Chattering relay - RC Bot
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Posts: 46,084
I'm playing with my 1st RC Bot, its a sickly little thing, but I had to
start somewhere.
Everything is working so far, with the exception of the relays I'm using to
turn the gear reduced motors on and off. If they are under too much load
(like rapidly reversing direction) they seem to 'shut off' and back on a
couple of times a second until the load is reduced.
Its too late to change them now, I might as well start over if that's the
case. Everything worked fine on the bench, but when I drove it, the
problem developed. 1st lesson in building a robot, test it before you
finish it!
I'm using 5 volts to turn the coil on and off, and I'm switching about 20
volts DC. The load is less than 1 amp, and the relay is rated for 3 amps.
Any ideas? Anything additional I can do to the current setup to save it?
My stamp isn't going to stay in this one very long anyway, but I would like
to have a little fun with it first!
-John
start somewhere.
Everything is working so far, with the exception of the relays I'm using to
turn the gear reduced motors on and off. If they are under too much load
(like rapidly reversing direction) they seem to 'shut off' and back on a
couple of times a second until the load is reduced.
Its too late to change them now, I might as well start over if that's the
case. Everything worked fine on the bench, but when I drove it, the
problem developed. 1st lesson in building a robot, test it before you
finish it!
I'm using 5 volts to turn the coil on and off, and I'm switching about 20
volts DC. The load is less than 1 amp, and the relay is rated for 3 amps.
Any ideas? Anything additional I can do to the current setup to save it?
My stamp isn't going to stay in this one very long anyway, but I would like
to have a little fun with it first!
-John
Comments
john@l... writes:
> I'm using 5 volts to turn the coil on and off, and I'm switching about 20
> volts DC. The load is less than 1 amp, and the relay is rated for 3 amps.
Exactly how are you energizing the relay coil? Are you powering the coil with
5V directly from the stamp?
Or is the stamp driving a transistor, that grounds the coil?
Also, does your relay coil have a doide across it (cathdoe end to the + side
of coil)?
Is the relay being driven from the stamp 5v power supply or auxillary voltage
source?
Please give details on exactly how your relay is wired / interfaced to the
stamp....
[noparse][[/noparse]Non-text portions of this message have been removed]
Here's what may be happening... When your motors experience heavy load,
they draw more current from your batteries. This is probably reducing the
available battery voltage to the point where the relay coils can no longer
hold the contacts closed. Once the relay contacts open, the motor is no
longer loading down the battery voltage so the voltage goes back up and the
relays can turn on once again. Now the motors are back in the circuit and
the battery voltage goes back down....
Another possibility is that the battery voltage is going low enough that the
Stamp power is going below 5 volts and the Stamp is resetting and starting
your program over once the voltage returns to an adequate level. It sounds
more like the former, though.
Try monitoring the battery voltage when the motors are heavily loaded to see
what happens. If you are running the Stamp and the motors from the same
battery, you can try temporarily running the Stamp from a separate 9V
battery to see if that makes a difference. At least then you know that the
Stamp has adequate voltage to run properly.
If the problem isn't the Stamp resetting you have a few choices... Increase
the current capacity of the battery, reduce the maximum current drawn by the
motors, or avoid the operating condition that puts so much load on the
motors.
Another possibility... a bad connection to the battery may be causing a high
resistance, which would result in a voltage drop under load. If you find
that the voltage at the relay coils does dip enough to cause the relay
contacts to open, check the voltage at the battery pack under the same
conditions. If it is nearly the same, voltage drops in the wiring aren't
the problem. If it is significantly higher at the battery, you need to
check for high resistance in the wiring and connections between the battery
and the relays/motors. Adequate wire size and good connections should not
allow much voltage drop from the batteries to the loads they power (motors
in this case).
Hope this helps,
Randy
www.glitchbuster.com
> I'm playing with my 1st RC Bot, its a sickly little thing, but I had to
> start somewhere.
>
> Everything is working so far, with the exception of the relays I'm using
to
> turn the gear reduced motors on and off. If they are under too much load
> (like rapidly reversing direction) they seem to 'shut off' and back on a
> couple of times a second until the load is reduced.
>
> Its too late to change them now, I might as well start over if that's the
> case. Everything worked fine on the bench, but when I drove it, the
> problem developed. 1st lesson in building a robot, test it before you
> finish it!
>
> I'm using 5 volts to turn the coil on and off, and I'm switching about 20
> volts DC. The load is less than 1 amp, and the relay is rated for 3 amps.
>
>
> Any ideas? Anything additional I can do to the current setup to save it?
>
> My stamp isn't going to stay in this one very long anyway, but I would
like
> to have a little fun with it first!
>
>
> -John
>
>
>
> 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.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
voltage dropping below the level required to hold the relay on. Also it
could be noise feeding back into the micro causing erratic control to the
relay. Check your ground connections and relay control lines for cold
solder joints. An oscilloscope is very helpful for finding this kind of
problem because a meter is too slow to detect some of these kinds of
problems.
jim
http://www.geocities.com/jimforkin2003/
Original Message
From: John Walton [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=1SvIKJwK9nBcKgcIG6BrNeueP8I7Fn-rSKQNF8j5mDf8lJXIHqWXOjccrqmCPR0_k5qHTiFG40lCZA]john@l...[/url
Sent: Sunday, July 27, 2003 11:44 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Chattering relay - RC Bot
I'm playing with my 1st RC Bot, its a sickly little thing, but I had to
start somewhere.
Everything is working so far, with the exception of the relays I'm using to
turn the gear reduced motors on and off. If they are under too much load
(like rapidly reversing direction) they seem to 'shut off' and back on a
couple of times a second until the load is reduced.
Its too late to change them now, I might as well start over if that's the
case. Everything worked fine on the bench, but when I drove it, the
problem developed. 1st lesson in building a robot, test it before you
finish it!
I'm using 5 volts to turn the coil on and off, and I'm switching about 20
volts DC. The load is less than 1 amp, and the relay is rated for 3 amps.
Any ideas? Anything additional I can do to the current setup to save it?
My stamp isn't going to stay in this one very long anyway, but I would like
to have a little fun with it first!
-John
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.
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
details, but I'm at work now... I'll give the suggestions a try, if I
can't narrow it down I'll post more.
You guys are great.
-John
Original Message
From: Jim Forkin [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=gbSv2qzxHjfPzn_Je4z_VSBpHbchzKV-hpdBCJJTURzZmVCKQsX2-AKCkPnkMkO0z_dEsxVj]jjf@p...[/url
Sent: Monday, July 28, 2003 7:56 AM
To: basicstamps@yahoogroups.com
Subject: RE: [noparse][[/noparse]basicstamps] Chattering relay - RC Bot
usually this type of problem is not caused by the load, but by the
control
voltage dropping below the level required to hold the relay on. Also it
could be noise feeding back into the micro causing erratic control to
the
relay. Check your ground connections and relay control lines for cold
solder joints. An oscilloscope is very helpful for finding this kind of
problem because a meter is too slow to detect some of these kinds of
problems.
jim
http://www.geocities.com/jimforkin2003/
Original Message
From: John Walton [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=crrkfUYA02KH6aBhrVxhsMc2mheZsw8Y2P0AXJbDkjUtQ65KF99AhZti5CMM0HTFBs_1FGZlVQo]john@l...[/url
Sent: Sunday, July 27, 2003 11:44 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Chattering relay - RC Bot
I'm playing with my 1st RC Bot, its a sickly little thing, but I had to
start somewhere.
Everything is working so far, with the exception of the relays I'm using
to
turn the gear reduced motors on and off. If they are under too much
load
(like rapidly reversing direction) they seem to 'shut off' and back on a
couple of times a second until the load is reduced.
Its too late to change them now, I might as well start over if that's
the
case. Everything worked fine on the bench, but when I drove it, the
problem developed. 1st lesson in building a robot, test it before you
finish it!
I'm using 5 volts to turn the coil on and off, and I'm switching about
20
volts DC. The load is less than 1 amp, and the relay is rated for 3
amps.
Any ideas? Anything additional I can do to the current setup to save
it?
My stamp isn't going to stay in this one very long anyway, but I would
like
to have a little fun with it first!
-John
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject
and
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and Body of the message will be ignored.
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I'm not sure if this has been suggested, or if your
problem has been solved, but capacitors may be a cheap
solution.
Whenever you have relays, motors, batteries, and
control electronics, you have voltage sags and
momentery drop-outs. I would suggest "decoupling the
hell" out of your different voltages. For your 5V
line, I'd put a 4,700uF, 10V cap in parallel with it.
For the 20V source, I'd put a 2,200uF, 25V cap on it.
Big surplus caps are cheap and can make a huge
difference durring transient conditions. Unless your
battery or power supply can deliver 5,000AH, a large
cap can significantly lower the impeadance of your
supply rail.
I see lots of threads about "chattering" this, or
"pulsing" that. Then I see recommendations of 1uF or
maybe 47uF caps to help. In professional applications
where PCBs are used and low impeadance power supplies
are in place, this may be fine. But for point-to-point
construction, or proto-boards, I'd highly recommend
large caps (i.e. 1,000uF to 10,000uF @ 20% higher
voltage than what's being filtered). Unless timing is
being set, large caps on power supply circuits
generally can never hurt.
Regards,
Dr. Diode
--- John Walton <john@l...> wrote:
> Thanks for the replies everyone, I know I owe some
> of you some more
> details, but I'm at work now... I'll give the
> suggestions a try, if I
> can't narrow it down I'll post more.
>
> You guys are great.
>
>
> -John
>
>
>
Original Message
> From: Jim Forkin [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=MP3YWeaOX4df7p2iBSchr25ToBFVJT21oKnuzej6h8wom5ntdBAG6ZBRiCAgeiMgNv72eJjB]jjf@p...[/url
> Sent: Monday, July 28, 2003 7:56 AM
> To: basicstamps@yahoogroups.com
> Subject: RE: [noparse][[/noparse]basicstamps] Chattering relay - RC Bot
>
> usually this type of problem is not caused by the
> load, but by the
> control
> voltage dropping below the level required to hold
> the relay on. Also it
> could be noise feeding back into the micro causing
> erratic control to
> the
> relay. Check your ground connections and relay
> control lines for cold
> solder joints. An oscilloscope is very helpful for
> finding this kind of
> problem because a meter is too slow to detect some
> of these kinds of
> problems.
>
> jim
> http://www.geocities.com/jimforkin2003/
>
>
>
Original Message
> From: John Walton [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=tHa9MN7ILO8Ot3fYMfhUb_dU5_5R_8pd2HN7ML3YHjXPQXZaXSmCxJHgMam6n2Jn-tqIo_go]john@l...[/url
> Sent: Sunday, July 27, 2003 11:44 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Chattering relay - RC Bot
>
>
> I'm playing with my 1st RC Bot, its a sickly little
> thing, but I had to
> start somewhere.
>
> Everything is working so far, with the exception of
> the relays I'm using
> to
> turn the gear reduced motors on and off. If they
> are under too much
> load
> (like rapidly reversing direction) they seem to
> 'shut off' and back on a
> couple of times a second until the load is reduced.
>
> Its too late to change them now, I might as well
> start over if that's
> the
> case. Everything worked fine on the bench, but when
> I drove it, the
> problem developed. 1st lesson in building a robot,
> test it before you
> finish it!
>
> I'm using 5 volts to turn the coil on and off, and
> I'm switching about
> 20
> volts DC. The load is less than 1 amp, and the
> relay is rated for 3
> amps.
>
>
> Any ideas? Anything additional I can do to the
> current setup to save
> it?
>
> My stamp isn't going to stay in this one very long
> anyway, but I would
> like
> to have a little fun with it first!
>
>
> -John
>
>
>
> 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.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
>
> 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.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
>
>
>
>
> 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.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
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I meant 5,000mAH (5AH) - 5,000AH would be for welding.
--- PH <drdiode2002@y...> wrote:
> Hi John,
>
> I'm not sure if this has been suggested, or if your
> problem has been solved, but capacitors may be a
> cheap
> solution.
>
> Whenever you have relays, motors, batteries, and
> control electronics, you have voltage sags and
> momentery drop-outs. I would suggest "decoupling the
> hell" out of your different voltages. For your 5V
> line, I'd put a 4,700uF, 10V cap in parallel with
> it.
> For the 20V source, I'd put a 2,200uF, 25V cap on
> it.
> Big surplus caps are cheap and can make a huge
> difference durring transient conditions. Unless your
> battery or power supply can deliver 5,000AH, a large
> cap can significantly lower the impeadance of your
> supply rail.
>
> I see lots of threads about "chattering" this, or
> "pulsing" that. Then I see recommendations of 1uF or
> maybe 47uF caps to help. In professional
> applications
> where PCBs are used and low impeadance power
> supplies
> are in place, this may be fine. But for
> point-to-point
> construction, or proto-boards, I'd highly recommend
> large caps (i.e. 1,000uF to 10,000uF @ 20% higher
> voltage than what's being filtered). Unless timing
> is
> being set, large caps on power supply circuits
> generally can never hurt.
>
> Regards,
> Dr. Diode
>
> --- John Walton <john@l...> wrote:
> > Thanks for the replies everyone, I know I owe some
> > of you some more
> > details, but I'm at work now... I'll give the
> > suggestions a try, if I
> > can't narrow it down I'll post more.
> >
> > You guys are great.
> >
> >
> > -John
> >
> >
> >
Original Message
> > From: Jim Forkin [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=slWk6NZyjkFFF7Rg3J3sIgJQyV4H6nVGZBVFPKcmX8FRcGe31nCkJg2JM8YyuI-HEvqn8Jxecw]jjf@p...[/url
> > Sent: Monday, July 28, 2003 7:56 AM
> > To: basicstamps@yahoogroups.com
> > Subject: RE: [noparse][[/noparse]basicstamps] Chattering relay - RC
> Bot
> >
> > usually this type of problem is not caused by the
> > load, but by the
> > control
> > voltage dropping below the level required to hold
> > the relay on. Also it
> > could be noise feeding back into the micro causing
> > erratic control to
> > the
> > relay. Check your ground connections and relay
> > control lines for cold
> > solder joints. An oscilloscope is very helpful
> for
> > finding this kind of
> > problem because a meter is too slow to detect some
> > of these kinds of
> > problems.
> >
> > jim
> > http://www.geocities.com/jimforkin2003/
> >
> >
> >
Original Message
> > From: John Walton [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=sr7Hbc3CcANpaigw-6E9UgQwj-BLBf1ad7cFCSh8LFPcaB7GDx7a6bFDMoSo9sCj8aSA3r_791ix]john@l...[/url
> > Sent: Sunday, July 27, 2003 11:44 PM
> > To: basicstamps@yahoogroups.com
> > Subject: [noparse][[/noparse]basicstamps] Chattering relay - RC Bot
> >
> >
> > I'm playing with my 1st RC Bot, its a sickly
> little
> > thing, but I had to
> > start somewhere.
> >
> > Everything is working so far, with the exception
> of
> > the relays I'm using
> > to
> > turn the gear reduced motors on and off. If they
> > are under too much
> > load
> > (like rapidly reversing direction) they seem to
> > 'shut off' and back on a
> > couple of times a second until the load is
> reduced.
> >
> > Its too late to change them now, I might as well
> > start over if that's
> > the
> > case. Everything worked fine on the bench, but
> when
> > I drove it, the
> > problem developed. 1st lesson in building a
> robot,
> > test it before you
> > finish it!
> >
> > I'm using 5 volts to turn the coil on and off, and
> > I'm switching about
> > 20
> > volts DC. The load is less than 1 amp, and the
> > relay is rated for 3
> > amps.
> >
> >
> > Any ideas? Anything additional I can do to the
> > current setup to save
> > it?
> >
> > My stamp isn't going to stay in this one very long
> > anyway, but I would
> > like
> > to have a little fun with it first!
> >
> >
> > -John
> >
> >
> >
> > 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.
> >
> >
> > Your use of Yahoo! Groups is subject to
> > http://docs.yahoo.com/info/terms/
> >
> >
> >
> > 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.
> >
> >
> > Your use of Yahoo! Groups is subject to
> > http://docs.yahoo.com/info/terms/
> >
> >
> >
> >
> >
> >
> > 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.
> >
> >
> > Your use of Yahoo! Groups is subject to
> > http://docs.yahoo.com/info/terms/
> >
> >
>
>
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