IC relay?

Discussion in 'The Projects Forum' started by rubicon99, Apr 30, 2012.

  1. rubicon99

    Thread Starter Member

    Apr 19, 2012
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    Are there any IC chips that have relays in them? Rather not a solid state relay. I just want to amplify voltage with a switch on or off in an ic chip.
     
  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Google: DIP relay
    These are relays that are packaged in DIP packages like ICs, and can be pluged into DIP sockets.

    Ken
     
    Last edited by a moderator: Apr 30, 2012
  3. rubicon99

    Thread Starter Member

    Apr 19, 2012
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    Actually I guess solid state relays are fine
     
  4. KMoffett

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    Dec 19, 2007
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    What are you trying to do? Can you post a schematic?

    Ken
     
  5. mcgyvr

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    Oct 15, 2009
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    A transistor..
     
  6. rubicon99

    Thread Starter Member

    Apr 19, 2012
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    I found this... pretty much making an estop system with a microcontoller that will give a ttl signal and amplify it to 12-24 volts if I give a high, or give 0 volts if I give a logic low. I attached a schematic, but I need to change it and get rid of the ULN2003 cause since I am pulling high a load to ground will change the voltage.

    I found this... Can I use it, it says solidstate relay but its using mosfets to do switching. Do yall think it will work for my application?
    http://www.vishay.com/docs/83804/lh1500aa.pdf
     
  7. KMoffett

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    What's the current in the 12-24V e-stop circuit?

    Ken
     
  8. rubicon99

    Thread Starter Member

    Apr 19, 2012
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    max 200 MA... more like 100 MA
     
  9. KMoffett

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    That would be pushing that SSR, since it's only rated at 150mA.

    Ken
     
  10. rubicon99

    Thread Starter Member

    Apr 19, 2012
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    In that datasheet, would you input the ttl signal to the LED? Have ground on the S' pin and output on the S pin?
     
  11. SgtWookie

    Expert

    Jul 17, 2007
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    The solid state relay has an Rds(on) of 20 Ohms. That means when it is conducting, it's resistance will be 20 Ohms.

    For 200mA to be flowing from a 24v supply requires a 120 Ohm resistance. So, assuming your load is 120 Ohms, and the solid state relay has a resistance of 20 Ohms when it's on, your actual current will be about 171mA, and your load will have about 20.6v across it; 3.4v across the SS relay. You probably won't like that.

    It would have helped if you had mentioned your load current prior to now.

    More on SSR's; keep in mind that many of them use Triacs or SCRs internally, which will not turn off if you are using DC.
     
  12. KMoffett

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    Dec 19, 2007
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    Yes...but...the Ron is ~20Ω. At 200mA that's a voltahe drop of 4 volts across the "contacts" and a power dissipation of 800mW. The absolute maximum continuous Pdiss is 550mW.
    Ken
     
  13. rubicon99

    Thread Starter Member

    Apr 19, 2012
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    Damn a 4 volt, voltage drop. Are there any solid state relays where I won't have a voltage drop. I don't think there is a voltage drop in elctromagnetic relays.
     
  14. rubicon99

    Thread Starter Member

    Apr 19, 2012
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    So prob not a good idea to use a solid state relay for my application. Any suggestons where I can amplify voltage if I swithed the state on my microcontoller or turned it off.
     
  15. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Its VERY common in the micro world to simply use a digital output pin feeding a transistor..feeding a relay to switch high voltage/current loads..
    With this setup a 5V high or 0V low can be used to switch very large devices on and off from a micro output..

    Even just a transistor can be used for smaller (but more than the micro pin can supply) loads

    Just like this
    http://www.arduino.cc/playground/uploads/Main/relays.pdf
     
  16. rubicon99

    Thread Starter Member

    Apr 19, 2012
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  17. KMoffett

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    Your schematic doesn't show anything about the 12-24V circuit. Can you post that?

    Ken
     
  18. rubicon99

    Thread Starter Member

    Apr 19, 2012
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    Its the input voltage. Depending on the input voltage that is given. In the previous schematic you have a 12-24 volt input that I would feed into the ULN2003 and now I guess I would do that with the solid state relay. The output would just have a load from 1k - 10K.
     
  19. KMoffett

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    Looks like the same schematic. Are you saying that the 12-24V is Vcc on the schematic, and you need a high-side switch to turn that on and off with a logic output from the uC?

    Ken
     
  20. rubicon99

    Thread Starter Member

    Apr 19, 2012
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    Yes, the 12-124 is just VDD, the input voltage, Yes I just need a high side swtch. The reason why the schmatic doesn't work is if I attaced a load going to ground from the output (ULN 2003 output after the pull ups) it will act like a voltage divider and I need the output voltage to be as high as the input if it is turned on.
     
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