Re: Humidity sensor - Electronics expert required!

[Julian Driver <julian@xxxxxxx>]

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Thanks Keith, that's a great help. Unfortumately the datasheet only
seems to exist in hard copy and had to be collected from Farnell trade
counter. When I'm back from my hols I will convert it to a pdf for
anybody who wants it.

In message <NBBBLLKOOHNLKHBANMANAEOGNDAA.keith.doxey@xxxxxxx>,
Keith Doxey <keith.doxey@xxxxxxx> writes
>    Hi Julian,
>
>    The 47uF capacitor is probably to provide some smoothing to the
>    output so
>    you dont get sudden spikes or drops in the reading. Any permanent
>    change in
>    the output will be accurately shown within a couple of seconds. The
>    resistor
>    will be to leak the charge away from the capacitor otherwise the
>    reading may
>    never fall to zero!
>
>    Think of it as an averaging circuit. It will hide any sudden
>    changes but
>    will track the trend giving a truer reading overall.
>
>    You could probably omit them but then you would have to write your
>    program
>    to take spurious readings into account.
>
>    The above is pure speculation based on your description......a link
>    to the
>    datasheet would have been nice :-)
>
>    Keith
>
>
>
>
>
>    -----Original Message-----
>    From: Julian Driver [mailto:julian@xxxxxxx]
>    Sent: 29 August 2000 19:05
>    To: ukha_d@xxxxxxx
>    Subject: [ukha_d] Humidity sensor - Electronics expert required!
>
>
>    I am all set up to connect a humidity sensor to my Homevision. It
>    has
>    connections for +5v, ground and an output voltage of 1 to 3v
>    proportional to humidity. So far so good.
>
>    The measurement circuit in the datasheet however has the output
>    connected to ground via a 47 microfarad capacitor and a 100K
>    resistor
>    connected in parallel. My question is What do these do, and do I
>    need
>    them with HV?
>
>    (I tried to draw it but the result in ASCII is too embarrassing for
>    words.)
>    --
>    Julian Driver
>
>
>
>
>
>

--
Julian Driver