Tuesday, May 31, 2011

Changes in the hardware

I've been having a secret the last week...

I accidentally fried some components in the Wonderboard while testing it.
If it was due to the reversed polarity of the cabling and lack of protective diodes or simply to weak cables to run the current needed should be left unsaid.

It also turned out the MOSFET got so hot simply because they were not saturated fully fast enough since the Arduino "only" has +5VDC@0.04A. The specs are around +10-20VDC@0.08A to trigger it, I learned after reading the spec sheet a little more carefully. This created a slow accelerating "puuuuuull" instead of an instant "PULL!". Doh...

Anywho -
I decided against repairing the board and ordered myself a couple of power driver kit's and a relay board from Sparkfun along with a MP3 board so I can get started with the sounds. These are professionally designed and all I need to do is to solder 'em up.

The soldering of the power boards went quick and well and they seem to function properly. Hopefully they'll handle the current needed. This kind of put me at a crossroad, should I -

A) Use relays to drive the flipper coils with the buttons directly and the power boards for the rest.

The obvious benefit would be to keep the high power flipper coils separated from the relatively small circuit paths of the power boards.

The drawback would the staggering 15ms time it takes to trigger...
Also I need to get more relays.

B) Use the power driver boards for all solenoids (but probably only one high power coil per board), and the relay to enable/disable current to the boards.

The benefit would be cleaner cabling and faster triggering of the solenoids, which is crucial for the flippers.

The drawbacks are the relays themselves - I don't know if they can handle up to +48VDC@7.6A...

The main reason for my doubts are the lack of details around +48VDC usage. The specs only show an example for +28VDC@20A... I do know they work with +48 VDC (I had to test it...Curious George ) but I don't know how much current they can handle at that kind of voltage and for how long. I did test it briefly by triggering the slingshot solenoids and it worked as a charm!

As for the MP3 board...
...Sadly Sparkfun had a stock error on their site so it turned out they had to backorder it. But it's shipped now but has not yet arrived. Will let you know how it performs as soon as I get it!

Monday, May 23, 2011

Bumpers and Flippers

Yesterday I installed the slingshot-, bumper- and flipper solenoids. Not currently wired up, but at least they're installed now! Nevermind the sloppy woodwork, this is basically a dummy board to get the alignments correct and to testdrive the design. I expect to do at least one revision before the board will be finalized.

I'm currently planning for light installation and the routing of the cables, but since this is a prototype board I won't install any lighting yet.

Here's a couple of pictures for the craving:
1) Slingshot, nevermind the woodwork....

2) Pop/Jet bumpers. They were tricky to install!

3) Flippers! 

Monday, May 16, 2011

Theme's selected!

I've begun the graphical design now, based on a theme that I hold very dearly. It will be absolutely awesome and as the idea came to my mind it became totally obvious that this was going to be IT.
Unfortunately I cannot tell you any details until I've come further in the design, don't want anyone to beat me to the punch!

Some of you might recognize the graphics, but you'd probably need to be hardcore for that at this stage...

Hopefully the copyright holders will forgive me for doing a mild boundry-breach, but I'll make sure to give them proper credits!

Thursday, May 5, 2011

Switches, Solenoids and Light Emitting Diodes

Yesterday I finished the switch-board that I'm almost completely satisfied with.

The only downside is the connection type for the switches that I've chosen, a simple 'plug & play' solution would be nice but the current version has screws that hold each cable. Not the biggest concern, since I can easily put better connectors onto the cables themselves.

I've put diagnostics LED's on each connection so that I can clearly see when a switch triggers. Should come in handy during the playfield and ruleset testing! All in all, the switchboard has 32 inputs - not sure if that will be enough for the final version, but it should take me a long way. Although not shown in the picture, the dark side of using experiment boards is evident, since each input had to get the ground, power and control connections wired. It's a mess, really. There's around 352 solder points in this design... I'm really happy I bought that soldering station!

I've also attached diagnostics LED's to the solenoid board as well. It immediately showed that "Solenoid 5" was active all the time. After a little troubleshooting I realized that Arduino's serial2 used the same pin so I had to disable it.

I've also put little rubber feet on all boards so that they are elevated a bit from the surface and also get a little more protected from vibrations and shocks. The ribbon/flat cable design I've chosen showed to be extremely nice when debugging, as the board constantly moves from the cabinet to the workbench! I'll probably do this on the solenoid board as well in the future.