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Thread: Connecting 2 circuits to one relay?

  1. #11
    Maximum Bitrate KyleYankan's Avatar
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    Wait ... 10 amps at 125vdc.... that's 1250 watts? More than enough? I posted about this earlier and was told it wouldn't do, but now I think it may. Can anyone confirm this. Thanks!

  2. #12
    MySQL Error Scouse Monkey's Avatar
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    yeah DPDT - that is what i meant. couldnt remember the name - silly me. Samw with switches etc if you want them to do several things.

    EDIT, but then relays are switches.

  3. #13
    MySQL Error Scouse Monkey's Avatar
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    Quote Originally Posted by KyleYankan
    Wait ... 10 amps at 125vdc.... that's 1250 watts? More than enough? I posted about this earlier and was told it wouldn't do, but now I think it may. Can anyone confirm this. Thanks!
    are you using it to switch the power to the relay?

    in that case you need 400W/12V = 33A

  4. #14
    Maximum Bitrate mushin's Avatar
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    Quote Originally Posted by Scouse Monkey
    are you using it to switch the power to the relay?

    in that case you need 400W/12V = 33A
    You mean to the inverter? And you have to factor in inverter inefficiency for draw, so it's more like 450W/12V = 37.5A (and that's 90% efficiency, which is probably optimistic). Of course if you don't need peak power, you can use a lower rated relay/switch, just make sure to fuse it <= to the rating.

  5. #15
    What can I say? I like serial. Curiosity's Avatar
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    I don't think you need 2 sets of contacts, but 2 inputs. Is that right? Example:
    How to build a very simple delayed power oft circuit?
    Large relay on the left, small one on the right (power button). None of the doides are zener, just standard and the 12V from the PC would be from the yellow wire of a molex (no need for a transistor).

  6. #16
    Maximum Bitrate KyleYankan's Avatar
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    Er... this thread kind of deviated from what I was asking. Let me rephrase for those of you who may be confused:

    I have two relays doing the exact same thing - only hooked to two different "triggers". Is there any way to consolidate this into one relay which both "triggers" hook into?

    Curiosity posted exactly what I needed. Just put two diodes on neach of those "trigger" wires, to prevent the current from one from pushing into the other. Thanks!

  7. #17
    Maximum Bitrate KyleYankan's Avatar
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    Err... one last question about the power capabilities of a relay. I have these relays here I would love to use - perfect for my application. They are DPDT. They say this "10A 24VDC" I guesstimate this to 240 watts. Now If I link both poles, would that double? to 480 watts? Diagram:
    NO pins : - -
    input: - -
    NC pins : - -

    hook them up like so
    NO pins : --
    input: --
    NC pins : --
    ?

  8. #18
    Stank Cheese n8scstm's Avatar
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    Im not sure but I think it would require 24 volts to throw the gate. I accidently bought a 120 volt relay once and it wouldnt open with 12 volts. I think what you trying to do can be accomplished with a diode but its just easier to use a dpdt. You can give these a try. http://www.partsexpress.com/pe/pshow...number=330-076 Its a socket that has the relay already in it. Then you can just use a standard spdt relay. Ive never used these so I'm not sure where the diode is but I think it's for your purpose.
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  9. #19
    Maximum Bitrate KyleYankan's Avatar
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    n8scstm - A SPDT works fine for what I need. However I want to be able to trigger the relay from two different circuits. I see no advantage of a DPDT. Still two tabs connecting the coil. What I wanted was to point out, cause I guess it's still confusing. I have 3 wires (2 Vcc 1 common ground) that I want to connect to a relay. I want either of the Vcc's to throw the relay, without damaging anything on the other Vcc. I was thinking diodes but never used them before, so I thought I'd post here. Curius answered my question with one of the schematics he sent me. Does anyone know of the other question?

    The relays work off of a 9v battry, so 24vdc @10a is defintly not the coil's rating. Does 24vdc @ 10a mean 12vdc @ 20a?

  10. #20
    FLAC shakes's Avatar
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    so then you want a SPDT (which we've determined) ... however, originally I wasn't clear on if you wanted two triggers for a single source or two triggers for two separate sources. That's why I said a DPDT ... If you want a DPDT to act like a SPDT (Single source) you can do so easily by connecting the proper pins on the bottom. Also, you'll increase the relay's current rating doing that.

    The relay voltage and coil voltage could be the same or different. usually on the casing it will list both voltages. if not it should be assumed they are the same.
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