MOC 3010, is it supposed to stay on ?

Discussion in 'General Electronics Chat' started by CVMichael, Oct 24, 2008.

  1. CVMichael

    Thread Starter Senior Member

    Aug 3, 2007
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    Hi,

    I want to turn on / off a light bulb (or whatever else) using a microcontroller, I used MOC 3010 to separate & protect the microcontroller, but the problem is that once the microcontroller turns it on, it does not turn off anymore.

    It's the first time I use MOC 3010, and I don't know what else I can use...
     
  2. hgmjr

    Moderator

    Jan 28, 2005
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    Can you provide a schematic of your design?

    hgmjr
     
  3. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    MOC3010 is designed to work in AC circuits. It won't turn off until the current through it goes to zero.
     
  4. CVMichael

    Thread Starter Senior Member

    Aug 3, 2007
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    I was suspecting something like that... (I am using DC)

    So what can I use instead of that for DC current ?
     
  5. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    You need an optocoupler. What are you trying to protect the microcontroller from?
     
  6. karthik_dm

    Member

    Oct 16, 2008
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    try this schematic which uses MOC3041
     
  7. Ron H

    AAC Fanatic!

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    Nice, but our OP said:
     
  8. beenthere

    Retired Moderator

    Apr 20, 2004
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    If the load current isn't above about 250 milliamps, he might be able to use a logic level FET like a VN10LP.
     
  9. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    I agree. There are also logic level MOSFETs that can handle a lot more current. He mentioned protecting the microcontroller, but has not come back to tell us what he needs to protect it from.
     
  10. CVMichael

    Thread Starter Senior Member

    Aug 3, 2007
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    Well, "protect" was a general word as in "just in case"...

    I want to do several things, to turn on/off other parts (Lights, LEDs, motors, etc. all DC current), and also to regulate power (as in a DAC).

    Before I asked this question: DAC with PIC16F877, but the only problem with that is that the ouput is 0 to ~4 volts.

    I was thinking to do something like this:
    [​IMG]

    Looking on google I found this, and I think it's what I need:
    TLP521 − 1,TLP521 − 2,TLP521 − 4
     
  11. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    I don't think you can use one solution to solve all the problems you mentioned. If all you want is a digital output, here are a couple of basic methods. There are many variations, depending on what you want to do. These are just ideas, and resistor values may need to be changed to meet the requirements of the parts you use.
    Connecting PIC ground to your output common (ground) defeats the purpose of an optocoupler, which is to isolate two power systems from each other. If you want to use common grounds, you don't need an optocoupler. A bipolar transistor or logic level MOSFET will do the trick.
    When you want to post a schematic or other line drawing, save it first as a .PNG or .GIF instead of .JPG. The drawing will come out crisper, without the fuzzy artifacts of a .JPG, and it will also generally result in a smaller file.
     
  12. karthik_dm

    Member

    Oct 16, 2008
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    for driving DC loads using microcontroller with electrical isolation, use an optocoupler like MCT2E,PC817,PC621 or any opto-transistor isolator package.at the output use a small DC Relay or a Transistor driver for driving the load.
     
  13. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    Agreed, except input and output grounds should not be connected.
     
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