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Re: Electronic Terminology Was: Power question .........

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  • tmiktrain
    One of the unsolved point is HOW TO WAIT TWO MINUTES before turn on the first siren. ... from 10 ... I cannot beleave this is the only one solution for this
    Message 1 of 9 , Oct 4, 2002
      One of the unsolved point is HOW TO WAIT TWO MINUTES before turn on
      the first siren.
      > or HOW TO WAIT FIVE MINUTES before turn on the second one.
      >
      > Think that this two minutes and five minutes must be configurable
      from 10
      > seconds to 6 minutes. (aproximately)
      I cannot beleave this is the only one solution for this very simple
      time problem.

      Tony says

      You are right there is a much easier and cheaper way... use a 555
      timer these cost only a couple of $ and are very reliable and can be
      adjusted to suit almost any time delay, milliseconds to hours and
      operate on 5 - 16 volts DC and can sink or source up to 200
      milliamps which should be enough to drive your relay. The relay
      would nead to have a reversed biased diode across the coil to
      dissipate the back emf generated when the relay turns off. If you
      like I will draw a circuit for you and post it here. I would need to
      know the coil resitance of your relay this is measured in ohms


      Remember every siren alarm are 12 V DC and use 1.3 Ah, so we have
      2.3 Ah with 12 V DC.

      ***** Maths corection 1.3 + 1.3 =2.6 amps

      > The electronic shop give me one relay for the TWO sirens alarms
      with the
      > following characteristics:
      >
      > ************************
      > ISKRA
      > TRM 3013
      > _____
      > 12V - - - - -
      > _
      > _/ _
      > _ 10 A 250 ~
      > _/ _
      >
      > ************************
      >
      > Which means, if I understand correctly, the resistance to control
      the really
      > is 12 V DC
      > and this is a two ways relay for 220V AC and for 10A.
      >
      > BUT THE SIREN ALARM IS 12V DC and something tell me this relay is
      not the
      > correct one (I smell something wrong).
      >
      > If my alarm is 12V DC why I have one relay specification with 10A
      250V AC??

      Tony says

      The 10 A at 250 volts is a maximum rate and should be fine for your
      aplication but you would need 2 relays
      Hope this helps.
      Tony
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