DC motor speed control signal
I need a tachometer signal to time slow rotations (10-80 deg/sec) of a
4-inch drum driven by a DC motor. Is it realistic to try to print an
alternating black/white stripe sequence on a laser printer, tape it around
the drum, and then to "watch" this sequence with a source/receiver
photodiode to generate a square wave tachometer signal? If so, would
printing on white paper be OK, or is another surface better?
Thanks,
Dennis
4-inch drum driven by a DC motor. Is it realistic to try to print an
alternating black/white stripe sequence on a laser printer, tape it around
the drum, and then to "watch" this sequence with a source/receiver
photodiode to generate a square wave tachometer signal? If so, would
printing on white paper be OK, or is another surface better?
Thanks,
Dennis
Comments
reflective photosensors at about 3/4 inch and had good results. The ones
I've used have the emitter and sensor mounted at "an optimal angle" in a
plastic body with a mounting slot. I think Digikey has these for a buck
or two each.
On Sun, 25 Feb 2001 20:49:46 -0800 "Dennis P. O'Leary"
<doleary@h...> writes:
> I need a tachometer signal to time slow rotations (10-80 deg/sec) of
> a
> 4-inch drum driven by a DC motor. Is it realistic to try to print an
> alternating black/white stripe sequence on a laser printer, tape it
> around
> the drum, and then to "watch" this sequence with a source/receiver
> photodiode to generate a square wave tachometer signal? If so,
> would
> printing on white paper be OK, or is another surface better?
>
> Thanks,
> Dennis
>
>
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
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>4-inch drum driven by a DC motor. Is it realistic to try to print an
>alternating black/white stripe sequence on a laser printer, tape it around
>the drum, and then to "watch" this sequence with a source/receiver
>photodiode to generate a square wave tachometer signal? If so, would
>printing on white paper be OK, or is another surface better?
>
>Thanks,
>Dennis
Hi Dennis,
A laminated plastic film _might_ be better from the standpoint of
dimensional stability and water/oil resistance. For inkjet
printing, I swear by the white opaque polyester film from Luminos:
http://www.lumijet.com/Lumijet.htm
best regards,
-- Tracy
couple magnets glued to the inside or outside of the drum. You'll
want to get a PAK-VII from http://www.al-williams.com/awce/ so you
can count the two channels at once. You could count rotations with a
single sensor, but for RPM's, two would be best mounted 90 degrees
apart and measure the time between them.
Hope this helps...
- Brice
> >I need a tachometer signal to time slow rotations (10-80 deg/sec)
of a
> >4-inch drum driven by a DC motor. Is it realistic to try to print
an
> >alternating black/white stripe sequence on a laser printer, tape
it around
> >the drum, and then to "watch" this sequence with a source/receiver
> >photodiode to generate a square wave tachometer signal? If so,
would
> >printing on white paper be OK, or is another surface better?
> >
> >Thanks,
> >Dennis
>
>
> Hi Dennis,
> A laminated plastic film _might_ be better from the standpoint of
> dimensional stability and water/oil resistance. For inkjet
> printing, I swear by the white opaque polyester film from Luminos:
> http://www.lumijet.com/Lumijet.htm
>
>
> best regards,
> -- Tracy
>
>
>
>
> Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
>
>
problem requires such slow rotations, less than 1/4 revolution per second,
I'm trying a really simple approach -- operating "open loop" without a tach
signal. I'm using a 12 V geared, DC reversible motor from Jameco which
requires only 45 mA at no load. I need 4 constant velocities, selectable by
4 pins on a Stamp, so the plan is to use 4 open-collector channels of a
ULN2003 driver chip, each with a different valued 1% current-limiting
resistor in series with the motor's ground. The resistor values will
determine the speed to an accuracy of about 1%, and a regulated 12 V supply
will keep everything more or less stable, at least in theory. This does
require 4 stamp pins, each selecting a motor speed, but simplifies
programming and parts count.
I though this approach might also be useful for some slow 'Bot applications,
like arm or head movements.
Dennis
Original Message
From: Orrin f Drew [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=ZH8fjfwf1s1lr4FaBcDfwypT4CwOnbJ3oxJWA612IagqDEVnujLh-ZczjLxAx6aUlZqu8HYZ6A]odrew@j...[/url
Sent: Sunday, February 25, 2001 9:27 PM
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] DC motor speed control signal
Good method, works pretty good especially for slow signals. I've used IR
reflective photosensors at about 3/4 inch and had good results. The ones
I've used have the emitter and sensor mounted at "an optimal angle" in a
plastic body with a mounting slot. I think Digikey has these for a buck
or two each.
On Sun, 25 Feb 2001 20:49:46 -0800 "Dennis P. O'Leary"
<doleary@h...> writes:
> I need a tachometer signal to time slow rotations (10-80 deg/sec) of
> a
> 4-inch drum driven by a DC motor. Is it realistic to try to print an
> alternating black/white stripe sequence on a laser printer, tape it
> around
> the drum, and then to "watch" this sequence with a source/receiver
> photodiode to generate a square wave tachometer signal? If so,
> would
> printing on white paper be OK, or is another surface better?
>
> Thanks,
> Dennis
>
>
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
________________________________________________________________
GET INTERNET ACCESS FROM JUNO!
Juno offers FREE or PREMIUM Internet access for less!
Join Juno today! For your FREE software, visit:
http://dl.www.juno.com/get/tagj.
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
speeds.
Original Message
> Thanks to Tracy, Orrin and Brice for good suggestions. Because my drum
> problem requires such slow rotations, less than 1/4 revolution per second,
> I'm trying a really simple approach -- operating "open loop" without a
tach
> signal. I'm using a 12 V geared, DC reversible motor from Jameco which
> requires only 45 mA at no load. I need 4 constant velocities, selectable
by
> 4 pins on a Stamp, so the plan is to use 4 open-collector channels of a
> ULN2003 driver chip, each with a different valued 1% current-limiting
> resistor in series with the motor's ground. The resistor values will
> determine the speed to an accuracy of about 1%, and a regulated 12 V
supply
> will keep everything more or less stable, at least in theory. This does
> require 4 stamp pins, each selecting a motor speed, but simplifies
> programming and parts count.
>
> I though this approach might also be useful for some slow 'Bot
applications,
> like arm or head movements.
>
> Dennis
>
>
Original Message
> From: Orrin f Drew [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=qIp3hyRoUgPFJf5BL94W8KVUJ1LeGc_VBndSmybdeXVHtrO4VN0ZjOnIj4_EFqi49q_2qQ]odrew@j...[/url
> Sent: Sunday, February 25, 2001 9:27 PM
> To: basicstamps@yahoogroups.com
> Subject: Re: [noparse][[/noparse]basicstamps] DC motor speed control signal
>
>
> Good method, works pretty good especially for slow signals. I've used IR
> reflective photosensors at about 3/4 inch and had good results. The ones
> I've used have the emitter and sensor mounted at "an optimal angle" in a
> plastic body with a mounting slot. I think Digikey has these for a buck
> or two each.
>
> On Sun, 25 Feb 2001 20:49:46 -0800 "Dennis P. O'Leary"
> <doleary@h...> writes:
> > I need a tachometer signal to time slow rotations (10-80 deg/sec) of
> > a
> > 4-inch drum driven by a DC motor. Is it realistic to try to print an
> > alternating black/white stripe sequence on a laser printer, tape it
> > around
> > the drum, and then to "watch" this sequence with a source/receiver
> > photodiode to generate a square wave tachometer signal? If so,
> > would
> > printing on white paper be OK, or is another surface better?
> >
> > Thanks,
> > Dennis
> >
> >
> >
> >
> > Your use of Yahoo! Groups is subject to
> > http://docs.yahoo.com/info/terms/
> >
> >
>
> ________________________________________________________________
> GET INTERNET ACCESS FROM JUNO!
> Juno offers FREE or PREMIUM Internet access for less!
> Join Juno today! For your FREE software, visit:
> http://dl.www.juno.com/get/tagj.
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>