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Discussion in 'Electronic Design' started by [email protected], Nov 13, 2008.

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  1. Guest

    I was arguing at work yesterday that relays have gain. Just because
    it's non-linear and electromechanical doesn't mean it has no gain. I
    mean a light switch has gain if you look at the power you can control
    with a finger. I think that silicon guys think gain must be linear or
    continuous, and be electrical in,electrical out. I think "gain" is
    much broader.

    Am I right? Who owes who a beer? And on that note, could a carbon
    particle microphone be so constructed that instead of a sound wave
    input, I put a small headphone-style coil on one side and then arrange
    it to have gain? Does a coherer have "gain"???

    Ah, the basics.
  2. Guest

    Oh, the central point of my argument is that nothing really has power
    gain, it's just that you can control a power supply with a device. And
    since a relay switches a power supply, it has gain.
  3. Eeyore

    Eeyore Guest

    Very unlikey that would have gain as such. Might just do if you had a piezo
    sound source.

    Mind you old simple telphone circuits worked OK but was it 'gain' ?

    Sounds fair to me.

  4. James Arthur

    James Arthur Guest

    100mW into a relay can switch 1kW or so, so that's a gain of
    10,000, minimum.

    James Arthur
  5. _

    _ Guest

  6. Guest

    Yeah, I remember that, I also recall some clever system to do with
    "police boxes", and I don't mean a TARDIS.
    Or was it a fire box? Oh well.
  7. James Arthur

    James Arthur Guest

    I was gonna say "whining"--baby bird chirps, momma bird
    barfs some food down its beak. Huge, but that's a
    different kind of 'gain.'

    James Arthur
  8. Guest

    Attach lever to ox. Whip ox. Ta dah! Power gain... :)
    /No actual oxen were whipped during this post
  9. Guest

    Very insightful, thanks.
  10. Guest

    Well I made a beer gain with my argument. Best kind, really. And I can
    make myself oscillate with beer. Vacillate, really.
  11. Rich Grise

    Rich Grise Guest

    A comparator _wants to_ have infinite gain. ;-)

  12. Guest

    Oh what about mechanical. The old fulcrum and lever.

    George Herold
  13. Guest

    opps good point!
  14. krw

    krw Guest

    Again, no gain. Does a transformer have gain?
  15. Rich Grise

    Rich Grise Guest

    No. It's an impedance transformer, but it has no power gain.

    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. :)

    (force<=>voltage, distance<=>current.)

  16. Rich Grise

    Rich Grise Guest

    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!
  17. Fred_Bartoli

    Fred_Bartoli Guest

    Nope. One gain nothing doing that.
  18. James Arthur

    James Arthur Guest

    Me too. If (electrical energy out / acoustical energy in) >= 1, that's

    James Arthur
  19. krw

    krw Guest

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

    Jasen Betts Guest

    12V 180mA relay coil switching 240V 10A

    10x voltage gain, 22x current gain.
    an a schmitt trigger-like transfer function.

    with a little negative feedback you could have a class-d amplifier
    with very poor bandwidth
    absolutely, Ive run old telephone mics and speakers off 12v and got sufficient
    gain for feedback-driven oscillations

    wikipedia furnished this link:
    probably, magnetic amplifiers, and spark gaps, do too.

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