Voltage spikes and big loads...
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Posts: 46,084
Adrian,
One thing to remember with MOV's - You never know when
they've been blown until it's too late... They're
great for protecting circuits, but they only take so
may spikes before they blow out. And once they have
(in most of the MOV protected computer surge
protectors), you don't know.
Anyone know how to test one (short of hi-pot'ing it
<which could cause it to then burn out>)???
THE REAL QUESTION:
My real question was, what the experience is driving
relatively LARGE motor loads with a BS2.
I'm in the process of putting together a fair sized
robot platform, and expect to use some fairly hefty
motors to drive it - though still on the order of 6-12
volts.
I've played a little with driving a simple gearmotor,
and ordered H-bridge drivers for it. Before the BS2
had arrived, I hooked up a 555 timer circuit to try
driving the PWM function and see if I could control
the speed of the motor.
Under load, the noise from the motor was enough to
completely disrupt the 555 circuit.
Now, I'm aware of the standard practices of putting
the 3 cap's on the motors, and reverse bias diodes on
the driving transistors. But I'm suspicious that this
will only take care of so much.
I have no problem using separate voltage regulators
for the drive electronics vs. the logic/controller
circuitry. And I'm getting ready to order
opto-isolators if I need them.
How much will the capacitors take care of, and at what
point do you have to go to totally isolated circuits
with separate power supplies?
Thanks!
J.
--- Adrian <adrian650@y...> wrote:
> As there have been few replies,
>
> I looked into the issue of frying-stamps as I'm
> using
> one in an autootive environment where higher voltage
> transitions may occur if regulator fails, HT noise
> etc
> etc. It appeared to me that MOVs were a possible
> solution. At a given voltage they become open
> circuit
> and will pass a substantial current for a short
> time.
>
> From the data sheet you need to choose one that is
> closed at the normal voltage but opens at a voltage
> above normal but below the STAMP regulator failure
> voltage - using an external linear regulator might
> give more latitude here.I understand that a MOV
> alone
> will suppress a tranisent and suspect that they will
> survive long enough to blow a quick-blow fuse in
> series with PSU.
>
> Adrian
>
>
> =====
> -
> *********************************************
>
>
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One thing to remember with MOV's - You never know when
they've been blown until it's too late... They're
great for protecting circuits, but they only take so
may spikes before they blow out. And once they have
(in most of the MOV protected computer surge
protectors), you don't know.
Anyone know how to test one (short of hi-pot'ing it
<which could cause it to then burn out>)???
THE REAL QUESTION:
My real question was, what the experience is driving
relatively LARGE motor loads with a BS2.
I'm in the process of putting together a fair sized
robot platform, and expect to use some fairly hefty
motors to drive it - though still on the order of 6-12
volts.
I've played a little with driving a simple gearmotor,
and ordered H-bridge drivers for it. Before the BS2
had arrived, I hooked up a 555 timer circuit to try
driving the PWM function and see if I could control
the speed of the motor.
Under load, the noise from the motor was enough to
completely disrupt the 555 circuit.
Now, I'm aware of the standard practices of putting
the 3 cap's on the motors, and reverse bias diodes on
the driving transistors. But I'm suspicious that this
will only take care of so much.
I have no problem using separate voltage regulators
for the drive electronics vs. the logic/controller
circuitry. And I'm getting ready to order
opto-isolators if I need them.
How much will the capacitors take care of, and at what
point do you have to go to totally isolated circuits
with separate power supplies?
Thanks!
J.
--- Adrian <adrian650@y...> wrote:
> As there have been few replies,
>
> I looked into the issue of frying-stamps as I'm
> using
> one in an autootive environment where higher voltage
> transitions may occur if regulator fails, HT noise
> etc
> etc. It appeared to me that MOVs were a possible
> solution. At a given voltage they become open
> circuit
> and will pass a substantial current for a short
> time.
>
> From the data sheet you need to choose one that is
> closed at the normal voltage but opens at a voltage
> above normal but below the STAMP regulator failure
> voltage - using an external linear regulator might
> give more latitude here.I understand that a MOV
> alone
> will suppress a tranisent and suspect that they will
> survive long enough to blow a quick-blow fuse in
> series with PSU.
>
> Adrian
>
>
> =====
> -
> *********************************************
>
>
________________________________________________________________________
> Yahoo! Messenger - Communicate instantly..."Ping"
> your friends today! Download Messenger Now
> http://uk.messenger.yahoo.com/download/index.html
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed.
> Text in the Subject and Body of the message will be
> ignored.
>
>
> Yahoo! Groups Links
>
> To visit your group on the web, go to:
> http://groups.yahoo.com/group/basicstamps/
>
> To unsubscribe from this group, send an email to:
> basicstamps-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject to:
> http://docs.yahoo.com/info/terms/
>
>
__________________________________
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Comments
>Adrian,
>
>One thing to remember with MOV's - You never know when
>they've been blown until it's too late... They're
>great for protecting circuits, but they only take so
>may spikes before they blow out. And once they have
>(in most of the MOV protected computer surge
>protectors), you don't know.
>
>Anyone know how to test one (short of hi-pot'ing it
><which could cause it to then burn out>)???
>
>THE REAL QUESTION:
>
>My real question was, what the experience is driving
>relatively LARGE motor loads with a BS2.
>
>I'm in the process of putting together a fair sized
>robot platform, and expect to use some fairly hefty
>motors to drive it - though still on the order of 6-12
>volts.
>
>I've played a little with driving a simple gearmotor,
>and ordered H-bridge drivers for it. Before the BS2
>had arrived, I hooked up a 555 timer circuit to try
>driving the PWM function and see if I could control
>the speed of the motor.
>
>Under load, the noise from the motor was enough to
>completely disrupt the 555 circuit.
>
>Now, I'm aware of the standard practices of putting
>the 3 cap's on the motors, and reverse bias diodes on
>the driving transistors. But I'm suspicious that this
>will only take care of so much.
>
>I have no problem using separate voltage regulators
>for the drive electronics vs. the logic/controller
>circuitry. And I'm getting ready to order
>opto-isolators if I need them.
>
>How much will the capacitors take care of, and at what
>point do you have to go to totally isolated circuits
>with separate power supplies?
>
>Thanks!
>J.
J. -
You may want to look into using a separate motor controller board, such as the
one offered here:
http://divelec.tripod.com/id1.html
I have had very good luck with these motor controllers, and can vouch for
their durability. Take a look at the control circuity there as well.
You may also want to re-consider the use of 6 or 12 volt motors in favor of
using
motors of a higher voltage. The single biggest advantage is the lower amperage
draw. This permits you to down size many of the components used. The higher the
voltage, the lower the amperage for a given horsepower motor. This is even true
in the fractional horsepower range.
Many of the motorized platforms which use "hefty" DC motors today, start at
24-48 VDC, and go up to 96-130 VDC. Simple one wire or two wire control from the
Stamp is all that is really needed. This permits the Stamp to do many of the
more important function, and leaves the driving of the motor to an off-board
facility.
Additionally, when using an off-board motor controller there is little need to
worry about any signal or noise interaction between the Stamp and the control
circuitry. If you were to use shielded control cables between the Stamp and the
motor control board, I'd hazard to say there would be no chance of any harmful
interference.
Lastly, since all of the high amperage and higher voltage requirements take
place away from the Stamp, there is far less chance of potential damage to the
Stamp.
This is obviously one of your present concerns.
I hope you find these suggestions helpful.
Regards,
Bruce Bates
check out http://www.geocities.com/jimforkin2003/
jim
Original Message
From: oak [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=oPoulNoLzSxSWiBGigA81OZAGFo_NWrxq8nLfhe5D5kP2Rw-_M3j_4i456-lUw_cPxBQhKdj06E]oak_box@y...[/url
Sent: Wednesday, January 14, 2004 10:51 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Voltage spikes and big loads...
Adrian,
One thing to remember with MOV's - You never know when
they've been blown until it's too late... They're
great for protecting circuits, but they only take so
may spikes before they blow out. And once they have
(in most of the MOV protected computer surge
protectors), you don't know.
Anyone know how to test one (short of hi-pot'ing it
<which could cause it to then burn out>)???
THE REAL QUESTION:
My real question was, what the experience is driving
relatively LARGE motor loads with a BS2.
I'm in the process of putting together a fair sized
robot platform, and expect to use some fairly hefty
motors to drive it - though still on the order of 6-12
volts.
I've played a little with driving a simple gearmotor,
and ordered H-bridge drivers for it. Before the BS2
had arrived, I hooked up a 555 timer circuit to try
driving the PWM function and see if I could control
the speed of the motor.
Under load, the noise from the motor was enough to
completely disrupt the 555 circuit.
Now, I'm aware of the standard practices of putting
the 3 cap's on the motors, and reverse bias diodes on
the driving transistors. But I'm suspicious that this
will only take care of so much.
I have no problem using separate voltage regulators
for the drive electronics vs. the logic/controller
circuitry. And I'm getting ready to order
opto-isolators if I need them.
How much will the capacitors take care of, and at what
point do you have to go to totally isolated circuits
with separate power supplies?
Thanks!
J.
--- Adrian <adrian650@y...> wrote:
> As there have been few replies,
>
> I looked into the issue of frying-stamps as I'm
> using
> one in an autootive environment where higher voltage
> transitions may occur if regulator fails, HT noise
> etc
> etc. It appeared to me that MOVs were a possible
> solution. At a given voltage they become open
> circuit
> and will pass a substantial current for a short
> time.
>
> From the data sheet you need to choose one that is
> closed at the normal voltage but opens at a voltage
> above normal but below the STAMP regulator failure
> voltage - using an external linear regulator might
> give more latitude here.I understand that a MOV
> alone
> will suppress a tranisent and suspect that they will
> survive long enough to blow a quick-blow fuse in
> series with PSU.
>
> Adrian
>
>
> =====
> -
> *********************************************
>
>
________________________________________________________________________
> Yahoo! Messenger - Communicate instantly..."Ping"
> your friends today! Download Messenger Now
> http://uk.messenger.yahoo.com/download/index.html
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed.
> Text in the Subject and Body of the message will be
> ignored.
>
>
> Yahoo! Groups Links
>
> To visit your group on the web, go to:
> http://groups.yahoo.com/group/basicstamps/
>
> To unsubscribe from this group, send an email to:
> basicstamps-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject to:
> http://docs.yahoo.com/info/terms/
>
>
__________________________________
Do you Yahoo!?
Yahoo! Hotjobs: Enter the "Signing Bonus" Sweepstakes
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To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
Yahoo! Groups Links
To visit your group on the web, go to:
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To unsubscribe from this group, send an email to:
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