Mike's Project Tracker

In my initial solenoid power board design, I used a PWM signal to control the power to the solenoids.  I used an AND gate so that the PWM signal could be constantly running but require the microcontroller's command to turn on.  This is done by putting the other pin on the AND gate to HIGH.  I have added a PWM component to the single pulse generator so that I am able to control the average voltage of the pulse. I am also trying to offload as much work as possible off the microcontroller so that it runs quickly.  For most of the solenoids in the pinball machine, the power that is required will not change during the game.  The only ones that I can think would possible change would be the pop bumpers.  I would like them to be stronger during certain periods of play.  To do this, I think I will need to use a 50V power supply in order to be able to play the game at a lower power level and then to have enough reserve to raise it to a noticeable difference....

While testing out my new test playfield with just the mechanical switches, one of pop bumpers got stuck.  As the pop bumper was stuck, the switch remained closed, and this kept the solenoid powered.  The switch generated a lot of heat melting the pendulum from the pop bumper skirt until it melted.  As it melted it became short enough it could not trigger the switch anymore and finally released.  This is not good.  This is a bit of a safety issue.  What happens when you are playing the game and you do not notice. To solve this problem, I determined I needed a single pulse that would not fire again until the switch had been pressed again.  So even if the switch is held down, the pulse is sent only once.  The lower logic level voltage (5V) will not heat up the switch as it will be current limited by a resistor rather than just the solenoid on 35V. To produce this single pulse I used the following: 74AC08 - AND Gate 74HC14 - Hex Inverting Schm...

All the playfield machinery I have I purchased used online or from online classifieds.  Some components are direly expensive such as the ball trough.  So I decided to try and make one. Makeshift Ball Trough / Ugliest Sheet Metal Work Ever Above is a photo of the ball trough I made.  It is ugly, poor workmanship on the sheet metal and the ball launcher is a little loose; but it works.  I purchased a very cheap sheet metal hand brake to make this and other brackets.  I also made a slingshot mechanism as well. Makeshift Slingshot Mechanism It works.  The only issue with the slingshot mechanism is that I had to thread some 1/4 inch rod.  I used two nuts to lock the far side so that it does loosen during use.  The two nuts take up a lot of space a leave little room for the two microswitches that will detect when a pinball has hit the slingshot.  These are a real pain to make when, honestly, I do not have the right tools for it. ...

What we have here is playfield built wrong.  It is not because it lacks parts, or does not have all the features you want it to have.  It is wrong because it is too thick!  My research has led me astray.  I used your standard 3/4 inch plywood to build the cabinet including my prototype / test playfield.  After I put those pop bumpers on and they did not work consistently, I investigated. Bad Playfield!  The playfield is too thick for pinball components. The pop bumpers under the playfield. The photo above shows the three pop bumpers under the playfield.  The pop bumper is triggered when the pinball hits the pop bumper skirt.  The skirt has a pendulum that sticks down below the playfield and can be moved from its centre resting point to a point on the circumfrence of a circle.  The circle's size depends on the angle that the pendulum is actuated to.  There is a leaf switch with a saucer.  Then the pendulum swings out, t...

I also have some more new toys. I was frustrated with my old El Cheapo soldering iron. The tip was too large, the temperature was not regulated and the tip would just disintergrate through normal use. So I bought a nice 60W American Hakko soldering station. My American Hakko 936 60W Soldering Iron What a world of difference. When buying a soldering iron look for ones with ceramic heaters and that have interchangable tips that have the heater inserted. The difference between spending $30 bucks on a soldering iron to one for $70 (Like this one was, on sale) is well worth the price jump.  If you are even thinking of building electronics, do not both with the cheap ones.  Its just not worth it, buy something like this life saver of a soldering station! Makita Li-Ion Drill / Driver  Another tool that I purchased is a lifesaver as well but it is not a necessity like the soldering station.  I purchased a Makita 18V Li-Ion drill.  It was my birth...

I was getting to the point where I really needed to build on something. I have numerous pinball parts but have nothing to attach them to. I managed to find some pinball plans for a Williams Widebody pinball machine. All the measurements are in mm sadly even though all pinball cabinets are in inches. I converted and change it all to the nearest quarter inch. Well sort of. The guy who measured this was intending on using 45 deg cuts in the corners. My skill saw is too cheap for that so I changed the measurements for butted joints. The interior is set for a 23.5" wide playfield. The length of the cabinet is 51.5" in total. I used 3/4 inch plywood so the bottom would be 50" long for example. You can pretty much dimension the rest from there.  I did get a little chipping of the plywood but I went out and bought a blade with more teeth for finer cuts. It's a 60 tooth saw blade and my skill saw doesn't really have enough power for it so I have...

If you are sick of them at this point, you know how I feel.  I was missing a switch.  That's just shocking.  The only way to turn it off was to unplug it. I had no indicator lights as well.  Guess I was not thinking much about safety when I built it.  Another problem with my power supply was I was using old oil and paper capacitors. They work and I still have them but they take up a lot of space, are not as reliable, and on the whole, my power supply was rather ugly. The new sexy version of my solenoid power supply! Out with the old and in with the new. This is my rebuilt power supply. I grabbed a scrap piece of aluminium from work and got a 90 deg angle put in it. The aluminium will act as a heatsink and also minimize electromagnetic waves emitted by the power supply though this is small because I'm using a toroidal transformer when compared to a conventional transformer. I plan on using some chicken wire I happen to have to make a farada...

My extra room in my condo was getting a little overrun with electronic components. It was time to build a proper workbench instead of littering my computer desk with all sorts of junk. Also, it was an excuse to buy some new tools such as a skill saw. Cheaped out on the skill saw and got a $60 7 1/4 inch saw. Ah, it works. I did purchase a plywood blade, ie. many teeth, to make smooth cuts through plywood.  It made a huge difference compared to the rip blade that came with the saw.  I also have a mastercraft jigsaw I purchased on sale at Canadian Tire for $45 bucks. That's for later though when I need to make odd cuts for the playfield. My workbench covered with... stuff. My trusty new skill saw. Here is my workbench. Evidently I've been using it. I made it myself using 3 2x10's for the top and 2x4's for supports. I used drywall screws because they work and are cheap.  Drywall screws are more brittle than wood screws but for most stuff they...

Now I've shifted my focus to building a I/O board for all the many lights and small devices used on a pinball machine.  In order to reduce the amount of space I would need I opted for Darlington Arrays which are many darlington pairs (remember those?) in a nice DIP package. I am using ULN2003 darlington arrays.  They have 7 outputs and I wished they had 8 outputs then it would line up so nicely with my shift registers.  Unfourtunately, they do not and my arrays and shift registers are staggered.  Initial Testing of the I/O Board controlling some LEDs via a IDE cable from a computer. The I/O board uses shift registers to control all the outputs and darlington arrays to sink the current.  It is important to note that they sink the current and do not drive them.  The 'outputs' of the array are hooked up to the LED which is then hooked up to the positive voltage.  The darlington pairs inside the chip, when turned 'on', allow current to flow t...

Pinball solenoids come with designations like 23-800.  The first number, 23 in this case, represents the American Wire Gauge (AWG) used.  The second number, and the more important number, is the number of windings which is related to its power rating.  A solenoid with less windings, say 400, is more power and is used for such applications as actuating the flippers.  These solenoids get very hot very quickly, which increases the resistance of the solenoid thereby decreasing the current and therefore the power.  To avoid overheating, these high powered solenoids will have two coils.  One for the main actuation of the solenoid, and another to maintain the position.  The second solenoid will have a smaller wire gauge and more windings.  In example, my flipper 'coils' are 15-411, 15 AWG and 411 windings.  They are quite strong and found in some of the latter Williams pinball machines such as the popular Adams Family machine.   You...

This entire time I've been using the PC power supply just by sticking wires in the ATX plug. Not a great solution as the wires have a habit of popping out. To turn on an ATX type power supply you need to short the green and ground (black) wires. ATX powers supplies are the most common type. The only other one I know of are Dell's, which have a special configuration for the 'ATX' plug. Same style of connector, completely different voltages at each pin. This is why your nice new motherboard explodes because you used your old Dell power supply when building a new computer. My friend knows this from personal experience. Lab Power Supply Formerly of PC I have managed to take that old PC power supply and make a proper lab power supply out of it. It's a rather simple setup. You can find out how to do this yourself on http://www.instructables.com/id/ATX--%3E-Lab-Bench-Power-Supply-Conversion/step2/Planning/ and you can find all sorts of other odd do...

I needed another power supply. A quick google search tells me I do not want to pay the kinda of money required for such a high voltage high amperage power supply. New solution discovered! I could build a voltage inverter that gives me -12 V from my extra 12 V line. The max draw on the 12 V lines from the PSU is 380W. That should be enough right? New solution = new problem. The voltage inverter calls for a fast switching mechanism to charge a capacitor with a negative voltage. The problem is that it cannot charge it fast enough. The instantaneous power requirements for these pinball solenoids are too much. So you would get maybe a flipper to work once then wait ages for the capacitor to charge enough for another go. I could have built a massive capacitor bank but that’s impractical, not to mention the extremely slow start up time. There is one solution left to my power issues that does not involve buying a new power supply. That is to build one. For an unregulated power supp...

After finally figuring out those shift registers, my concerns turned towards my power supply needs.  Logic circuits work on either 3.3V or 5V so a PC PSU would be perfect.  On top of that, they are a dime a dozen.   Someone should have a spare one lying around. Formally Functioning PC PSUs Well, someone did have some lying around.  The permanent marker demarkation on the left one says it all.  At least they are useful for parts.  Not satisfied with the quality of my previous procurement, I set out to purchase the cheapest power supply I could find.  I purchased a Coolmax 500W power supply from Canada Computers , who happens to be a fantastic retailer for anything computer related.  I don't really buy from anywhere else anymore.  My control circuit power supply needs are now furfilled.  Unfourtunately, the 12V rails of the PSU do not have enough voltage to actuate the solenoids that are used in 90% of the mechanisms i...

My initial plan to control the pinball machine was so have a computer communicate through a USB link to control all my electronics.  Apparently, that's pretty difficult.  Thankfully, microcontrollers exist.  Microcontrollers are, in essence, programmable chips.  Kind of like a mini-computer that controls the voltages to a number of pins or reads the voltages off those pins.  Start varying voltages and you've got signals. I borrowed a Arduino microcontroller from a friend of mine who happens to be an electronics wizz.  I did a couple basic things with it.  I started with the all important turning on a LED (with a resistor this time!).  Then I used the transistors from my now disassembled electronics kit, to power the LEDs from a power source other than the microcontroller itself as it can only supply so much power.  The Arduino's software is C based which is really close to Java which is the only programming language I learned in class....

I did not do too well in the one basic electronics course I did have in university.  The ability to conceptualize everything physical and how it all interacted with each other served me well... in my drafting class.  When it came to electronics, the one thing that irritated me so much was that all the equations were written for conventional current when the 'flow of electricity' was from positive to negative.  But that's not true!  The flow of the electrons (or electricity) is from negative to positive.  The electrons are repelled by the negative charge of the electromotive force, ie. battery, and are attracted to the positive end through the circuit.  I was ok for DC current because the equations worked, I just had to put negatives in the right place.  When AC current came around, I was hopeless as using negatives in the equations simply did not work.  Now I just imagine it as a hydraulic system instead.  Now it makes much more sense. Giv...

A good question to ask is why would I, someone with no electronics experience, try to build something as maddening as a pinball machine?  In short, sheer boredom.  To give you a little context, I had recently graduated from university as a mechanical engineer.  I was stuck in a IT job with no work to do despite persistent begging on my part.  No, it's not the ideal job just twiddling your thumbs all day and attempting to memorize the entirety of Wikipedia and getting paid for it.  It is incredibly stressful and degrading.  You get stressed out from being expected to be busy by others yet you have nothing to do.  Well, at least you have the perception of that expectation.  Also, you feel worthless because you accomplish nothing.  I'd rather be drowning in work than experience that again.  And I'm in the military so I could not just quit my job and I was highly visible in the workplace.  But, that's all in the past!  I now have ...