Mechanical TV Project

Forum for discussion of narrow-bandwidth mechanical television

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Re: Mechanical TV Project

Postby FlyMario » Wed Mar 27, 2019 11:57 pm

These days I keep thinking I might need to get a Faster motor and gear it down or perhaps gear this motor down. Feel like me running the motor under voltage is not making it as reliable as it should be. Slight power increases feel also like it makes too much of a change. Maybe I do need a little more torque.

Peter.
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Re: Mechanical TV Project

Postby smeezekitty » Thu Mar 28, 2019 3:50 am

It does sound like you would benefit from more torque (not more speed)
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Re: Mechanical TV Project

Postby FlyMario » Thu Mar 28, 2019 8:34 am

smeezekitty wrote:It does sound like you would benefit from more torque (not more speed)


I have a new 2000 rpm motor. Ordered a 20 tooth and 50 tooth pully which should be in tomorrow. If I do my math right, that setup should give me 800rpm. Hopefully, I don't lose much torque by slowing the motor down to a resulting 750rpm. :roll: The original motor is 1000rpm directly driving the disk down to 750rpm. That is quite a difference.

Peter
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Re: Mechanical TV Project

Postby Harry Dalek » Thu Mar 28, 2019 6:34 pm

Doing 60 line ,a pulley system is a good idea for the higher line rates ..good luck
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Re: Mechanical TV Project

Postby Andrew Davie » Thu Mar 28, 2019 7:45 pm

FlyMario wrote:
smeezekitty wrote:It does sound like you would benefit from more torque (not more speed)


I have a new 2000 rpm motor. Ordered a 20 tooth and 50 tooth pully which should be in tomorrow. If I do my math right, that setup should give me 800rpm. Hopefully, I don't lose much torque by slowing the motor down to a resulting 750rpm. :roll: The original motor is 1000rpm directly driving the disk down to 750rpm. That is quite a difference.

Peter


My experience/experiments with toothed belts (if I understand the use of your 20/50 tooth pulleys) is that they are *incredibly noisy* at the speeds for NBTV.
I pretty quickly abandoned toothed belts for smooth pulleys and an oversized O-ring as used for underwater sealing in submersibles. This worked extremely well.
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Re: Mechanical TV Project

Postby FlyMario » Thu Mar 28, 2019 7:56 pm

Nah. Just working to get 750 rpm to be more stable.
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Re: Mechanical TV Project

Postby FlyMario » Fri Mar 29, 2019 1:48 am

Robonz wrote:If you want really consistent results, shining this through a hole is pretty unbeatable. Reflective sensors suffer from poor contrast versus through beam. I use this circuit for rock solid sync. I normally use a 4k7 resistor for the phototransistor. You do want a good led and photo transistor for best good results.

Your photo transistor should look "black" e.g. ir pass filter


Yeah I am going to take this advice. I printed these two encoder wheels...

20190328_104052.jpg


I am not entirely sure which I will use. Seems kind of redundant maybe to use the wheel with all the teeth because we could generate the pulses.

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Re: Mechanical TV Project

Postby FlyMario » Sat Mar 30, 2019 1:56 am

Andrew Davie wrote:
FlyMario wrote:
smeezekitty wrote:It does sound like you would benefit from more torque (not more speed)


I have a new 2000 rpm motor. Ordered a 20 tooth and 50 tooth pully which should be in tomorrow. If I do my math right, that setup should give me 800rpm. Hopefully, I don't lose much torque by slowing the motor down to a resulting 750rpm. :roll: The original motor is 1000rpm directly driving the disk down to 750rpm. That is quite a difference.

Peter


My experience/experiments with toothed belts (if I understand the use of your 20/50 tooth pulleys) is that they are *incredibly noisy* at the speeds for NBTV.
I pretty quickly abandoned toothed belts for smooth pulleys and an oversized O-ring as used for underwater sealing in submersibles. This worked extremely well.


Fascinating. I expected the exact same thing. But oddly enough my setup is actually nearly silent. Hopefully, I can post a video of it later.

Check out this hack of a test.

NewMotor.jpg


And the Drive...

NewMM.jpg


A little frustrated because I am having to run the motor at over 12v (13.2) to get it near 750 rpm. I wanted the hole machine to run at 12vdc. Hoping that my RPM indicator in Arduino just doesn't have a good resolution. 1 pulse per second can make it appear 660rpm or 720rpm LOL.

May need to change the gear ratio later. Worrying too much about something I don't even have accurate info yet

Pete
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Re: Mechanical TV Project

Postby smeezekitty » Sat Mar 30, 2019 4:02 am

A much more accurate way to measure the RPM is to measure how many milliseconds or microseconds it takes to go from rising edge to rising edge or falling edge to falling edge.
Measuring to within 1mS would give you 10RPM precision.
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Re: Mechanical TV Project

Postby FlyMario » Sat Mar 30, 2019 6:56 am

smeezekitty wrote:A much more accurate way to measure the RPM is to measure how many milliseconds or microseconds it takes to go from rising edge to rising edge or falling edge to falling edge.
Measuring to within 1mS would give you 10RPM precision.


Cool. Yeah, I measured Micros() and I am definitely running slow. I had to go to 13.2v and confirmed the results is right around 80k.

Printed the encoder sensor mount. (no more cardboard)
MTV1.jpg


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Re: Mechanical TV Project

Postby FlyMario » Sat Mar 30, 2019 7:07 am

I posted a video on the new drive.

https://youtu.be/ls9NFnHk77g

You know... Mechanical Devices are very frustrating. It can't just stay at one speed.

I wonder if Andrews belt had teeth taller than the depth of the timing pully. The belts are GT2 (2GT whatever).

Peter
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Re: Mechanical TV Project

Postby Harry Dalek » Sat Mar 30, 2019 8:47 am

FlyMario wrote:I posted a video on the new drive.

https://youtu.be/ls9NFnHk77g

You know... Mechanical Devices are very frustrating. It can't just stay at one speed.

I wonder if Andrews belt had teeth taller than the depth of the timing pully. The belts are GT2 (2GT whatever).

Peter


i used the idea more than once ....look what i did here on the polygon mirror i made the belt adjustable i found the tension of the belt is very important once correct the electronics driving the motor will work fine.
viewtopic.php?f=1&t=1795&hilit=mirror+camera
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