Motor noise on video image
Greetings all,
I have a BSII on a board controlling two L293D circuits, which are
connected to four small pumps. In addition the BSII turns a small video
camera on and off as well. The board is powered by two 7.1 volt nicad
batteries, one battery powering the BSII and the two together powering
the motors and camera. When the motors are on they induce noise into the
video image. Who has suggestions for filtering out the noise from the
motors.
Regards, Theron Wierenga
I have a BSII on a board controlling two L293D circuits, which are
connected to four small pumps. In addition the BSII turns a small video
camera on and off as well. The board is powered by two 7.1 volt nicad
batteries, one battery powering the BSII and the two together powering
the motors and camera. When the motors are on they induce noise into the
video image. Who has suggestions for filtering out the noise from the
motors.
Regards, Theron Wierenga
Comments
chokes in both leads (or a common mode choke) and a capacitor across the
motor. The power supply should also be heavily bypassed. Often the motor
housing must be grounded as well, to suppress radiated noise...
> I have a BSII on a board controlling two L293D circuits, which are
>connected to four small pumps. In addition the BSII turns a small video
>camera on and off as well. The board is powered by two 7.1 volt nicad
>batteries, one battery powering the BSII and the two together powering
>the motors and camera. When the motors are on they induce noise into the
>video image. Who has suggestions for filtering out the noise from the
>motors.
Mike Hardwick, for Decade Engineering -- <http://www.decadenet.com>
Manufacturer of the famous BOB-II Serial Video Text Display Module!
Series chokes in the leads to the motors I assume, not the video card?
What size for a small 12 v. DC motor
drawing 250 ma?
Thanks, Theron
Mike Hardwick wrote:
> The most effective filtering for conventional DC motors is usually series
> chokes in both leads (or a common mode choke) and a capacitor across the
> motor. The power supply should also be heavily bypassed. Often the motor
> housing must be grounded as well, to suppress radiated noise...
>
> > I have a BSII on a board controlling two L293D circuits, which are
> >connected to four small pumps. In addition the BSII turns a small video
> >camera on and off as well. The board is powered by two 7.1 volt nicad
> >batteries, one battery powering the BSII and the two together powering
> >the motors and camera. When the motors are on they induce noise into the
> >video image. Who has suggestions for filtering out the noise from the
> >motors.
>
> Mike Hardwick, for Decade Engineering -- <http://www.decadenet.com>
> Manufacturer of the famous BOB-II Serial Video Text Display Module!
>
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noise problems from the blower motor, wipers and electric radiator fan. Our
fix was to wind some filters using the ferrite cores from Radio Shack. They
have various schemes for winding the wire depending on what you want to do.
Original Message
> The most effective filtering for conventional DC motors is usually series
> chokes in both leads (or a common mode choke) and a capacitor across the
> motor. The power supply should also be heavily bypassed. Often the motor
> housing must be grounded as well, to suppress radiated noise...
>
> > I have a BSII on a board controlling two L293D circuits, which are
> >connected to four small pumps. In addition the BSII turns a small video
> >camera on and off as well. The board is powered by two 7.1 volt nicad
> >batteries, one battery powering the BSII and the two together powering
> >the motors and camera. When the motors are on they induce noise into the
> >video image. Who has suggestions for filtering out the noise from the
> >motors.
the chokes and bypass cap as close to the motor terminals as possible.
Inductance isn't teribly critical. Use wire just big enough for motor stall
current, and wind as much as you can in a single layer on small cores. If
you use toroids, watch out for core saturation! Common mode choke windings
would be best in this case. That's where you wind a bifilar pair of wires
on a single core and connect them so motor current flows in opposite
directions, cancelling magnetic flux in the core. If you purchase chokes,
something in the 10~100uH range should be appropriate.
> Series chokes in the leads to the motors I assume, not the video
card? What size for a small 12 v. DC motor
>drawing 250 ma?
Mike Hardwick, for Decade Engineering -- <http://www.decadenet.com>
Manufacturer of the famous BOB-II Serial Video Text Display Module!