Re: [ST] headlight relay * CORRECTION *

[Neil Lindsey <Neil.Lindsey@xxxxxxx>]

Chris,

No such transistor driver exists in the headlight circuit, so that would
make the diode unnecessary for this application, assuming that it sits
across the relay's contacts.  Like I said, I would need a schematic to
comment further.

One thing does, however, require some further explanation.  It is not
uncommon for relays to include both normally-closed and normally-open
sets of contacts.  I believe that is the case here.  But, only the
normally-open contacts are being used. A simple relay with only
normally-open or normally-closed contacts would have 4 pins.  If it
includes the second sets of contacts there would be a total of 6.  The
existence of more pins would suggest additional components (like
diodes). The functionality would be reflected in the schematic.  So such
extra circuitry exists in the Triumph schematic, but the pin numbering
shown goes up to 8.  Pins 1 and 8 form the input contact pair, and pins
4 and 6 form the output side (where the load is connected).  Four pins
are unaccounted for.

These ARE simple relays (notwithstanding the apparent inclusion of said
diode).

Metering out the relays involved here could, however, be useful to
determine if there is difference.

Neil


----- Original Message ----- 
From: "Chris Harwood" <Chris@xxxxxxxxxxxxxxxxxx>
To: <ST@xxxxxxxxxxxxxx>
Sent: Tuesday, November 15, 2005 11:14 AM
Subject: Re: [ST] headlight relay * CORRECTION *


> The diode would not be for spark suppression.  They go across the coil
> to sink the back-emf when the relay is powered off.  If a transistor
is
> driving it this prevents the driver being destroyed.
>
> However, not all devices that look like relays are relays these days.
> Some have time delay components in them etc. for self-cancelling
> indicators, rear-screen heaters on cars and the like.
>
> I would strongly recommend that you don't plug anything new into the
> sockets unless you've buzzed all the device pins out with a multimeter
> or confirmed by the image on the side that it is the same
configuration
> as the good one you have.
>
> Chris Harwood
> 00 RS
>
> >>> Neil.Lindsey@xxxxxxx 15/11/2005 19:01:24 >>>
> You're right about relays being relatively simple, but if Marc had
> used
> a normally-closed relay instead of a normally-open variety the second
> low-beam would not have worked at all when the key was turned on with
> the dip switch in the low position.
>
> As for the comment about the diode, it is true that arc suppression is
> likely to be it's function, but there may more to it than that,
> particularly if it is associated with the input side, and not the load
> side.  I'd need to see exactly where it is placed in the relay and to
> study the schematic a bit more to comment further.
>
> There is also the possibility that the one than Marc tried is simply
> unable to handle the to current drawn by a high beam circuit, or
> perhaps
> even simply defective (though not likely).  If, for example, the
> contacts on the output side are overly resistive, the relay could get
> quite warm. Normally I would have expected the second low beam
> headlight
> to be noticeably dimmer, but maybe not.
>
> Unless, an EXACT replacement for the OEM relay can be identified FOR
> SURE, I don't think it's worth the effort.  The relay should be good
> for
> the life of the bike.
>
>
>
> ----- Original Message ----- 
> From: "Rick & Joyce" <rnjwes@xxxxxxxxxxx>
> To: <ST@xxxxxxxxxxxxxx>
> Sent: Tuesday, November 15, 2005 6:10 AM
> Subject: Re: [ST] headlight relay * CORRECTION *
>
>
> > First of all, I was wrong about the Bosch 0332 014 150 relay.
> > According to: http://tinyurl.com/9mc77 , it's a normally closed
> relay
> > with 2 output terminals. That means you could hook it up so current
> > flows when the switching current is off - not a good thing for a
> > headlight circuit!  A better Bosch application would be 0332 014 019
> > (12v, 30a, 4-terminal, normally open contacts - no room for error.
> >
> > So here's a corrected headlight relay list:
> > Bosch 0332 014 019
> > Hella 4RA 035 510 111
> > Wehrle 20 200100
> > Italamec 562.10
> > According to the same website, all the above are interchangeable.
> > We also have Emile's Hella 4RA 007 791-021.
> >
> >
> > Simplistically, a relay is a remotely-controlled electrical switch.
> > The relay's protection diode (think of it as an electronic
> > check-valve) prevents circuit-damaging electrical spikes when the
> > relay is switched.
> >
> > Let me add to Neil's response that you might check the relay
> amperage
> > rating too.  The Bosch one I listed is rated for 30 amps - more than
> > adequate for the 4-5 amp draw of a 55w low beam.
> >
> > FYI, here's a nice little tutorial on relays:
> > http://www.kpsec.freeuk.com/components/relay.htm
> >
> > --
> > Rick in Oregon
> > '01 Sprint ST
> >
> > _______________________________________________
> > Triumph Sprint ST/RS mailing list
> > Send list posts to ST@xxxxxxxxxxxxxx
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> >
>
>
>
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