"Greg Mayman" bravely wrote to "Mike Ross" (24 Mar 04  08:16:00)
 --- on the heady topic of "{at}%^{at}#$%^ VEROBOARD"

 GM> But the spring that does the release, a motor? No way!

I agree, it is only storing mechanical energy. And a spring is more
like a component for example making up a resonnant tank circuit. A
resonnant tank will also push current into a circuit to do work in the
circuit resistance. Similarly a spring releases mechanical energy to
the moving parts to do work. So you are right about a spring not being
part of the motor.


 MR> Your explanation is excellent. The same applies to the magnetizing
 MR> threshold in a audio tape oxide particle but there is no positive
 MR> feedback in that either.

 GM> Hmmm... agreed about the lack of positive feedback, but they are
 GM> rather different effects.

Well, analogies can only go so far in describing an observed effect
simply because an analogy is not totally the same as the thing being
described. Now that's redundant!

However, I do understand the magnetic resistance decreases (and
conversely the magnetic conductivity increases) as the pole pieces
close the air gap. Where it gets interesting is that energy is stored
in the spring for later to help release the relay. So the closer air
gap allows more flux to get into the iron but the work energy done in
closing the gap is in fact stored for later use. That's a twist I
hadn't thought of, thanks.

I was thinking about relays the other day while waiting for the
elevator. As the elevator door opened I noticed both the up and down
arrows lit up together but it was going down. The elevator beside it
was going up and both its lights were off. Luckily the 3rd elevator
door didn't open to an empty shaft...!!! Today the elevator repairman
was busy working on the elevators. In the 19'th century all the
elevator logic was controlled by relays and they got stuck quite
regularly. Now why do modern computers without any moving parts in
their ALU's get stuck logic just like the relays in the early days of
elevators? Bizzare!

 Mike
 ****

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