Mechanical TV Project

Forum for discussion of narrow-bandwidth mechanical television

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Re: Mechanical TV Project

Postby Robonz » Wed Aug 01, 2018 1:08 pm

Can you post up your sync separator schematic? I might be able to spot the noise issue. And a photo of your construction would be good.

You can see my diffuser here
http://www.taswegian.com/NBTV/forum/viewtopic.php?f=35&t=2447&start=15#p22524

If you ask at a signage company they will give you a scrap of 4.5mm thick "opal" acrylic for free I would bet. Its pretty hard to beat. And yes, you definitely need it to hide the light source from showing in your image.

Cheers
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Re: Mechanical TV Project

Postby FlyMario » Wed Aug 01, 2018 11:13 pm

I hate analog circuits! I can't believe I picked a project that would need me to deal with analog.

I think I need to reverse my video signal + / - on the OP-AMP. I think anything getting near 0 volts is triggering the comparator. I have to turn my pot all the way to the right to get the signal to trigger. In reality, I shouldn't even need a pot if the signal was inverted. Just like a 1k or so resistor should be enough to say the inverted voltage went above 0 volts. When I first put the circuit together I thought it would need to be inverted but since it was working I went with it.
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Re: Mechanical TV Project

Postby FlyMario » Fri Aug 03, 2018 2:59 pm

Tonight I put together my lightbox and wired up my white LEDs in 2 sets of three in series. Using a 24ohm resistor on each set. I applied 12v slowly. I was afraid my bench power supply was going to destroy the LEDs but, they survived. They claim to be 13000mcd and they are very bright. After going down the 75mm box through the 3 pieces of Parchment baking paper I am satisfied with the diffusion. However, I am not so convinced the output will be bright enough.
Attachments
LightBoxFwd.jpg
LightBoxMounted.jpg
Diffused.jpg
Bright.jpg
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Re: Mechanical TV Project

Postby FlyMario » Fri Aug 03, 2018 3:08 pm

Also, I really don't think I like stripboard anymore. I am loosing too many OP Amps because I get in a hurry and don't drill the traces. Lost an arduino on this project as well for that crap.
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Re: Mechanical TV Project

Postby smeezekitty » Fri Aug 03, 2018 4:04 pm

I like the idea of modeling the light box with holes for the LEDs. Much more elegant than my method of soldering them on a pref board and taping it to the lightbox

Hard to tell based on the camera exposure but I bet it will be bright enough. The diffusion is okay but you will likely see the diffuser texture through the picture
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Re: Mechanical TV Project

Postby Harry Dalek » Fri Aug 03, 2018 6:13 pm

i always used 2 or 3 layers of milk bottle plastic that worked for me used it in fact on the 2 drum monitor builds..the type of plastic used will defocus the leds.
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Re: Mechanical TV Project

Postby FlyMario » Tue Aug 07, 2018 12:54 am

smeezekitty wrote:Hard to tell based on the camera exposure but I bet it will be bright enough. The diffusion is okay but you will likely see the diffuser texture through the picture


Yes, I agree. Damn... I guess I better just get some plastic as Harry suggests. That diffuser texture will surely be part of the video. :(
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Re: Mechanical TV Project

Postby Harry Dalek » Tue Aug 07, 2018 11:04 pm

FlyMario wrote:
smeezekitty wrote:Hard to tell based on the camera exposure but I bet it will be bright enough. The diffusion is okay but you will likely see the diffuser texture through the picture

Yes, I agree. Damn... I guess I better just get some plastic as Harry suggests. That diffuser texture will surely be part of the video. :(


Here is where i used the idea well at least showed what i was up to on one of the 2 drum designs with the mechanical sawtooth slit drum

viewtopic.php?f=1&t=1486&hilit=drum+monitor&start=60
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Mechanical TV Project

Postby FlyMario » Tue Aug 07, 2018 11:33 pm

Harry Dalek wrote:Here is where i used the idea well at least showed what i was up to on one of the 2 drum designs with the mechanical sawtooth slit drum

viewtopic.php?f=1&t=1486&hilit=drum+monitor&start=60


That a milk jug that you used as the diffuser? Recycling!
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Re: Mechanical TV Project

Postby Harry Dalek » Wed Aug 08, 2018 2:16 pm

FlyMario wrote:
That a milk jug that you used as the diffuser? Recycling!


Yes pretty much those squareish ones trying to cut out the 4 flat panels for fitting in the drum.. don't think i bothered with the side with the sticker to get that off up higher :wink:
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Re: Mechanical TV Project

Postby FlyMario » Sat Aug 18, 2018 3:45 pm

So I made a video of my Mechanical TV running. It is trying to show a picture but It has quite a bit more work to be done.

The video output is not nearly as advanced as the club circuit. Very certain that my brightness is nowhere near what it can be.

The only sync going on is trying to maintain 12.5fps... very poorly. Definitely, need a nice PID code. My motor seems to change speed more than I would like.

I am so very very frustrated how sensitive the damned ir sensor is. I even have printed it in black. My lord.

And yeah... I am sending way more sync pulses from the video signal. Need to sort that crap out.

But, I am very happy that I have at least a good point to work from.

https://youtu.be/VyGzavKxlzg
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Re: Mechanical TV Project

Postby smeezekitty » Sat Aug 18, 2018 5:32 pm

I find the levels on the MUTR files a little on the low side. You might get better results if you load it into a program like Audacity and run amplify.
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Re: Mechanical TV Project

Postby FlyMario » Sun Aug 19, 2018 9:39 am

So I posted a second video of the Mechanical TV functioning.

https://youtu.be/PinWKUnAgXM

Speed Readings.jpg
Speed Readings.jpg (35.36 KiB) Viewed 5610 times

Here is the readings from the Arduino. The first column is the speed of the PWM out for the motor, second column RPM frame time and the third is the Frame time from the Sync Pulses. I am very happy as I have cleaned up the Sync pulses from the video in.

IR Module.jpg

I had replaced my RPM indicator with one of these modules. Oh these are such crap. No matter what I did I could not get a solid signal.

So I went back to using my OP Amp circuit (common from the google machine) and am so very pleased. Solid.
RPM Indicator.jpg


IR Circuit.jpg
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Re: Mechanical TV Project

Postby Steve Anderson » Tue Aug 21, 2018 8:00 pm

Your problem with the Chinese-made module maybe one or both of two things. First, depending on the distance from the disc to the LED and detector, they may need angling in towards each other for better coverage and sensitivity - looking at the photo that may be difficult to achieve. A lot of these devices have a beam-width/sensitivity curve of only some +/-10 degrees.

Second is if the disc markings for this are printed (laser or ink-jet) rather than 'done in hardware' a lot of inks (black in this case I assume) are reflective at IR.

I hope this helps...

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Re: Mechanical TV Project

Postby FlyMario » Tue Aug 21, 2018 9:06 pm

Steve Anderson wrote:Your problem with the Chinese-made module maybe one or both of two things. First, depending on the distance from the disc to the LED and detector, they may need angling in towards each other for better coverage and sensitivity - looking at the photo that may be difficult to achieve. A lot of these devices have a beam-width/sensitivity curve of only some +/-10 degrees.

Second is if the disc markings for this are printed (laser or ink-jet) rather than 'done in hardware' a lot of inks (black in this case I assume) are reflective at IR.

I hope this helps...

Steve A.


Yeah, honestly I went down that route because for some reason I could not figure out why a simple OP-AMP and IR Receiver Diode would not work as it had for me before. You see, I had put the output into an Arduino chip. I had failed to program the chip to have that pin be an input... in fact, I had not programmed it at all and just relied on a led to indicate the mark had passed. The Arduino chip was messing with my results. So I decided to use that module.

When I tried the little module it seemed to show promise and I began programming the Arduino chip and monitoring the time between the mark passing. After determining the module could not really give me the results I was looking for, I plugged back in my IR Led's and my original mistake slapped me in the face. That original circuit worked! LOL. It was the Atmega328 chip and my rush to put it in the circuit without even programming it causing me a weeks worth of grief. It works perfectly now.

I have way too many hobbies and have much more determination than skill. :)

Thanks for your comment, Steve. The module was so sensitive to any light. I even had it set so close to the disk at one time it would hit here and there. It would still get pulses on an extremely low setting. It was designed for line following robots. Its sensitivity would make it totally useless for that thus making a bunch of kids very sad.
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