Mike's Project Tracker

Here is my schematic so far for my solenoid driver board.  The PWM control took up too much space to include on the board due to the limitations of EagleCad's freeware.  Each control circuit has two inputs, one for the trigger and one for the PWM power control.  I might add in a way to disable the single pulse generator so that you can just trigger it on or off if there is room on the board.  However, I can only think of a few instances that would require it as most solenoids will burn out if left on too long.  I will post the EagleCad files including the board layout when I am finished.

Now that I have been lazy about working on my pinball machine for a while, I got mad enough to motivate myself to work on it.  The solenoid driver board is being re-hashed, again but in the meantime I am trying to put together a 6-channel audio mixer and stereo amp. Just quickly, to update on the solenoid driver board I've been working on the schematics for it.  I am at least doing a better job of documenting my work.  I will be posting the schematics and my first board layout soon.  Due to the board sized limitation on EagleCad freeware , I can only fit (at least I think I can) the circuitry to drive six solenoids.  I am fine by this.  It makes my solenoid power distribution more modular.  I will likely use three boards for 18 solenoids.  The EagleCad freeware is limited to a board size of 8 x 10 cm.  I could have used KiCad as it is unlimited but from what I have heard it is not as user friendly and everyone has EagleCad which makes shar...

I purchased a little while ago the worst pinball machine playfield ever: Williams' Hardbody .  It is considered to be one of the worst pinball machines ever made and that's why it was cheap!  I'm scavenging usable parts from it.  Drop targets, raised ramps, ball savers, you get a little bit of everything from the playfield.  I also got Laser Ball , an average pinball playfield. Bally HardBody Williams Laser Ball  This is by far and away the cheapest way to get parts.  I paid $200 for both playfields and considering that even used pop bumpers can cost $30 so it was well worth it.  I'll likely have a ton of parts left over from my project in the future but if anyone wants to buy an unpopulated playfield let me know. The Laser Ball playfield is actually in good condition but is just rather dirty from being stored for so long.  I've also kept the non-broken plastics. 

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...