I'm sure at the title alone a few of you rolled your eyes before entering this thread. Another guy wanting to build a home machine who is in way over his head. A quick introduction before I state my question(s). I'm a software engineer in Seattle who has over 10 years of experience writing code, hacking and playing the tech guy role. My understanding of EE goes to the bare basics and I'm attempting to fix that by taking on projects that can evolve and get harder as I find better ways to implement things. My twin brother is also a software engineer by trade and his understanding of EE is better than mine but in no way is he an Electrical Engineer.
Together we've decided to take on the task of building a custom pinball machine. We've bought many of the basic parts we need to get started and have read every resource we could get our hands on for how to build a machine. Our goal is to document our progress and keep it open source including youtube videos and blog posts on what we discover along the way. The goal is a new-age pinball machine that uses mechanical parts and is run via Arduino(s) and Raspberry Pi. We've had plenty of success on making the Arduino and Raspberry Pi communicate, play sounds, and do things the game would do after receiving input/events from an actual machine.
Over Thanksgiving weekend we are going to assemble the lower playfield and try to wire a few things up. Mainly I want to hook up the side flipper buttons to the arduino, and the arduino to trigger the actual flipper assembly. Any help or wisdom would be great on the topic so I don't burnout any components while initially hooking them up. Now to the technical specs and my question(s).
Let's imagine I'm hooking up only one flipper at the moment. The flipper is an FL 15-411 and the assemblies EOS switch gets closed at the EOS. I read up on how the flipper should be hooked up from http://stevekulpa.net/pinball/bally_flipper1.htm. Attached to this post are three images. Two of them show the assembly in both open and closed position. The third image is how I think the wiring schematic is suppose to be. My power supply is this: amazon.com link »
From what I understand I should have a power bus (24v for most things, but 48v for the flippers). I'm suppose to hook the power up to the power terminal and then I get a bit confused on the other two terminals. It says EOS goes to the middle terminal and EOS + GND goes to the third terminal. Does this mean one side of the EOS goes to the middle and the other side goes to the last terminal? The next question is what kind of transistor do I need to switch the flipper on and off from the Arduino? I read an interesting article on transistor math and was told I need a transistor for 100v (double what you're planning to run to it) but I'm not sure what amperage it needs to have? The FL 15-411 says its resistance is 4ohms when on the high coil and 145ohms when on high and low coil (holding). So if I'm running 48v through it that's 12 amps or 0.33 amps running through it. My last and final question is do I need a diode between the arduino and the transistor to avoid some sort of blowback? Is there anything else I'm missing? I know this is pretty EE heavy and probably common sense for most people with electrical knowledge so I would love feedback.
And for those of you wondering what the theme of the pinball machine is, it's Spelunky (the console game). Thanks to anyone who takes the time to read this post and especially those who comment.