Last week was spent moving pinball machines from VT to MA, and doing some ordering for Disaster. I bought a bunch of cheap 48V power supplies off ebay. They are low current but should be good for testing the solenoid driver card at 48V instead of the 5V/12V that I used for the initial testing.
I bought a PC power supply that is beefy enough to be used for a boost converter from 12V to 48V. I’m pretty certain that I’m going to power most of the low voltage solenoids/lighting/motors with a PC power supply. They are inexpensive and ubiquitous. The one question that I have is should use the PC power supply and a boost converter to switch the 12V supply up to 48V.
My current guess is that I need approximately 15A at 48V to power the high power solenoids. The 15A is complete conjecture on my part, and I won’t really know what the real requirements are until I take some current measurements using an oscilloscope. (Tried to win a free oscilloscope at work today and failed. Guess I have to continue to scour ebay looking for a good deal.)
There are currently two different designs for the 48V source. The first design using the 12V supply from the PC power supply and then a boost converter to up the voltage to 48V. One difficulty in the design is that an inductor with a very high saturation current is needed. (about 100A). The second design would use a simple full bridge and smoothing capacitor to convert the AC into DC, and then a P channel FET driven by a microcontroller to act as a voltage voltage regulator. Best case would be finding an inexpensive 48V power supply, but I haven’t located that yet.
I bought a couple pieces of acrylic to act as a playfield surface. I bought a small piece to make the mini-pinball machine which will prove out the driver, input and lighting cards. The second piece of acrylic is for the Disaster playfield. I have to go through my extra parts box and see how many things I’m missing to make the mini-pinball playfield.
Last thing is the new Taxi machine. To say it doesn’t work is an understatement. At this point it doesn’t boot. I need it to be up and running by Thanksgiving. I just ordered a bunch of basic soldering supplies, supplies for surface mount, and a bunch of general things. Most of this stuff Mark had in his basement, and we just used his supply. (While Pb may be a big no, no in new electronics, it still reigns supreme in the Taxi machine.) I bought a good amount of lead solder for re-wetting connectors, etc.
Since so many things are not working on it (i.e. not booting), I need to visually inspect the whole machine and see what is the problem. Just a quick look last night was Q73 and Q75 were toasted. One of the pop bumpers is seized. One of the kickers switches was always closed. Guess it’s time to start with testing all the voltages.