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design | replace pot on motor controller

There are 3 messages in this thread.

You are currently looking at messages 0 to 3.

replace pot on motor controller - Craig - 2008-03-10 01:46:00

I have a PWM motor controller that has a 10K pot to adjust the speed.
I have removed the pot and am wanting to use a 0-5 vdc analog signal
to change the speed.  Hooked up the 0-5 vdc signal in place of the pot
and the control is backwards i.e. 0 = 100% and 5 = 0%.

What could I add to change this?



Re: replace pot on motor controller - hrh1818 - 2008-03-10 11:01:00

On Mar 10, 12:46 am, Craig <craigswi...@hotmail.com> wrote:
> I have a PWM motor controller that has a 10K pot to adjust the speed.
> I have removed the pot and am wanting to use a 0-5 vdc analog signal
> to change the speed.  Hooked up the 0-5 vdc signal in place of the pot
> and the control is backwards i.e. 0 = 100% and 5 = 0%.
>
> What could I add to change this?

Take your 0 to 5 volt signal and feed it into one input of an
inverting amplifier that has two inputs. Feed a -5 VDC  signal into
the other input.  Now when your input signal is 0 the output of the
inverting amplifier is +5 VDC. And when your input signal is +5 VDC
the output of your inverting amplifier is 0 VDC.

Howard

Re: replace pot on motor controller - Craig - 2008-03-10 13:11:00

On Mar 10, 9:01=A0am, hrh1818 <hr...@att.net> wrote:
> On Mar 10, 12:46 am, Craig <craigswi...@hotmail.com> wrote:
>
> > I have a PWM motor controller that has a 10K pot to adjust the speed.
> > I have removed the pot and am wanting to use a 0-5 vdc analog signal
> > to change the speed. =A0Hooked up the 0-5 vdc signal in place of the pot=

> > and the control is backwards i.e. 0 =3D 100% and 5 =3D 0%.
>
> > What could I add to change this?
>
> Take your 0 to 5 volt signal and feed it into one input of an
> inverting amplifier that has two inputs. Feed a -5 VDC =A0signal into
> the other input. =A0Now when your input signal is 0 the output of the
> inverting amplifier is +5 VDC. And when your input signal is +5 VDC
> the output of your inverting amplifier is 0 VDC.
>
> Howard

Thank you