color wheel monitor - Videokarma.org TV - Video

mbates14 · #1 08-09-2007, 10:01 PM

I got bored one day, and decided to work with chris benham on a color wheel monitor project. i got the circuit completed and working.

the hardest part of the whole project was the motor control servo. but i decided to write a program for a CPU, and i have full control.

What do you think?

http://img525.imageshack.us/my.php?i...sc00402el0.jpg

http://img175.imageshack.us/my.php?i...sc00403nu4.jpg

http://img158.imageshack.us/my.php?i...sc00404mn3.jpg

old_tv_nut · #2 08-09-2007, 10:28 PM

Nice! What is the scanning rate? Presume it's running from the computer VGA output? How big is it?

Pete Deksnis · #3 08-10-2007, 09:14 AM

Really nice job. It's interesting to see an Elenco put to such 'practical' use!

similost · #4 08-10-2007, 09:33 AM

I think that's pretty damn cool!!! I just wouldn't try traveling through any airports with that case...

mbates14 · #5 08-10-2007, 09:44 AM

its 640x480 at 60hz. the flicker is horrible, but my monitor wont go past 60hz becuase the horizontal rate it cant handle.

mbates14 · #6 08-10-2007, 09:48 AM

also the most interesting thing about this project is i have the motor control servo running in a processor, with custom control code. all PWM.

the first MOSFET controls the motor current, (which is un-needed, so i disconnected it). and the second mosfet is the PWM controller output.

basically it has a wide lock range. dont have to adjust gain, or anything. just power it on and it locks.

i can change the refresh rate to 80hz, and itll lock it without touching anytrhing. except you cant read whats on the display, becuase it cant support it.

old_tv_nut · #7 08-10-2007, 10:32 PM

I used PWM for my mechanical TV with similar results - no adjustments needed, just pulls in to whatever the incoming video is. However, supplying pulsed current to the DC motor does make it buzz/hum. How's yours noise-wise?

mbates14 · #8 08-10-2007, 11:59 PM

cant hear anything. i have it set about 50khz.

Richard D · #9 08-11-2007, 07:41 PM

Real nice work Mike. With school and all how did you find the time?
Richard.

mbates14 · #10 08-11-2007, 07:44 PM

im out of school now. been out since december.

old_tv_nut · #11 08-13-2007, 09:58 PM

Quote:

Originally Posted by mbates14

cant hear anything. i have it set about 50khz.

AHA. My mechanical set runs at 400 Hz, convenient becuase it's the line scan rate. - makes the motor whine.

mbates14 · #12 08-13-2007, 10:36 PM

ah you made a PWM controller for a nipkow? or something like that.

i thought about that, but i never did do that becuase i wasnt as fluent in processors.

processors makes it really nice. all you need is a mosfet, an opto-coupler to upstep 5V to about 9v to fully-on the mosfet, a chip and thats it. no resistors, capacitors, or nothing. single chip motor control .

Richard D · #13 08-11-2007, 07:54 PM

WOW, Time does fly when you get old. Shoot me a PM or email so I can catch up.
Richard.

old_tv_nut · #14 08-14-2007, 10:12 PM

Yes a PWM for the scanning disk - however, done with 555 timers instead of a microcontroller.

mbates14 · #15 08-14-2007, 10:21 PM

555 timers and a phase comparator? use the voltage output to control the duty cycle?