slot machine, these parts do a lot of work. We'll look at exactly what happens in the next section.