Sunday, June 26, 2011

Oh, those legs!

Got tired of bending myself into unnatural positions when I was working on the pinball machine so I attached the legs. A bit prematurely, since I need to take them off again any time soon to sand+paint the cabinet...

But it's starting to look quite good, doesn't it?

1) Cabinet with legs attached. Note the fancy global illumination lamp on top of the cabinet...

Tuesday, June 21, 2011

Dot Matrix Display

This should come in handy when the time comes....
Interfacing a real pinball DMD with Arduino.

And another about making DMD friendly graphics...
DMD Graphics with Flash.

More pinball projects!

Just found out a couple of days ago that the Longhorn Engineer is also building a pinball machine. He's come a bit further in his building than I, so check it out at

There's also Ed's Junk, who's creating a pinball machine based on the old NBA Hangtime games.
Be sure to check out Ben Heck's pinball project as well at
And in case you missed it, Jeri Ellsworth is (was?) building a machine as well as other high-tech stuff I wouldn't dare trying to understand!

I'm pretty sure there's a lot more out that, let me know if you got a project going on - I would love to know about it. It always nice to see others honoring the past and show that pinball is just as great today as it ever was.


Sunday, June 19, 2011

Mixed feelings...

Got the two MP3 Triggers playing alongside nicely now, complete with stereo sound mixing independently from each other through the same speaker set. The circuit was almost insultingly easy to create but it took a little trial and error...

I got confused about GND and GBUF, and since I burned the first cheap amp I wasn't to keen on testing further. So a little research later, I bought a new cheap amp and soldered a couple of resistors here and there - and it just worked!

This is enough volume to keep it interesting for now, but I'll probably have to get a better amp later on.
For those who are interested, this page contains the circuit needed. Simple, eh?

I also got receiving status requests from the MP3 Triggers to work at 19200 baud using NewSoftSerial (now: SoftwareSerial). Couldn't get receiving to work at all at first, but I needed to get the latest beta-driver along with a couple of specific pins on the Arduino Mega2560 to get it running.

The timing got off sometimes causing the response to get lost somewhere in cyberspace, but that was rectified using a stand alone power-supply instead of the USB-only that I was using when testing. Wish I knew that a couple of hours earlier....

Still can't get multiple SoftwareSerials to recieve properly thou...

Advice are appreciated!

Wednesday, June 15, 2011

More cabinet work laid to rest!

Spent a few days mounting the coindoor, siderails and various other pieces on the cabinet. Starting to actually look like a pinball machine now!

1) Top view, start button, coindoor, plunger, skirt and working single ball feeding system.
It needs additional components to support multiple balls, which the final board will have.

2) Inside view of the coindoor, which will eventually take Swedish 5-kronor or simply any coin.
Also, the lever guide assembly which locks the lockdown bar can be seen at the top left. 

3) The mess. Everything looked so neat and tidy before
the big (BIG) power cables took over the place.
I also spent some time beginning on a wire harness, so now all solenoids are plug&play connected to the machine. Of course, once I find a decent solution for having the board in a vertical position while doing work on it, I will fix the wire harness to the board itself. Right now it's a bit messy.

I still fear the day when I need to unscrew EVERYTHING, clean it up, paint it and reassemble it again.

But it will be awesome!

Tuesday, June 7, 2011


Yes! Got software serial working with the MP3 Trigger v2.

Once again, it turns out I didn't read carefully enough...
First - the ini file must be named MP3TRIGR.INI, not mp3trigr.ini etc.
Second - The baud settings in the file needs to be "#BAUD 9600" and in my world the hash-mark is a comment, so I removed it to enable that feature.... I thought.
Third - The SoftwareSerial library differs from the original, since Write (send bytes) and Print (send characters) are two different functions in the hardware version, but one and the same in the software. I needed to add the output type as well to get it working.

But after a bit of reading and fumbling around I can now use the pins I want for communication.

Hopefully 9600 baud is fast enough to trigger the sounds during a running game.

Monday, June 6, 2011

A little reconstruction here, a little reconstruction there...

... and we got sound!

Well, at least sound from one unit. The other one hasn't been ordered yet.

I had quite a struggle getting stuff to work and selecting the correct serial settings for the MP3 Trigger v2. The problem began with the first serial port occupied by one of the power boards connections. I.e trigger a sound - trigger the solenoid. Not good.

I tried resorting to using software serial communication instead...

...but after a long troubleshooting it turns out that the baud setting was not changeable in the ini file as I believed it would be. Since the baud is fixed at 9600 for software communication I couldn't use the SoftwareSerial library for Arduino to create a custom pin for serial communication. But it worked itself out alright in the end since the Mega2560 has three additional hardware serial ports that I could use instead. 

To get more than line-out level audio I had to get a small amplifier. I figure for testing purposes, a simple 7$ circuit would suffice, correct? Yes, it did. But I won't wake the neighbors with this! 

1) Cheap audio amplifier. This was gathered from a cheap MP3 speaker set that was mercilessly butchered and brought back to life by the ATX PSU. The next question is how I should mix the two sound boards' output into one stereo channel that can be sent to the speaker set...
I also spent a lot of time rewiring and cleaning up the electrics inside the cabinet. Now I got dedicated connections that I can tap +3.3V, +5V, +12V and +48V out of. Also, I rewired the Arduino and the one (later two) MP3 Trigger I got to use the computer PSU instead of a dedicated PSU for Arduino. 

2) Top: +48VDC connections, fusebox, +12VDC connections
The other top: Switchboard, temporary speakers
Center: +48VDC power boards, ground-bridge, Arduino, sound board, (cheap) audio amplifier
Bottom: +48VDC PSU, PC ATX PSU, +3.3/+5/+12V power connectors, extension cord

More power, cleaner cabling.  I like.

Saturday, June 4, 2011

Milestone 1

There's magic in the air tonight!

First, an incredible day in Malmö with my wonderful girlfriend (who deserves lots of credit for putting up with me building a pinball machine in the living room). We visited an exhibit there about vegan food and had a great meal. Highly recommended!

After that I wired up both flippers and kicked the ball around with the new power boards. Worked absolutely perfect! I accidentally put my knuckles in front of the flippers at one point, so I can guarantee they pack a heavy punch! I also tried the table at approx. 10 degrees angle and there were no problems at all hitting the higher places with force, so my initial design with quite high ramps should be alright.

Now that I know everything works as intended I can focus on getting the reset of the board and functions in place!

Wednesday, June 1, 2011

We're in control!

It turns out me burning the Wonderboard wasn't really my fault. I had a faulty coil so the circuit shorted. Instead of the minimum 4Ω my coil was 0.004Ω....

Ok... I lied. It was my fault also. I need to have normally closed EOS installed, mine was normally open. That also caused the high resistance coil never to trigger and thus burning the coil when I applied the +48VDC current.

This is how it's supposed to look when done (or redone) correctly:

1) The redone flipper assembly. Note the normally closed EOS switch. I've also installed the capacitors now. The nice thing about this setup (the correct way etc) is that if the EOS switch breaks, the resistance of the coil gets locked in high resistance, which means that the coil shouldn't burn out.
2) A closeup of the connectors. I've decided to use 'hot-plugs' so disconnecting the solenoids will be quick and easy if they need repairs. It also makes it impossible to connect power in the wrong direction since the cables will have matching pairs.

I've tested the setup with a regular ATX-powersupply and the new power driver boards and it works like a charm! Will be receiving my ATX-connectors in a day or two so I can supply the driver boards with +48VDC instead... (Wish me luck!)

Also, I got my MP3 trigger today, yeah!
Now I just need to connect a powersource (buy a powerplug 'head' or drive it directly from Arduino's +3.3VDC) and get FAT16 microSD flash card and I'll be playing MP3's like there's no tomorrow!

Can't wait!