Woke up this morning, checked the blog and wow, lot’s of new hits. Seems like somebody posted the blog to another website called Dangerous Prototypes. That kicked the stats up significantly for the day. The only error I found in the article is that it stated no code is currently available. If you go to the Google code repository, you can find about 150 different files with the code in them. These vary from the C files, to project files, to actual S-Record files that can and have been downloaded onto running hardware. I posted the schematics in 1000.pdf, but I never posted the Gerbers to actually build the board. The reason for that is I wanted to get more of the board testing done. Currently the solenoid driver, input driver, and RS232 interface boards are completely tested. The LED driver has not been tested, but I’ve used the same design on the EEPROM project so I’m pretty sure it is going to work. (I actually stole the chips that I was going to use to make Disaster to make the original EEPROM burner so that we could get Mark’s Flash up and running.) The main microcontroller board definitely has some issues which I know what they are, but now I’m thinking about not using that board at all so it doesn’t matter. (You need some pullups on the debug bus to get the processor to boot without a debugger attached. Simple fix, but annoying none the less.) The last board not tested is the bridge rectifier/power board. It is populated, but I haven’t bothered using the Variac to test it. I’m not happy about the amount of current I can get using the TL783, so I’m thinking about converting my design to a boost converter. The added benefit is I could use a standard PC power supply and step it from 12V to 48V DC or whatever the highest “safe” voltage for CE marking. (I don’t care about a CE mark, I just like to use their safety standards because I dislike being hit by high voltage electric.) That would allow me to use the same design internationally. (Why would somebody from Europe want one of my machines? Who knows? I’m currently amazed that I’m as far as I am on this design and the number of people from Europe that check out the blog.)
So I’ve been pondering playfield surfaces. I have clear coated machines and been really happy with the outcome. Of course, it takes an average of 4 or 5 months to clear coat a playfield, so that process seems unusable. The second thing is that it costs me about $20 for the Varathane that I used. I know that if I started using an automotive finish, it would be cheaper, but I don’t have the work area or equipment to do that. This got me to thinking about using acrylic to cover the playfield. Acrylic is supposedly more scratch resistant than Lexan (polycarbonate) which is the most important feature. Acrylic can also be repolished to get rid of scratches if necessary. So I’m thinking the playfield sandwich would be a layer of acrylic on the top (1/16 inch), the graphics/art layer sitting on a 2nd layer of acylic, and then a thick layer of plywood. Insets would be formed by using a CNC machine to get rid of the plywood. This would allow LEDs to be mounted below, and would make sure that insets would never sink/rise out of the playfield. Every restoration I’ve done, the first annoying thing is to reset all the insets properly. This would make the playfield incredibly fast so I might need to tone down the solenoids a little bit. Not a problem since I can configure them on a per solenoid basis. The cost of a piece of acrylic (24″x48″ is $25.00) Two sheets plus the plywood plus the art hopefully comes in under my $100 target price for that section of stuff. It also means I don’t need to pay for insets and gets rid of a lot of the assembly headaches. I might be able to get rid of the second layer of acrylic, but I’m not sure what I would apply the playfield “translite” on.