John Fields wrote:
On Thu, 08 Sep 2011 21:56:25 -0400, Jamie
t wrote:
John Fields wrote:
On Thu, 08 Sep 2011 11:23:56 -0400, Jamie
et wrote:
Don't be anal, they make relays that will do AD/DC because they have a
diode imbedded in them.
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"Embedded."
Link?
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The voltage ratings are the same. The coil is
actually of DC type..
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If you're saying that half-wave rectified 12VAC will cause the
armature of a relay with a 12VDC coil to close, instead of chatter,
then I'd have to ask for proof since I have empirical evidence which
refutes your assertion.
Years ago, Larkin and I had the same argument here.
He took your position and lost the argument.
Well, then he lost unfairly.
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Instead of blathering on about something of which you obviously have
little knowledge, why not try it?
That is, get a few relays with DC coils, drive their coils with
half-wave rectified AC, and post back with the results.
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Never heard of core hysteresis?
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Sure, but for relays it's usually defined as the difference between
the must-make and must-break voltage instead of this:
http://www.google.com/imgres?imgurl=...9QEwAQ&dur=468
Now we both know!
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They also have relays with shunt diodes built into
them, for those you need to insure the polarity is correct and are
strictly DC only.
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What does that have to do with driving DC coil relays with rectified
AC, or driving AC coil relays with DC?
From my experience, those diodes are used in order to return the
coil's inductive turn-off transient to the positive supply in order to
keep E = LdI/dT from ruining a relay driver's day, and to save the
user the expense of an extra part and the PCB real estate needed for
its implementation.
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We also deal with solenoids to operate in the same manner..
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Elaborate, please?
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Why?. You don't understand why, I guess?
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Well, although a case might be made for:
.AC---[DIODE]--+-------+
. | |K
. [COIL] DIODE
. | |
.AC-------------+-------+
I've never heard of a DC solenoid being converted to AC by using a
shunt diode, have you?
If so, why not give us the benefit of your knowledge by elaborating on
the subject?
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Scroll down and read about AC coils, I am sure if you're looking for
some more detailed information you can find it, but this will explain
some of the differences.
http://www.ehow.com/about_6498402_di...elay-coil.html
Jamie
I was going to make a whole page for you to read, but I know how you
carry on with JL, I won't be another one of your imaginary conquest.
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Aw... Poor baby.
Afraid of making and having to own up to an error, are you? 
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Not saying that don't know what your doing but you tend to over look
a few things that have been done in the field over the years.
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Like what, the development of latching relays with infinite gain?
No error, you're the one with egg on the face loser, and this will be
my last to you. I will not be another JL stick for you to crack your
false sense of victory with.
http://relays.te.com/appnotes/app_pdfs/13c3250.pdf
Just because you haven't seen it or think it shouldn't be done means
every one else should bend over to your rule? Sorry sucker, this is why
people move on and those like yourself are left holding the bag.
And while your reading that doc, if you even do, the comment about
unfiltered DC where the armature might experience movement, they don't
say it will. That is because it depends on the mechanical design of the
relay and type of system in place.
Further more, I guess you've never seen the old trick of operating a
small DC relay with half wave to force the unit to slightly vibrate, not
enough to actually see it how ever, when doing this, you could force the
contact surface to keep themselves cleaner and thus cheap relays would
be used to pass reference signals through. This would be evident over
time from apparent ware on the contacts from mechanical movement and no
arc which would otherwise do the wetting process via the plasma process.
By and have a good life..
Jamie