[sdiy] (OT) help with DEC branded relays - update

[Benjamin Riggs]

Ok, now I shaved the top of the relay off to see its operation, it seems it
is having a lot of trouble pulling the contacts in. I could see them pulling
in, but real slow. The contacts themselves are in a pretty bad state, so I
decided it best to try and remove it.

I got it off ok, I used a bit of acetone, softened the glue up (or the
plastic of the relay) enough for it to snap off. The pin spacing is pretty
standard, I managed to find a relay on RS Australia with the same pin
spacing 10A rated AgNi contacts (Finder 44 series relay). PCB sockets are
available for them too, so I might get one of them too in case it fails
again. If only my car wasn't failing me, (so my finances have taken a dive),
I'd put the order in ASAP.

On a side note, the advertising blurb for the amplifier stated it used gold
contacted relays throughout. Dunno where the gold went in this one?

Thank you all very much for the advice and feedback on something that was
off topic, it was all very helpful. Of course, any further comment is
appreciated, the amplifier holds a bit of sentimental value so I want to get
it %100 again.

Ben.

-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of harrybissell
Sent: Thursday, 30 June 2005 11:25 AM
To: The Peasant
Cc: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] (OT) help with DEC branded relays

I agree...  BIG mercury relay would be perfect for small AND
large signals... unless you have enough current to start an arc
like the old Ignitron tubes !!!

RoHS be dammed, eh ???

H^) harry

The Peasant wrote:

> Quoting Harry Bissell Jr <harrybissell at prodigy.net>:
> >
> > A wide current range relay should be unnecessary as
> > the
> > current will 'sometimes' be quite high and this will
> > maintain the relay contacts.  (so - disagree here ;^)
>
> Well, for a small NAD amplifier, you are probably correct. I really don't
like
> relays in the speaker circuit, although the speaker must be protected
somehow.
> However, I do have some big mercury types that should work great!
>
> > Most relays are specified for switching current, not
> > carry current.  This relay is not required to switch
> > while the signal is applied.  We can also look at the
> > duty cycle of those high current peaks.  If they were
> > 10% of the time, you could multiply the actual current
> > by the square root of the actual duty cycle and get
> > the rating you require. The relay contact could be
> > rated at
> > roughly .316 of the applied current (a one amp relay
> > could carry 3 amps at 10% duty).  Real crest factors
> > are MUCH less...
> >
> > ...unless they were mastered for maximum loudness :^P
>
> Thanks for the clarification, Harry!
>
> Take care,
> Doug
> ______________________
> The Electronic Peasant
>
> www.electronicpeasant.com