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Weird

Posted by L4ZX55 
Weird
April 29, 2012 11:53AM
Hi everyone, I was just messing with the torque on my X axis while the power was on (I know it's a major no-no but I'm impatient), and the strangest thing happened, I started to receive a radio signal. I was using an all metal screwdriver to adjust the trimpot and suddenly my motor started making a strange noise, turns out it was playing some talk show (rather clearly). I figure I must have caused the screwdriver to become a antenna allowing the driver to translate the incoming signal into magnetic signals which caused the motor to become some sort of rudimentary speaker. I swear I'm not making this up. Beyond this strangeness I'm really interested in knowing if this is harmful, beneficial, unique, etc...
I have a sanguinololu 1.3a, and one of reprapme.com's stepper drivers.

P.S. Is this the part of the forum i should even be posting this on?
Re: Weird
April 29, 2012 12:00PM
I have no real understanding of what is going on and absolutely no idea what effects it may have on the electronics, but I just wanted to say that is very interesting. I have used the stepper motors to play midi music based on varying federates and distances. However, I have never heard voices reproduced by stepper motors and think it would be cool to see.
Re: Weird
April 29, 2012 12:21PM
L4ZX55 Wrote:
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> beneficial

This would depend on if you wanted to listen to said talk show.

I'd doubt it would be harmful to the motors. (Unless it's a really boring talk show, where you may bore the motors to death.)
Re: Weird
April 29, 2012 01:21PM
I have noticed a change in the sound of the motor when adjusting the trimpot with a screwdriver.

I've never picked up a radio signal though! That's very interesting!

All I get is a louder hiss.
Re: Weird
April 29, 2012 02:43PM
Well it's settled. Your printer is haunted. I can only advise you to print a cross immediately and perform an exorcism.

Good luck...

bdc
~Stay Calm Out There
Re: Weird
April 29, 2012 03:14PM
Is it realy a bad idea to adjust pots while the machine is on? I do that regularly while setting up my printers. What's the worst that could happen if doing this?
Re: Weird
April 29, 2012 03:19PM
miro87043 Wrote:
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> Is it realy a bad idea to adjust pots while the
> machine is on? I do that regularly while setting
> up my printers. What's the worst that could happen
> if doing this?

It jumps as you turn it and you end up driving it with way too much current, or you slip and short something out.
Re: Weird
April 29, 2012 04:18PM
yngndrw Wrote:
-------------------------------------------------------
> miro87043 Wrote:
> --------------------------------------------------
> -----
> > Is it realy a bad idea to adjust pots while the
> > machine is on? I do that regularly while
> setting
> > up my printers. What's the worst that could
> happen
> > if doing this?
>
> It jumps as you turn it and you end up driving it
> with way too much current, or you slip and short
> something out.

Okay. I had considered the slip and short, but I did not realize the current would spike. It's my guess that a short spike isn't likely to warm up the winding enough to cause damage, but it's probably not worth the risk.

I'm curious if anybody has actually damaged there stepppers by adjusting there pots while powered up.
Re: Weird
April 29, 2012 04:27PM
The reason for it is that a potentiometer is just a carbon track with a metal wiper which moves across it and as it turns it may jump. Some Pololus have caught fire (For other reasons) which suggests that they are rather sensitive.

You wouldn't damage the stepper this way.

The way I adjust mine is by measuring the voltage (With just 5V applied, the motor's power supply is off), switch it off, turn the potentiometer and switch it back on / measure again. I found that with the Pot set to about half it was at 2A and about a quarter it was at 1A as a guide.
Re: Weird
April 29, 2012 05:18PM
I've been curious about how to properly set a pot. I just use trial and error. I'll have to try that.

Thanks!
Re: Weird
July 16, 2012 04:41PM
I got same thing happening today, and I took it as a sign to change the pololu driver.
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