Rotating monitor construction *Project finished*

[csa3d]

When are one of you going to start building these for the rest of us transistor-impaired folks?

A few months back I put out a feeler to see if anyone was interested in having a few of these made, and there wasnt really any interest. 
See this post:

http://forum.arcadecontrols.com/index.php?topic=63216.msg632075#msg632075

If there is any interest now, this could still be done.  A few bucks could be shaved off by not including terminal strips, db25 sockets or parallel cables, just let me know.

I am very interested; however everything I'm reading warns to not attempt anything without an understanding... and I'm still trying to absorb and understand the workings and application of these devices and motors and their relationships to monitors and arcade cabs. It's a bit overwhelming to a complete novice...

Not to mention, there are portions of this stuff which require you to alter the design based on the specifics of your motor.  These are the parts which are most confusing to me, and make me wish there was an "all in one" solution for this.  Building and soldering, sure.. i'd give that a go.  But know what I'm doing, not so sure. 

With all that, you guys are still providing way more useful info than any I've seen on the board about this topic, please continue with notes even if us slowpokes aren't keeping up

-csa

[DaOld Man]

Well, my original relay circuit would pretty much cover all motors.
If you used 15 amp relays, the motor could draw up to 15 amps.
My advice to the novice:
Get your motor first.
Go to the junkyard, check ebay, whatever it takes. A window motor would probably work, as would a windshield wiper motor, and I am pretty sure a headlight motor off a 88 firebird will work. (Least I hope so).
A motor with a gearbox on it will turn slower, but have more strength. (Might be two pluses.)
After you get your motor, you will need a power supply.
Or you can hook the motor to your car battery.
Use a multimeter that can measure at least 10 amps.
Put it in line with the motor and see how many amps it draws.
Remember that this is no load on the motor, it will draw more when loaded down.
The H drive I built should be good for 4 or five amps.
If your motor draws more than that you will need a different drive. (Or a different motor.)
Also while you are testing the motor, reverse the leads, see if it reverses.
If you use a windshield wiper motor, it may have to be specially handled.
So,
(1) get your motor
(2) get a power supply capable of putting out the amps the motor will draw.
(3) choose your drive.
If anyone wants to try building my relay drive, tell me what relays you are looking at (part # etc) and I will see if I can put together a point to point wiring diagram

[DaOld Man]

Update:
I found another motor in my junk box. I thought this one was a windshield wiper motor, but Im not sure. It has a knob on the motor shaft, so it may have been one I tried to rig for the firebird.
I bought a few motors trying to make one work.
Anyway, my old AT power supply was only putting out 10 Volts, so I dug out another one that puts out the 12 I need.
My "new" motor works good. Its a bit smaller than the first, and it draws about 1.14 amps in one direction, and a little under one amp in the other direction.
The batteries on my camera are dead, so I will try to post a pic later.

[DaOld Man]

Yet another update:
I have a temp probe on my multi-meter.
I measured the temp on the big transistors.
After the motor runs for about 10 mins, temp on Q2 gets to 122 F.
It's mate, Q3, is just a couple degrees cooler.
I know the motor should never run that long at a time in the cabinet, but just in case, I'm wondering if I should install heat sinks?
On my H drive, I have Q1 and Q3 side by side and Q2 and Q4 side by side.
I did this on purpose, because the tab on the transistor is electrically connected to its collector.
If you look on the schematic, the collectors of Q1 and Q3 wire together, as do Q2 and Q4,
so I figured I could bolt a heat sink across the pairs, maybe making it a little easier to install.
If I had placed the transistors any differently, I would have had to use separate heat sinks on each one.
Since I wanted to keep the board as small as possible, I did it this way.
Any comments/suggestions on the heat sinks?

[HaRuMaN]

HS would be overkill.

[DaOld Man]

Thanks, I suppose you are right about the heat sink. But ambient temperature was 68 F at the time I took the temps. Im sure the temp inside the cabinet in summertime will be higher.

Update:
Here is the promised picture of my new (old) motor.
Notice the knob on the end of the motor. Might be handy if something fails, turn knob until monitor is straight. I might be willing to part with one of these motors, but I wont decide which one to keep until I build the monitor support system.
I will post it then, so if you need a motor, keep an eye out.
Second picture is a printer cable I picked up at a yard sale for 50 cents.
I plan to cut the printer end off. The end I am holding will plug into the computer printer port.

[DaOld Man]

Ok, I cut the printer plug off the cable and stripped back the outer jacket. (See first pic).
I then separated the wires, and trimmed each.
I then used my multimeter to "ohm" out each wire. (Second pic)
I wrapped a wire around the black probe, then touched the red lead to each pin of the plug on the other end of the cable. When I had zero resistance, I wrote the wire color down, and the pin number that the wire attaches to. I dont know if there is a standard color scheme for all printer cables. (I couldnt find one on the web). So I suggest you use this same method to identify which wire goes to which pin. The pins are numbered inside the plug (You might need a magnifying glass).
There are 13 pins on top, numbered 1 to 13.
There are 12 pins on the bottom, numbered 14 to 25. Pin 14 is the first in the bottom row, and is located below pins 1 and 2.
This cord has a shield (bare wire). This wire connects to the plug's metal case.
It will not be used in my application. One wire (Black w/ white stripe) connects to pins 18 thru 25.
These pins are all grounds, and need to be connected together to protect against noise, this cable will save me a little work, since it already has the grounds connected together.

[DaOld Man]

I rigged up a test station. (First two photos)
I ran Koz319s program from command prompt and the leds lit as expected.
I could not wire the inputs as Koz319 did his. The inputs on my computer seem to float high, which means they give a high signal when connected to nothing. So I had to "tie" them to ground to bring them down to low.
I connected the inputs to ground through a 470 ohm resistor.
I then had a 330 ohm resistor tied to the output. I touched the 330 ohm resistor to the input to simulate a switch closing.
This works great.
I tried entering a call to Koz319s "rotate.exe" program in GLaunch.
In mame.cfg, I entered a pre command of "C:\(path to the rotate program)\rotate r 10"
Then I entered a post command of "C:\(path to the rotate program)\rotate l 10"
When I ran a game, the red led came on for 10 seconds, or until I touched the resistor leads together (simulating a switch closing). The red led went off and the game started.
It did the same thing for the green led when I quit the game.
This will work great if all your games in mame.cfg are rotated, I am working on a small program that will recognize which game needs to be turned. I think Koz319 is too.
The third picture is the diagram of my test rig.
Dont let this overwhelm you. It is really pretty simple.
Note about my test rig: I use an old Heathkit breadboard I got off ebay. These things are very handy. Radio shack sells small boards without power supplies that are pretty reasonable in price. I recommend you get one, if you want to get into electronics as a hobby. The parts on the right side of the board is a separate experiment Im doing with the nutchip.
Saint: Let me know if I am posting to much stuff on here. I dont want to use up more than my share of your server space.

[DaOld Man]

Just a quick link to an informative site about printer cables and plugs.
It even tells how to make your own.
But the wire color chart does not match the colors in my cable, so I would not go by that if you are hacking an old printer cable like I did. Use the method I used with an ohmmeter (multimeter), or use an led and battery to identify which wire is attached to which pin.

http://www.geocities.com/keinhong/nfpt/ecp_cable.html

[javeryh]

Awesome work DaOld Man!  I wish I could follow in your footsteps... I'm going to give the whole rotating monitor a shot on my next cab but It might take me forever to figure all this stuff out!   I only want to implement it if the rotation is automatic based on the game selected - I've got a lot of reading/learning to do! 

[DaOld Man]

Its really not that hard to follow what I am doing here, except that my drawings are crappy, plus my cam pics are not good at all up close, unless I use very high settings, then the pics are too big to post.
It might help if you know what the symbols I draw mean.
The schematic drawings are just shortcut symbols that make drawing a circuit easier.
Look at the example drawing I attached.
You can see that the top would be a lot easier to draw (freehand anyway, both suck in Paint, but you can copy and paste.)
You just need to learn what the symbols mean.

[DaOld Man]

Sorry I forgot this in my last post:
Thanks for the kind comments javeryh!

Here is a site that has a pretty neat description of schematic symbols:

http://www.aaroncake.net/electronics/schem.htm

Pull the horizontal divider down, then in the box at the top, place your mouse on a symbol, what it is will appear in the box below it.

Im sure there are thousands of websites that can teach you, just google schematic symbols.

But if all you want to do is build a certain circuit, you just need to learn the symbols used in it. Please feel free to ask me anything about any of my drawings.
Im not above making mistakes too, so if some of your experienced guys see a mess-up, please alert me.

[HaRuMaN]

Shouldn't you be using the correct symbol for a resistor then?

Code: [Select]


---/\/\/\----



[DaOld Man]

Resistors are drawn both as a rectangle and the -VVV- drawing you drew.
If I freehand, I usually draw it like you did, but using paint or most any CAD type drawing, it is harder to draw than the rectangle.
But if you look it up, most designers these days use the long rectangle.

I try to label all my parts, such as R1 is resistor 1, which should help to identify it.

[koz319]

I could not wire the inputs as Koz319 did his. The inputs on my computer seem to float high, which means they give a high signal when connected to nothing. So I had to "tie" them to ground to bring them down to low.
I connected the inputs to ground through a 470 ohm resistor.

Doh!  I knew I must have missed something when I put that site together.  I must have spaced when I drew those diagrams, sorry.  Yes, you definitely need to tie the inputs low - I used 4.7k resistors between the input pins and ground.  I must have spaced when I drew those diagrams, sorry.   (At least I mentioned it, sort of, on the what you need page.)  I'll be sure to update that site.

Thanks for pointing that out!


BTW, DaOld Man, if your ISP doesn't supply you with web space, I can set you up with some site space on the server I'm using, just let me know.


Koz
 

[DaOld Man]

Thanks Koz319.
How does everyone feel about making this topic a website?
I am just getting started. I still need to do the monitor mechanics.
(I will probably copy what you did Koz319, as close as I can anyway.)
This thread could get extremely long over time.

I liked your drawings, they are simple and to the point.
I didnt see the part about the pull down resistors, but I have a bad habit of skimming over the type if there is eye candy to look at.

[csa3d]

As I have shared interest in this topic, I'm definitely excited about all the forward progress, including someone in the software forum getting started on a MALA plug-in for motor rotation.  Keep it up, and let me know if I can ever help with anything.

I do however, think that if you guys decide to take this into a website format, you should see if Saint won't host the images or something, so the information never vanishes.

-csa

*edit*  The Mala plugin refered to earlier is this one by Ede for clarification

[javeryh]

As I have shared interest in this topic, I'm definitely excited about all the forward progress, including someone in the software forum getting started on a MALA plug-in for motor rotation.  Keep it up, and let me know if I can ever help with anything.

I do however, think that if you guys decide to take this into a website format, you should see if Saint won't host the images or something, so the information never vanishes.

-csa

I totally agree.  I'm probably a few weeks (months?) away from attempting this but when I do I plan to document it as sort of a "Monitor Rotation for Dummies" or something... 

[DaOld Man]

I was just killing some time scanning ebay, and came across this firebird headlight motor:

Clicky here

EDIT: The above link is no longer available on Ebay. Just search for firebird headlamp motor.
06/29/09

not a bad deal for 21 shucks (inc shipping).
It looks like the first one I have.
There are several of these motors on ebay, if someone needs one for their rotate project.
Just search for "headlight motor".

[ratzz]

Good work on this DaOld Man.

I really wish that I could attempt something like this, but I am so scared of the back of monitors / tv's, and the associated danger of death that I don't think that I ever will.

Good luck though -- its got to be THE coolest cab modification ever! 

[DaOld Man]

Thanks Ratzz..

Have you thought about doing a rotate with the monitor in its case?
On "The Rage", the 19" monitor I used had recessed buttons on the front, so I mounted the monitor in it's case.
Below is a couple of pics.
Just yesterday I helped my son move The Rage from his bachelor's house to his and his wife's rental house. We wound up having to transport it on its back, and the monitor didnt shift or come loose at all.
Here is a link to the blog I did on the construction:
http://skennys-arcade.blogspot.com/

Edited to remove the pictures, to cut down on this thread a little. If you are interested in seeing several pictures of The Rage, just follow the above link.

[ratzz]

Hi DaOld Man,

I am very familiar with 'The Rage' having been a fan of the marquee you did.

My current project is a 80% cab and will really struggle for space, I think, for a rotating monitor, but it has to be the way forward for true arcade authenticity.

I'll be following the thread with interest!   

[DaOld Man]

Yes, I remember your positive comments about the marquee now..
Do you have a thread started on your progress on the arcade you are doing?
BTW, I removed the two pics in the previous post to cut down the size of this thread a little.

[DaOld Man]

Project update:
I am now throwing together the diagrams to build an isolator board, that will go between the computer and the H Drive.
I dont have a warm fuzzy feeling about interfacing my computer to the H Drive, so I plan to use opto isolators to separate the computer signals from the H Drive.
What is an opto isolator, you may ask?
It is a very small integrated circuit, (also called a "chip") that contains an led and a photo switch. (transistor)
You put power into the chip that lights the LED, then the led turns on the photo transistor.
The transistor is like a switch, that will turn on the H Drive. The computer power and the H drive power are completely separated.
Learn more about it here:
Wiki Clicky

I also plan to add a "auto/manual" switch so I can move the monitor with two pushbuttons, if the need arises.
I will need 6 opto isolators total.
(1) Rotate left (from computer)
(2) Rotate right (from computer)
(3) Monitor on (from computer)
(4) monitor degauss (from computer)
(5) CW limit switch (to computer)
(6) CCW limit switch (to computer)

Im hoping I wont need the degauss, but Im throwing that in, just in case.
*More crappy paint drawings coming soon*

[koz319]

Im hoping I wont need the degauss, but Im throwing that in, just in case.

If it's a CRT monitor, I would be very surprised if you didn't need the degauss circuit - if you want to check, just fire up whatever monitor you want to use, then turn it on its side.  If the colors go funky, you will need to degauss.

On another note, I wrote a quick plugin for MALA that will automatically control the lport based on whatever game you launch.  It uses the same pinout I described on my site, and a default rotate timeout of 5 seconds and a degauss of 3 seconds.  I'll add some config options so this can be adjusted, but if you want to check it out, I have attached it here.   Just unzip and copy to the 'plugins' folder of MALA.

I'm almost done with another cmd line prg that should be able to be used transparently with pretty much any front end, when its done I'll post it, and all the source for this stuff.

Looking at your idea for opto-isolators,  you can probably get away with not opto-isolating the inputs for the limit switches, since you are already isolating the output from the lpt port to the h-bridge.  This is the same signal used to trigger when the limit is reached, so its already isolated.   If you use an SSR for monitor power, it's isolated by default.   Then again, you can get multichannel isolators dirt cheap so what the heck.

For the MALA plugin, add the -autorol option to the 'Mame Config -> Basics -> command line ' field.
Also, put a check in the 'Rotate MaLa with Mame after quitting game if needed' box under 'Mame Config -> Options'

You will need to have installed the DLportIO driver from my site.

Anyway, here's the MALA plugin. (version double beta .1 )

Hope any of this helps,

Koz

[DaOld Man]

Thanks Koz319, the plug in works great with mala.
I use GLaunch, so Im really never figured out how to set up mala correctly.
the gmes I either dont have or dont run right still show up on the menu, plus I cant get a snapshot to display.
Looks like I need to study up a bit.
On my test rig, the red led comes on when I select galaga88, but the display dosent turn, Im sure there is a setting in mala I dont have right.
But I notice the green led doesnt come on after I exit galaga88.
As for the optos on the inputs, I think I will go with them.
I'm hoping the  opto ill be able to switch a relay I already have on hand.
Also Im hoping the monitor I have will degauss when it is powered on.

[koz319]

On my test rig, the red led comes on when I select galaga88, but the display dosent turn, Im sure there is a setting in mala I dont have right.
But I notice the green led doesnt come on after I exit galaga88.

When you say the display doesn't turn, do you mean the monitor rotates but the graphics don't?  If that is the case, you just need to add the -autorol parameter.

(For the MALA plugin, in the Mala options, add '-autorol' to the 'Mame Config -> Basics -> Command Line ' field. Also, put a check in the 'Rotate MaLa with Mame after quitting game if needed' box under 'Mame Config -> Options')

The plugin in it's current form only rotates when a game is launched.  It takes advantage of the fact that when a game exits, MaLa can change its layout orientation to horizontal or vertical based on the game you just played.

Koz

[DaOld Man]

Yes, I meant the display graphics doesnt rotate on the screen.
I dont have the monitor set up yet to physically rotate, plus Im doing this on my desktop PC right now.
But I was observing the leds on my test rig.
They come on when the screen is supposed to rotate.
I will play around with the mala options.
This is very exciting.. Im learning as much as anyone else in here, I think..

[DaOld Man]

Ok, Im going to show my ignorance here..

How do you get to this:

(For the MALA plugin, in the Mala options, add '-autorol' to the 'Mame Config -> Basics -> Command Line ' field. Also, put a check in the 'Rotate MaLa with Mame after quitting game if needed' box under 'Mame Config -> Options')


I cannot find the Mala options you mention.

[DaOld Man]

I figured it out.. Just had to find out how to get back to the options window..
Right click on the mala screen..
I now remember discussing this with someone some time back (maybe Loadman?)..
I guess it was so long ago that I had forgotten it. (Could have been last week  )
Anyway, your plug in works great..
I will be changing my frontend from GLaunch to Mala.. (Has Hell froze over already?)

[DaOld Man]

Ok, I have my computer interface plan. You can hook the Hdrive to the limits and computer just like Koz319 did his, but I am just a little scared that my computer might get harmed if something shorts or the H drives power supply goes berserk.
So I am going to isolate my computer from the rotate circuit with opto-isolators.
The opto-isolator is a very small DIP IC (chip), that has a led and a photo transistor.
It's easier for me to just think of it as a SPST normally open electronic switch.
Put current in one side, and the other side closes.
They have many applications, but the switch side can only handle a small amount of current, so the best applications are computer or electronics.
Ok, back to my circuit.
Attached is my drawing.
I bought a handfull of the Texas Instruments TIL119 optos off ebay. Hopefully they will work for me. I used the specs for this chip to get my resistor values. If you use a different chip, it may require different resistors for the LED side.
The left side of the print is going to the computer. The right side to the H Drives inputs, and 12 Volts DC. The opto-isolators split the drawing down the middle.

Ok, if the computer gives a signal to rotate ClockWise (CW), pin 2 of the printer plug (P-Plug) goes high.

Current flows from P-Plug ground (pins 18-25), through u1 LED, through R1 to pin 2.
u1 output then closes, current flows from H Drive input A through CWLS, through u1, back to + 12 VDC. The motor turns Clockwise until CWLS is reached.

When CWLS switches, the NC contact opens, and NO contact closes. This stops the motor by breaking the current flow through H Drive A.


But now the current flows from - 12 V through R7, through u2 LED, through CWLS, through u1, back to +12V.

This turns on the output of u2,  current flows from pin12 through R2 back to P-Plug pin2, which is still high.

Pin 12 of P-plug is the input that tells computer that clockwise rotation end has been reached.
This pin is held LOW by R3 connecting it to P-Plug ground.
But when u2 is turned on, Pin 12 goes high.
Since R2 is a lot smaller value than R3, current flows from pin12 when u2 is on.

The same thing happens when the computer issues a rotate counter-clockwise command.
Pin 3 goes high, which turns on u3, which turns on H Drive B, which rotates motor counter clockwise.
When CCWLS is activated, u4 is turned on, which brings P-Plug pin 13 high.

I dont have the monitor on/off interface drawn here. I may use a solid state relay for that, which will elimanate the need for another opto-isolator. (Like Koz319 suggests).

I have seen a problem with using the printer port in this application.
On my test rig, when I turn on my computer, before Windows starts to load, all outputs from P_plug go high for about 1 second.
Then again, when Windows is loading, they all go high for about 3 seconds.
Im thinking that this is going to rotate the monitor off which ever limit switch is made.
This could mean a crooked monitor angle when ever the machine is turned on.
It will straighten when you play a game that issues a rotate command, but still, it may be embarrassing when you first power up your arcade with a bunch of friends watching.

So, we need to either come up with a way to disable all outputs if all are turned on,
or use another output as a disable, if it's on, then no drive outputs, or have a power on time delay.
Say, kill motor rotation until 10 seconds after computer is turned on.

This problem may be with my computer only, I need to test it on a few others I have.

Edited: Found a flaw in my first drawing. This drawing SHOULD be ok..

[DaOld Man]

I threw together a quick diagram of how the printer cord, interface board, the H drive, the power supply, and the limit switches will connect to each other.
This drawing is extremely crappy, but it was drawn in a hurry.
maybe later, after I get everything built, I can post some real pictures.
In this drawing I am using Happ pushbuttons as the CWL and CCWL switches.
This is what Koz319 is using, and I think it should be readily available to everyone, so why not use them?
Please dont laugh at the way I drew them, well, OK, go ahead and laugh....
 

[csa3d]

I bought a handfull of the Texas Instruments TIL119 optos off ebay. Hopefully they will work for me. I used the specs for this chip to get my resistor values. If you use a different chip, it may require different resistors for the LED side.

For us dummies.. I assume there is a math formula in the event we can't find these same chips?  Can you share if so?

Thanks again for your updates, and your drawings are great so far!  I'm just amazed you are using Paint for anything.
-csa

[DaOld Man]

Thanks CSA3D..
Yes, I really do need to loose the paint program..

I had a very long post typed out about how I figured for the resistors in my circuit, but I guess I timed out and it wouldnt let me post.
Note to self: Always copy the text before posting, so you can paste in new post, if necessary.

Anyway, I dont really want to retype it all, so i am going to make it short.

To get the resistance needed for the optos led, it is basically the same as with any led.

First you need to know the supply voltage, in my case it is two voltages, computer volts of 5 and H Drive power supply of 12.

Now you need to know the voltage drop across the led and the minimum current needed to light the led, and the maximum current that the led will handle before it destructs.
You can get this information from datasheets. Just search the net for a datasheet for the device you are using.

After you have this info, just use Ohms law.
E/I = R
or Volts (E) divided by current (I) equals resistance (R)
Current is amps. (1 milliamp = .001 amp)
Resistance is in ohms.

So, on my computer side, I subtract the volt drop on the led (from datasheet) from the 5 volts, or 5-1.5=3.5 (datasheet says volt drop on my optos is 1.5)

I then figure the current I want. (also min from datasheet).
Since the computer port can probably only supply up to 20 or 25 milliamp, I figure for 10 milliamp (ma), to be on the safe side.

So E/I=R or 3.5/.010 = 350 ohms. I had some 330 ohms, which figures to be .0107 amp, so they should work fine. (.0107 amp = 10.7 ma)

For 12 volts, I used 12-1.5=10.5
So I figured the resistance for that side the same as above, but using 10.5 for E instead of 3.5.
I usually dont have the exact resistor on hand, but you can usually go up or down a little.

I plan to test these optos on my breadboard when they come in. I may have to adjust the values of the resistors.

To figure for the transistor side of the opto, you need to know the transistors IF (Forwarding current) and IMax (maximum current).
These should be on the datasheet.
Using the above formula, you figure what you need to get the IF and not overload the transistor or the power supply.

If you would like me to figure all this for you, just give me the number of the device you are thinking of using, I will be glad to figure what you need.
But it aint rocket science. Im sure you can do it.

[bfauska]

I remember reading in the past about the pins of a parallel port doing various things on boot.  I don't remember what the application was, I think it was a masking system for a home theater screen or something.  Anyway, my point is that I think it applies to enough computers that people should plan on working around it somehow.  I think the delay on boot for that circuit would be the best bet, you could run the delay fairly long if you wanted to be safe, the monitor shouldn't have to rotate until you are in the menu and choose a game right?  I haven't looked too close at your schematic, but I imagine you could drop a time delay relay into the power supply for your motor control circuit.  Trigger the relay from the 5v or 12v in your computer and your good to go.

[DaOld Man]

Thanks Bfauska.
I have been thinking about this tonight. I thought maybe a transistor, capacitor and resistor set up as an "on delay timer" (On delay timer would pass current to the interface after a time delay, say 30 seconds after power on, hence on delay).

But for this application, since all outputs are turning on at once during boot up, I thought the simplest approach would be one transistor and one resistor.

Look at the attached print.
I added a PNP transistor right below the printer plug.
I tied the base of this transistor through a 470 ohm resistor to pin 6, which is the fifth output. Since we wont be using the fifth output in our project, I thought this would work. I added it to my test breadboard circuit and it does work.
Here's how:

On computer bootup, all output pins go high.
A PNP transistor passes current from its Collector (C) to its Emitter (E), only when current flows from its Base (B) to its Emitter. (In other words, the base has to be negative or ground).
So when all outputs are on, pin 6 is high, or positive. No current flows from base to emitter, so no current flows from collector to emitter, so, the LEDs do not light.
But when pin 6 is turned off (Low or negative), current flow from base to emitter, so current flows from collector to emitter, powering the LEDs.
In short, if pin 6 is turned on, the leds are turned off.

This works on my test bread board, so I am going to implement it into my interface circuit.
Now, this method will not work on applications that require pin 6 to be turned on when pins 2 or 3 are on. But we dont need pin 6 in our project, so we should be good to go.

I used the 470 ohm resistor to limit current flow through the transistor. transistors have a maximum current flow before they self destruct. I first tried a 4900 ohm resistor, but the leds seemed pretty dim, so I tried the 470 ohm, and they look good.

Please note that I adhere to the principal that current flows from negative to positive, some folks will highly disagree. If you buy into the positive to negative theory, just reverse the current flow in your mind, and it should be A-Ok..

[theCoder]

Man, this is good stuff.  I love the way you got past the boot issue with just 2 components.  I would have been tempted to do something with a 555 or PIC.  Those opto's are great to work with.  Simple & safe. 

Make sure to post a short video when you have it all integrated and working.

[DaOld Man]

Thanks theCoder!
I will try a video, I havent done that before, so it might be even crappier than my paint pictures, but we shall see..
I had to make a change on the circuit.
I double checked Koz319s website, and I see he is using pin 6 for the degauss circuit, so Im moving my pnp transistor from pin 6 to pin 4.
Hopefully I wont need the degauss circuit, Im hoping the monitor will degauss when it turns on (man, I need to test that!). I intend to turn the monitor off while rotating.
But I need to leave that output alone, just in case someone else wants to use it for degauss.
The next drawing of the interface I post will have the change on it.

[koz319]

In regards to the parallel port pins going high on startup,   I did not implement any type of bypass on my cab, it's just the h-bridge straight to the parallel port. 

 For my particular set-up, the only negative has been the degauss circuit being repeatedly activated at boot.   The degauss coil in the monitor has thermal protection built in, so it can only be activated every so often (say 30 seconds or so).  If it is triggered at boot (which happens on occasion), and then I go straight into a game which requires the monitor to rotate, the thermal protection on the degauss coil keeps it from degaussing completely when rotation is finished, and the colors are off a little.  I't falls into the occasional annoyance category. 

I actually want to do pretty much the same thing as DaOld Man drew up and just haven't gotten to it. (probably because it will take me about 40 minutes to clear out a space and  move the cab out from the wall so I can open it up to implement a 2 minute fix )

I would definitely recommend implementing this from the get go.   

Gotta go, looks like theres a woot-off going on!


Koz

[bfauska]

Turning off the monitor would certainly be a clean solution, but if you want to draw focus to the cool rotating monitor in your setup, could you have the front end play an animation while the monitor rotates before a game starts?  Like a spinning spiral, or a bunch of gears that look like they are doing the work.  The sign at the Wynn in Las Vegas has a part that moves over a huge monitor and when the movement is happening they have all kinds of animations that play with the movement to interact, it looks really cool.