Re: Swish discrete contol

["Alancc" <alan.cc@xxxxxxx>]

The diode across the relay coil is for protection against back EMF,
stops
the driver circuit being damaged when the relay turns off. This would
only
be used in a DC circuit otherwise the diode would present its self as a
near
short circuit for half of the AC cycle.

Alancc
----- Original Message -----
From: Robert Crawshaw <golcarbob@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Saturday, April 06, 2002 6:35 PM
Subject: Re: [ukha_d] Swish discrete contol


>
>
> > Hmm..
> >
> > The relay I was using has a coil rated at 230VAC :(
> >
> > That being said, now I think about it, the problem I had was not
when
the
> > coil was energised: this correctly closed the curtains.
> > The problem was when the thing was turned *off* at this point,
the relay
> > chattered like crazy, as if it didn't actually switch off
correctly.
>
>
> ermm  is this problem easily sorted with a diode across the coil
/??
> i seem to remember seeing this done quite a few times, cannot
remember
what
> the circuit was for though though :(
>
> Robert
Crawshaw                
http://www.golcarbob.com
>
> The internet has had no effect on my life wwwhatsoever.com
>
> I am Dyslexia of
Borg            Your
ass will be laminated
>
>

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