Digitally-controlled pot?

[Dungeon Dave]

Further to my last post about having a dimmer circuit (using the Bowden
circuit mentioned previously), next stage is to try to replace to 50K pot
with something more remotely controllable.

The idea is that although I can manually turn up/down the dimmer, by
having it controllable from a variety of sources I can replace manual
control with either computer-based or timer-based (or a combination of
all three) - so I'm looking at something I can ideally feed in a
"increase" or "decrease" signal and it'll increment/decrement the pot
driving the Bowden circuit.

Is this feasible?

Lastly, I wouldn't mind trying to do the same circuit idea but for mains
lamps - like the Halogen dimmer circuits - to drive a set of Haloge
spotlights used for lounge uplighters. I once attended a conference in
which a rocker switch near the door was used to toggle on/off the lights,
but holding down the switch would increase/decrease light intensity,
allowing a light level dark enough to permit a projector to be used for
presentations but still with enough light that attendees could scribble
notes. The same switch was located over near the speaker's stand, as well
as near another control panel - it was clear that the circuitry lay not
behind the switch itself (as with some conventional rotary dimmers) but
elsewhere with several switches all paralleled up to provide the same
control from different locations.

Again.. should I hunt around for a circuit to do this, or is there some
off-the-shelf idea that I could utilise?

 

[Dungeon Dave]

Is there some reason that you want to design and build this yourself?
Or

would you be satisfied with an X10, or DMX lighting controls?

No reason whatsoever - I was looking for an off-the-shelf system,
thinking someone would spam me with "have you tried Arglebargle
controllers from lighting-gizmos.info" or "try this diagram from
www.youcanbuildityourself.projects" but over in the other thread it seems
a PCW dimmer ought to do the trick, so was looking at building one.

I think my requirements are more complex than a simple plug-in-and-go-
LED-driver box idea, but less than full-blown theatre-class dimmer packs.

I did a veroboard layout for the Bowden circuit in readiness; I know it's
not that difficult to construct but before I take the plunge, I don't
want to find I could have just blown £20 or so on something that does
everything I need it to (with cannibalisation tweaking).

 

[Dungeon Dave]

Is there some reason that you want to design and build this yourself?

Or would you be satisfied with an X10, or DMX lighting controls?

No reason whatsoever - I was looking for an off-the-shelf system,
thinking someone would spam me with "have you tried Arglebargle
controllers from lighting-gizmos.info" or "try this diagram from
www.youcanbuildityourself.projects" but over in the other thread it
seems a PCW dimmer ought to do the trick, so was looking at building
one.

I think my requirements are more complex than a simple
plug-in-and-go-LED-driver box idea, but less than full-blown
theatre-class dimmer packs.

I did a veroboard layout for the Bowden circuit in readiness; I know
it's not that difficult to construct but before I take the plunge, I
don't want to find I could have just blown £20 or so on something that
does everything I need it to (with cannibalisation tweaking).

 

[Eeyore]

Further to my last post about having a dimmer circuit (using the Bowden
circuit mentioned previously), next stage is to try to replace to 50K pot
with something more remotely controllable.

The idea is that although I can manually turn up/down the dimmer, by
having it controllable from a variety of sources I can replace manual
control with either computer-based or timer-based (or a combination of
all three) - so I'm looking at something I can ideally feed in a
"increase" or "decrease" signal and it'll increment/decrement the pot
driving the Bowden circuit.

Is this feasible?

I don't know the 'Bowden circuit' but digitally controlled pots may not
sustain the voltage requirements of many typical dimmer circuits.

Graham

 

[Dungeon Dave]

I don't know the 'Bowden circuit' but digitally controlled pots may
not sustain the voltage requirements of many typical dimmer circuits.

Graham

ah, my mistake:

http://ourworld.compuserve.com/homepages/Bill_Bowden/page6.htm#dimmer.gif

There's 12V across 52K (50K of a pot + 2x 1K). I did some calculations
last night, thinking that standard quarter-watt resistors may not be up
to it... and that entire series chain has about a quarter of a milliamp
running through it, so I'm guessing most DIPs can handle that oompf.

However, I'm on Brendan's link at the moment, sussing out the differences
between each option (hell- there's so many to choose from!).

Guess I'll google around for a suitable circuit that contains one of
these driving a 50K digi pot.