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Rotating monitor construction *Project finished*
DaOld Man:
Thanks Koz319..
I found that the pin 4 was staying on after bootup, which kills the leds, so I tried the same hooked to pin 7, but had the same thing on bootup.
After much head scratching, I found that if I "broke the ground" with Q1 (pnp transistor) to the inputs, the printer port acts this way.
I took the ground for the inputs and put it to the p-plugs ground, and it has done ok or the last two reboots.
I think Windows is doing some screwy things with my port, and everyone may not have the same experiences I am having.
But for now, the attached drawing shows what seems to be working.
But since I still have not received my optos, I will leave the test rig connected and watch the leds each time I boot up.
Side note: Koz319 is working on a neat program for this, but I think it is for windows only (But I may be wrong). Anyway, I wrote some logic once for my job that used the printer port for real world I/O. This project used a dos computer. I wrote the program in QBasic, which will run in DOS. If there is enough interest from DOS users, I can try to copy what Koz319 is doing for DOS.
DaOld Man:
--- Quote from: bfauska on November 15, 2007, 11:30:28 am ---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.
--- End quote ---
I think I posted the last post while you were posting...
That sounds like a neat idea, but you would have to degauss at end of rotation, unless you use a lcd monitor.
DaOld Man:
Ok, I have found that I cannot connect the pnp transistors base to pin 4.
Pin 4 is set high by windows on startup, why, Im not sure, may be windows is trying to que the printer through that output?
Anyway, I will be connecting the transistor to pin 7. It seems to go back low after windows loads.
Aint Windows just grand?
DaOld Man:
I have still not received my opto isolators from ebay. I am beginning to think I may have gotten ripped.
My Radio Shack doesnt have any, so I may have to order elsewhere.
I hooked my test bread board and my H drive, power supply. and motor to a old windows 98 machine I have.
It seems to work just fine, but I would still feel better using the optos on my mame PC.
Anyway, I wrote a small DOS program that allows me to plug in "on" and "off" times to toggle the #2 printer pin on and off.
I was experimenting with motor speed control. (Pulse Width Modulation, or PWM)
I came to these conclusions:
With H drive forward input connected to Printer Port Pin #2.
I can control the speed of the motor by varying the on and off times.
But it does have its drawbacks.
First of all, the motor is being turned off and on, so it constantly jerks.
The motor is more noisy.
The H Drives power transistors got pretty hot, so I think heat sinks will be a must if you plan to use PWM.
I cannot measure the motors speed, because I dont have a tachometer, but I can clearly see a difference in speed.
I tried 1 millisecond (ms) on and 300 ms off. This seems to get a pretty slow speed.
Seems like increasing the time on makes less difference than increasing the time off.
I am planning to build a program to rotate the monitor in DOS.
I probably wont use it, since my mame machine is on a windows XP machine.
But it is letting me develop PWM, and it will be cool for those who still use DOS.
If anyone's interested please let me know.
Using your printer port for I/O is a lot easier in DOS than it is in Windows.
You dont need an external driver in DOS.
theCoder:
--- Quote from: DaOld Man on November 20, 2007, 01:16:39 am ---I cannot measure the motors speed, because I don't have a tachometer, but I can clearly see a difference in speed.
I tried 1 millisecond (ms) on and 300 ms off. This seems to get a pretty slow speed.
Seems like increasing the time on makes less difference than increasing the time off.
--- End quote ---
1 ms seems awfully short a duration to try to drive a motor. Especially a 1/300 duty cycle. Are you sure you are actually getting one ms on. The "less difference" may (??) be that the line is not outputting what you are expecting. If you have access to one, you might put an oscilloscope on your drive line.
Glad to hear you have motion anyway. Keep it up.
Too bad on the chips. I usually buy my stuff from Newark.com. Ebay is hit or miss on components.
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