Youtor
Exploring an arcade roulette wheel mechanism
>> YOUR LINK HERE: ___ http://youtube.com/watch?v=luxD8mNc5sA
This is the motorised roulette wheel mechanism out of a huge six player arcade machine. This type of machine has been around since I was a kid, but the technology has evolved greatly. • The first units had a mains motor and cam-switch sequencer that spun the wheel and then waited for the ball to land in one of the indents. Each indent had a switch in it, and there were slip rings to allow the machine to detect which colour had been landed on. • The machines are notable for their very characteristic coin acceptors. You place your coin vertically into a slot of the chosen colour, and it initially sticks up, allowing you to change your mind and swap it to another position. When the wheel starts spinning a solenoid/magnet system in each play position makes a loud clack noise and lets all the coins drop past simple coin rejectors and switches that latch the chosen colour. • The next era of machines had a hole in each indent position and a bright light above, and used light sensors to get a reference position and detect the ball. • The current era use an infrared sensor to detect the wheel position and an inductive sensor to detect the ball, counting stepper motor steps to determine its position on the wheel. I would guess that the software can detect a missing/stuck ball that doesn't land, and also tampering if it detects something unexpected. It might be quite hard to tamper anyway, since the machine rotates twice to check the ball is in the same indent before paying out. If it has moved indent it keeps rotating until the ball has settled reliably into one position for two full rotations. • I roughed up a test circuit with a PIC microcontroller switching the stepper motor via a ULN2803 octal Darlington driver, with each channel powered by two parallel outputs. The stepper was sequenced one winding at a time, and even with soft speed ramps it took a much higher voltage to get reliable rotation at high enough speed to launch the ball. I think that as long as it can get the ball out of the indent it will be batted by other indents to get the ball into orbit. • Even at the higher voltage the current was just under 1A on a motor rated 5V/1A per winding, and remained cool. Perhaps using MOSFETs for more solid switching would have been more efficient. • I calculated the stepper to ball-indent ratio at 40 steps per wheel position. That's based on 25 positions in a 360 degree sweep and a stepper motor with 1.8 degree steps geared down 5 to 1. • Here are some video links to see the full machine in action:- • • whittakers roulette classic 2P PLAY s... • • whittakers roulette - 2p retro arcade... • If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:- • http://www.bigclive.com/coffee.htm • This also keeps the channel independent of YouTube's advertising algorithms allowing it to be a bit more dangerous and naughty. • #ElectronicsCreators
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