PROBLEM with SERVO
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Posts: 46,084
Im trying to get a CIRRUS 21BB servo to work on batteries ; I am NOT using a
servo controller like the ferretronics FT - 639. Instead I am using the stamp
with the following code to send pwm signals to the control line of the servo.
servo:
pulsout 15,1200
pause 20
goto servo
this sends a 2.4ms pulse at a little more than 50 (53) Hz.
Now the problem is this:
When i used a good power supply to give 4.8V it(the servo) was running fine. I
then wanted to switch to batteries so i used 3 D size (the big ones) 1.5V in
series to create around 4.5v. The servo would just settle into one position and
refuse to budge. For any given control signal width .
I monitored the potential drop that the battery had when the control signal was
being sent . the battery is sturdy and giving a good 4.4v.
This is baffling. I thought it was the batteries but the batteries are providing
a good stable voltage supply. Please help.
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servo controller like the ferretronics FT - 639. Instead I am using the stamp
with the following code to send pwm signals to the control line of the servo.
servo:
pulsout 15,1200
pause 20
goto servo
this sends a 2.4ms pulse at a little more than 50 (53) Hz.
Now the problem is this:
When i used a good power supply to give 4.8V it(the servo) was running fine. I
then wanted to switch to batteries so i used 3 D size (the big ones) 1.5V in
series to create around 4.5v. The servo would just settle into one position and
refuse to budge. For any given control signal width .
I monitored the potential drop that the battery had when the control signal was
being sent . the battery is sturdy and giving a good 4.4v.
This is baffling. I thought it was the batteries but the batteries are providing
a good stable voltage supply. Please help.
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Yahoo! Mail Plus - Powerful. Affordable. Sign up now
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Comments
motors on 4 nicad batteries, but not on 4 NiMH batteries. I also could not
see any voltage drop using my volt meter. I think you have a signal problem.
I think the servos are drawing some amperage causing a spike that is messing
up your stamp.
is the stamp resetting? put a sound line before the servo command loop. See
if the sound plays continually. that will tell you if the stamp is resetting.
Did you try various filters on the stamp inputs, and high value caps to
filter out any wierd spikes?
Finally run your D cell batteries to the servo, and power the stamp from a
tottaly seperate source, that should really tell you if its the power supply
problem.
I myself run 4 C cell batteries on 2 wheel servos and the stamp and have
been lucky.
-Kerry
At 02:19 PM 12/9/02 -0800, you wrote:
>
>Im trying to get a CIRRUS 21BB servo to work on batteries ; I am NOT using
a servo controller like the ferretronics FT - 639. Instead I am using the
stamp with the following code to send pwm signals to the control line of the
servo.
>
>servo:
>
>pulsout 15,1200
>
>pause 20
>
>goto servo
>
>
>
>this sends a 2.4ms pulse at a little more than 50 (53) Hz.
>
>Now the problem is this:
>
>When i used a good power supply to give 4.8V it(the servo) was running
fine. I then wanted to switch to batteries so i used 3 D size (the big ones)
1.5V in series to create around 4.5v. The servo would just settle into one
position and refuse to budge. For any given control signal width .
>
>I monitored the potential drop that the battery had when the control signal
was being sent . the battery is sturdy and giving a good 4.4v.
>
>This is baffling. I thought it was the batteries but the batteries are
providing a good stable voltage supply. Please help.
>
>
>
>
>
>
>Do you Yahoo!?
>Yahoo! Mail Plus - Powerful. Affordable. Sign up now
>
>[noparse][[/noparse]Non-text portions of this message have been removed]
>
>
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Very respectfully, your obedient servant.
Kerry
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13795
607-775-1575
low-voltage situations. Just monitor the battery or processor voltage while
running the motor, then check your min value -- it should show you if the
voltage is being pulled down enough to reset the Stamp.
Original Message
> It sounds like a similar problem I had with motors. I could run my stamp
and
> motors on 4 nicad batteries, but not on 4 NiMH batteries. I also could not
> see any voltage drop using my volt meter. I think you have a signal
problem.
> I think the servos are drawing some amperage causing a spike that is
messing
> up your stamp.
> is the stamp resetting? put a sound line before the servo command loop.
See
> if the sound plays continually. that will tell you if the stamp is
resetting.
> Did you try various filters on the stamp inputs, and high value caps to
> filter out any wierd spikes?
> Finally run your D cell batteries to the servo, and power the stamp from a
> tottaly seperate source, that should really tell you if its the power
supply
> problem.
> I myself run 4 C cell batteries on 2 wheel servos and the stamp and have
> been lucky.