Substituting a digital pot for a mechanical pot in an AC vol

E

eljainc

Guest
Hello,

I have a question. I have been trying using a DS1867 digital
potentiometer in a circuit that will replace a mechanical
potentiometer of 250KOhm. The circuit/device that is uses the pot is
an AC voltage controller made by Radio Shack (cat 64-2054). When I
substitute the DS1867 digipot for the standard pot, the load is not
powered.

What might the problem be? I've now fried two of these Rad Shack
voltage controllers in attempt to test a digitally controlled pot. I
don't think the digipot was damaged. Is there another passive
component required in the circuit (cap or resistor) that needs to be
added?

Thanks
Mike
 
On Fri, 2 May 2008 07:26:44 -0700 (PDT), eljainc
<eljainc@sbcglobal.net> wrote:

Hello,

I have a question. I have been trying using a DS1867 digital
potentiometer in a circuit that will replace a mechanical
potentiometer of 250KOhm. The circuit/device that is uses the pot is
an AC voltage controller made by Radio Shack (cat 64-2054). When I
substitute the DS1867 digipot for the standard pot, the load is not
powered.

What might the problem be? I've now fried two of these Rad Shack
voltage controllers in attempt to test a digitally controlled pot. I
don't think the digipot was damaged. Is there another passive
component required in the circuit (cap or resistor) that needs to be
added?

Thanks
Mike
Click to expand...
The datasheet states that the voltages on the resistor terminals must
be between -5V and +5V - if any voltages are outside that range, you
will probably destroy the part.

You can get the full datasheet from http://www.maxim-ic.com



--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca
 
On Fri, 2 May 2008 11:23:59 -0700 (PDT), eljainc
<eljainc@sbcglobal.net> wrote:

Is there any AC motor controller that is computer controlled? (RS-232/
USB or TTL)

I guess the Maxim/Dallas parts won't work.
I see that even AD digipots wont work (some will work with 10-15VAC,
but not higher)
Click to expand...
---
Did you post a schematic of the radio shack circuitry? No.

Is it available on their web site? No.

Are we mind readers? No.

So how on earth do you expect anyone to give you any sort of
meaningful help if you don't even know how to ask a proper question
and tell us what it is you're up to?

Hmmm... I see you're posting form Google Groups, so never mind... that
explains it.

JF
 
"eljainc" <eljainc@sbcglobal.net> wrote in message
news:7fd7254e-74b2-4489-adaa-b31e42f6611c@l64g2000hse.googlegroups.com...
Is there any AC motor controller that is computer controlled? (RS-232/
USB or TTL)

I guess the Maxim/Dallas parts won't work.
I see that even AD digipots wont work (some will work with 10-15VAC,
but not higher)
Click to expand...

What kind of motor is it?

/bob
 
Is there any AC motor controller that is computer controlled? (RS-232/
USB or TTL)

I guess the Maxim/Dallas parts won't work.
I see that even AD digipots wont work (some will work with 10-15VAC,
but not higher)
 
The motor is an AC motor. I do not know the manufacturer of it.
However I have the following specs/attributes which may
help in choosing the controller for it.


single phase AC, 115VAC
1/7 HP at 4000 RPM
max current: 3.3A
150Watts
Permanent magnet motor
windings on the stator, but not rotor
two brushes, indicating that it is not an inductance motor
 
"eljainc" <eljainc@sbcglobal.net> wrote in message
news:41dbac1f-6dc3-4493-bf69-c4dfc980cb46@26g2000hsk.googlegroups.com...
The motor is an AC motor. I do not know the manufacturer of it.
However I have the following specs/attributes which may
help in choosing the controller for it.


single phase AC, 115VAC
1/7 HP at 4000 RPM
max current: 3.3A
150Watts
Permanent magnet motor
windings on the stator, but not rotor
two brushes, indicating that it is not an inductance motor
Click to expand...

The radio shack thingy controls the speed properly, right?

One possibility would be a motorized pot.

http://www.goldmine-elec-products.com/prodinfo.asp?number=G9962

This one probably won't work, but one of these might:

http://stores.ebay.com/familygate_ALPS-Motorpotis-motorized_W0QQfsubZ11

The other possibility is to measure the voltage that was across the pot
before you cut it out. If you post that information, it may well be that
someone can design a circuit that would let you control the control.

Regards,
Bob Monsen
 
Bob,

Thanks for the idea of the motorized pot. I should have thought of
that one. I will look to see
if I can find a 250K Ohm motorized pot.

As far as the voltage across the pot, I would have to measure
it when in operation. I can imagine that it runs from 0 to about
100VAC.



One possibility would be a motorized pot.

http://www.goldmine-elec-products.com/prodinfo.asp?number=G9962

This one probably won't work, but one of these might:

http://stores.ebay.com/familygate_ALPS-Motorpotis-motorized_W0QQfsubZ11

The other possibility is to measure the voltage that was across the pot
before you cut it out. If you post that information, it may well be that
someone can design a circuit that would let you control the control.

Regards,
Bob Monsen
Click to expand...
 
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