Re: Hacking fan controller

[Kevin Hawkins <yahoogroupskh@xxxxxxxxxxxxxx>]

So at one end the full resistance is inline and at the other it is
effectively zero ?  Does the pot look a very light duty ie electronic
circuitry type (few ma) or might it be beefier - handling a heavy
current / high voltage (mains even)   ?  If it's electronic circuitry
you may have some other options eg analog input , but otherwise as you
say you can switch in/out some equivalently rated resistors with
relays.  If you wire a few in series it would give you multiple speeds
eg 3 would give you six speeds plus full on/off.. ( 3 different values -
maybe divide original resistance by 8 and have 1x 2x and 4x ).  Look at
the linearity of the existing pot vs speed and also whether the pot is a
logarithmic or linear version.

You will need some software  'smarts' to sequence the relays in a binary
fashion eg a HomeVision macro via the HV outputs or C-Bus relays (slight
overkill)  via your gateway.

Paul Gale wrote:
> 3 but two at one end are soldered into the same track, so it's across
the entire adjustment renge.
>
> Paul.
>
>
>
>
>> -----Original Message-----
>> From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf
>> Of Kevin Hawkins
>> Sent: 29 January 2008 13:35
>> To: ukha_d@xxxxxxx
>> Subject: Re: [ukha_d] Hacking fan controller
>>
>> How many wires to the pot Paul - 2 or 3 ?
>>
>>     K
>>
>> Paul Gale wrote:
>>
>>> I've now got the fan and controller in the new Node0. At the
moment
>>> the fan is manually controlled or a simple on/off via CBus.
>>>
>>> I want to hack into the speed controller to give me a few
speed
>>> options. The speed of the fan in controlled by a 470K sliding
pot.
>>>
>> Can
>>
>>> I simply hack into this via a number of relays and provide my
own
>>> alternative resistances? Or might there be another way of
achieving
>>>
>> this?
>>
>>> Paul.
>>>
>>> [Non-text portions of this message have been removed]
>>>
>>>
>>>
>>
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