relays

As in a lever controlling the motion of something else -- like a break, for example, or a ratchet for another.

arrange

I agree that the lever, alone, is not a gain element. It can however be a control element like the relay, which can control larger power than is required to move the lever.

With a source of potential energy (like the weights of a pendulum clock), levers can be made to oscillate continuously so slong as the potential energy store holds out.

No they can't. *Escapement mechanisms* can be made to oscillate continuously, but they are not the same thing as a lever.

--
Guy Macon

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Actually, it doesn\'t.

JF

Escapement mechanisms generally employ levers in their construction though. It's the lever that controls the power moving through the larger mechanism. The lever is certainly oscillating in that setup.

For simpler, more obvious power control, a lever operated sluice gate is an example (and more akin to the general 'hydraulic' term invoked previously.

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=A0 =A0...Jim Thompson

Oh what about mechanical. The old fulcrum and lever.

George Herold

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=A0 =A0 =A0...Jim Thompson

opps good point!

In article , snipped-for-privacy@gmail.com=20 says...>=20

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=A0 =A0 =A0...Jim Thompson

Again, no gain. Does a transformer have gain?

--=20 Keith

Sure it does! Just like a common base has voltage gain, and a common collector has current gain (neither has >1 power gain), the lever has force gain one way, and distance gain the other way. :-)

(forcevoltage, distancecurrent.)

Cheers! Rich

On a sunny day (Thu, 13 Nov 2008 20:43:25 GMT) it happened Rich Grise wrote in :

Oh yes they do! Say a common base, delta Ic is nearly delta Ib, but P = I^2 . R, so with enough R you have power gain. That is the whole point of a transistor: power gain.

A lever is something totally different without external power input.

A simple example of real power gain is the tap you turn open.

According to

, "In 1835 Joseph Henry invented the relay, by which a weak current over long wires could operate a powerful local electromagnet. [4] [5]"

Hope This Helps! Rich

"D from BC" a écrit dans le message de news: snipped-for-privacy@4ax.com...

Nope. One gain nothing doing that.

-- Thanks, Fred.

You will note that I said "no power gain". A system with no power gain can't oscillate.

But both common-base and common-collector amps can have >1 power gain. Either can make a dandy oscillator.

Better luck tomorrow.

John

No power gain, can't build an oscillator [1]. But if you allow voltage gain, or current gain, sure. Or price gain.

John

[1] except magamps, which are transformers that have true power gain.

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rrange

=A0 =A0 =A0 =A0...Jim Thompson

Ok, then by the same argument, a lever has gain. I wouldn't call it=20 gain though.

--=20 Keith

arrange

Play with words, or numbers, all you like. I have been careful to specify "power gain."

John

Hey John,

Using your definitions, a mechanical valve can have power gain, yes? That'd be an awfully early form of a gain element.

I agree that a simple level doesn't have power gain.

---Joel

OK, please post the equation for the power gain of a latching relay.

John

A ratchet has no power gain, either.

Buy by your standards, anything can have any amount of power gain, depending on how strange a mechanism it eventually starts up. An opamp can have a power gain of 1e20, if its output eventually opens a dam.

John