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Using a relay

Discussion in 'Electronic Basics' started by Jan Nielsen, Apr 24, 2007.

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  1. Jan Nielsen

    Jan Nielsen Guest

    I got a relay I cant figure out how to use, it as 5 connectors.

    Its a finder 5V(dc) 10A 250V(ac), I dont have a
    datasheet for it.

    The legs are like this
    O_O 1_2
    OOO 345

    1=NO (Normally open?)
    2=NC (Normally closed?)
    3=no label
    5=no label

    Anyone know how to use this, if its even something I can use :)

  2. It looks like the 5 volt DC coil is connected between pins 3
    and 5.

    When unpowered, there should be a (normally) closed contact
    between pins 4 and 2.

    When 5 volts is connected to the coil, there should be a
    contact closure between pins 4 and 1.

    Check the resistance between pins 3 and 5, to see if it is a
    reasonable resistance for a 5 volt coil. I would expect a
    resistance between 25 and 100 ohms.
  3. Doug Miller

    Doug Miller Guest

    What you have is a single pole double throw (SPDT) relay. The coil is rated
    for 5 VDC, and the contacts are rated for up to 10A at 250VAC.

    NO and NC are, as you surmised, normally open and normally closed. Pins 3 and
    5 would be the relay coil. Pin 4 (COM) is the common terminal, connected
    (internally) to pin 2 (NC) when the relay coil is not powered, and to pin 1
    (NO) when the coil is powered.

    - no current across pins 3 & 5: pin 4 is connected to pin 2, and not to pin 1
    - 5VDC across pins 3 & 5: pin 4 is connected to pin 1, and not to pin 2

    Whether this is something you can use, depends on what your application for it
    might be.
  4. Jan Nielsen

    Jan Nielsen Guest

    Doug Miller skrev:
    It works, thanks :)

    seems wierd to have the com so close to the 5vdc, since it can be
    dangerous voltage ?

  5. I agree. I would not use this relay to switch line voltage,
    unless the 5 volt supply was completely and safely isolated
    from any chance of being touched, and was referenced to the
    voltage applied to the common.
  6. Jan Nielsen

    Jan Nielsen Guest

    John Popelish skrev:
    Some time in the future I plan to switch line, but probaly with another
    relay, its a jungle :)

    I just need a Normally Open relay rated for a few amp 230V, and
    triggered by 5vdc so I can do it from a logic circuit.

    This one is rated for 24VDC too, so I will find some uses for it :)

    Is that a Single Pole Single Throw - Normally Open then ?

  7. Doug Miller

    Doug Miller Guest

    That's correct. Of course, a double-throw relay can be used in place of either
    a single-throw NO or a single-throw NC -- you just leave the other terminal
  8. Pete D

    Pete D Guest

    You cannot generally switch a relay from a logic circuit, logic circuit
    will not provide enough mA, you will need a transistor between the
    output and the relay
  9. Jan Nielsen

    Jan Nielsen Guest

    Pete D skrev:
    Ok, the pics I use can handle 20mA current draw on the out pins.
    Still waiting for a new fuse to be able to measure amp, oops :)

  10. Pete D

    Pete D Guest

    You have a point, I was thinking logic gates not MPU, just thought it
    worth mentioning, as the original poster didn't know how to wire a
    relay, i suspect not using a MPU.
    Of course I could be wrong, I usually am ;-)
  11. Jan Nielsen

    Jan Nielsen Guest

    Pete D skrev:
    I am the OP :)
    I started playing with electronics a few months ago, so even after a lot
    of reading, its still pretty basic.

    I am using the picaxe, not a "real" pic but a lot faster to code on
    (mostly because I dont know c, cpp or assembly).

    but yes its worth mentioning, I already killed one of their medium range
    chips, not sure how, but resistors and making sure not to draw much more
    than a relay, transistor or led from the pins could be a start :)

  12. Pete D

    Pete D Guest

    Oh mine is pretty basic, after a mere 30 years, sokeep plugging away at it
    If you want to program 'real' PIC's but want to stick to Basic, have a
    look at their Proton basic is very powerfull, there
    is a free sample version with a limited no of lines of code.
  13. Ross Herbert

    Ross Herbert Guest

    The Finder website isn't working so trying to get data is hopeless.
    Nevertheless, The Relays-R-Us website in the UK does have some info on
    the 36 series
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