AC SSR Project

Discussion in 'The Projects Forum' started by ShakeECET109, Mar 28, 2011.

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  1. ShakeECET109

    Thread Starter Member

    Apr 10, 2008
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    Hi Guys,

    I am working on a project creating an SSR, DC input and AC output.
    Input control voltage is 3-30VDC and the relay has to be able to drive a 50-120VAC load having a min current rating of 1 amp. The input and output have to be optically isolated.

    The challenge is that I have to design this SSR only using transistors,diodes and opto-isolators and I cant use any electromagnetic relays or any moving parts.

    I am wondering if there are any DIY projects I can follow and use as guidelines. Is this a simple project to make? Will I need to mount the components on a PCB board or can I use a small bread board? Anyone have any idea on how many components I might need?
     
  2. ShakeECET109

    Thread Starter Member

    Apr 10, 2008
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    [​IMG]


    Is this a schematic I can follow?? The MOC3021 is suitable for 120VAC correct? How can I tell if this circuit will drive a 50-120VAC with Input control voltage is 3-30VDC?
     
  3. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
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    This is obviously a school assignment so the kind of help we'll give will not be direct. You can google those component models and easily pull up the data sheets for them.
     
  4. ShakeECET109

    Thread Starter Member

    Apr 10, 2008
    19
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    I choose to go with a different design.
    [​IMG]

    I bought my parts, but I need a 50VAC-115VAC load and I do not know what to use?

    Same goes for the 5 VDC input, I was just going to use 9v battery with a voltage regulator. Could I also use a 4 AA NiMH batteries? How would i connect them to the solder less bread board??

    I have to enclose the whole circuit so any tips on how to do that would be appreciated. Thanks
     
  5. CDRIVE

    Senior Member

    Jul 1, 2008
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    How about a table lamp.
    With battery holders.

    I'm not a safety freak but I certainly hope that you're not connecting your mains to a solderless (protoboard) breadboard. If you are it's exceedingly dangerous!
     
  6. ShakeECET109

    Thread Starter Member

    Apr 10, 2008
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    Thanks for the info.

    Is there a better way to set up the circuit instead of using the solder less bread board?

    The load has to be 50VAC to 115VAC with a min current rating of 1 amp. Are there any small motor I can use as the load that fits the criteria??
     
  7. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    A 100W/115VAC light bulb will be ~1A load. The bulb is the load. "50VAC to 115VAC" is the voltage supplied "to" the load. The only way you can simulate that voltage range is with a variable autotransformer. Ask you instructor for access to one.

    Ken
     
  8. Adjuster

    Well-Known Member

    Dec 26, 2010
    2,147
    300
    This is really not a good idea for solder-less breadboard construction. You can't have wires falling out of little clips at any moment in a power circuit, and I doubt whether the voltage and current ratings would be up to it anyway. A soldered construction is required, with proper support and heatsinking for the triac.
     
  9. ShakeECET109

    Thread Starter Member

    Apr 10, 2008
    19
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    Our instructor does not want us to demonstrate the full range he just wants the load to be within the given range so the light bulb should be sufficient.

    I am going to use the 4 AA battery holder for the input. I think that is a total of 4.8 volts will that work since my design needs 5 volts dc input?

    I do not have the time or else I would use cadence and have the design printed on a PCB board. is there another way to work around this???
     
  10. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
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    First off please read my disclaimer that's at the bottom of my posts. Assisting in mains related projects always makes me uneasy. Use extreme caution in all your handling of the mains.

    Please post the part number of the Triac that you're using so we can recommend a PCB.

    Your 4 AA cells should work fine. Recalculate value of R1 for 6V. BTW, how did 4 AA cells add up to 4.8V? Are they Nicads?

    Breadboarding recommendations:

    You can use your solderless protoboard for the breadboard phase but not using the mains. Hookup to the mains should be reserved for the finished model only. To test your circuit on the protoboard use a 24V-48V transformer in place of the mains supply and a scale the load for testing.

    Finished model:
    When you're satisfied that all is working well you can build the finished model into a UL rated (deep) duplex or double duplex handy box. These are surface mount AC wall outlet and switch boxes that you typically see in industrial environments like work shops with concrete walls. The 1/2" knockouts on the box will accept a Romex type cable clamp for your 120VAC power cord.

    Some universal project boards...
    For your project I like this one best but I'll probably recommend some mods to it for safety sake.
    http://www.radioshack.com/product/index.jsp?productId=2103799

    Here's another.
    http://www.radioshack.com/product/index.jsp?productId=2102845
     
  11. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Plenty of isolated opto-triac drivers available, shouldn't be that hard to look up the data sheet on some and one is bound to have example circuits.
     
  12. ShakeECET109

    Thread Starter Member

    Apr 10, 2008
    19
    0
    regular old alkaline batteries have a nominal rated voltage of 1.5v
    4 alkaline X 1.5v = 6v

    NiMH rechargeable batteries, on the other hand, have a nominal rated voltage of 1.2v. The receiver pack uses four "AA" cells. Or...

    4 NiMH X 1.2v = 4.8v

    ----

    This is the triac I am planning on using
    4 amp triacs
    http://www.goldmine-elec-products.com/prodinfo.asp?number=G15230&variation=

    Lert me know if anyone has better suggestions for the triac.


    Should I even use a Romex type 120VAC power cord. like shown in the design?? Is this something typical for SSR's? Most SSR's I have looked at just had the screw terminals. Which would be easier? more efficient ?


    Thanks for all the help guys
     
  13. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
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    I didn't suggest using Romex. I said the cables clamps for the 1/2" knock out was made for Romex. They will accepts a round neoprene 3 conductor power cord too.

    Yes, I realize that nicads and NiMHs are lower in voltage. That's why I asked.
     
  14. ShakeECET109

    Thread Starter Member

    Apr 10, 2008
    19
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    so far i am planning on using a small 115Vac lamp for my load. I am trying to figure out how I can plug the power cord from the lamp "into" my circuit. I am definitely going to use the universal prototype board you have recommended .
    I have no experience with them though, how easy are they to use?
     
  15. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
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    I'm a bit confused? I thought you wanted to build your own SSR, like The discrete circuit that you posted. If you simply want to purchase a SSR module then yes, they will typically come with four screw terminals, +- input and AC (closure) output.
     
  16. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    If you use a SSR module there will be no need for a breadboard or project board at all.
     
  17. ShakeECET109

    Thread Starter Member

    Apr 10, 2008
    19
    0
    Yeah, sorry for the confusion. I want to actually build my own SSR, but I was thinking I needed to build it to look exactly like a store bought opto isolator-triac SSR.

    I was wondering if I should build the SSR with 4 screw terminals and use the 4 battery s for the DC input and somehow connect a lamp to the over screw terminals.

    We went of the design and function of SSR's in class, but we never went into detail on the fabrication. He did not set any rules that it had to have 4 screw terminals I was just wondering if it would be easier.
     
  18. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    I was describing this arrangement but with an appropriate length cord. That's a surface mount duplex handy box in the video. They make them in 2 gang, which will give you more room inside the box. They also make them in a few depths. They're sold at home depot and hardware stores.
    http://www.youtube.com/watch?v=WzLkj0TCNHM

    BTW, the more I read in this thread, the more I question why your instructor gave you a dangerous 120VAC project. If you've never used a universal project board before, I seriously question his judgment. For that matter I'm seriously questioning my judgment for for the same reason!

    Moderator input please!
     
  19. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    RE SSR:
    The lamp doesn't get connected across the two AC terminals, it gets connected in series with one of them. Following electrical standards one AC terminal should be connected to AC "Hot" (black). One leg of lamp (black) gets connected to the other AC terminal and the other leg of the lamp (white) gets connected to AC "Neutral".
     
  20. ShakeECET109

    Thread Starter Member

    Apr 10, 2008
    19
    0
    I think thats why the instructor set the range of 50-120VAC Load having a minimum current rating of 1 amp. A couple other guys in my class were using a pretty large 2 amp motor as there load.

    I have taken a class with the same teacher where we used Allegro to design a circuit and Cadence Layout plus to create the Gerber files in order to have the designs printed on a PCB board. The difference there was that we were only using 9v battery's to power 2 -seven segment LED's.

    Not saying this is the safest project, but regardless I need to get it done. The help you guys are giving me is great and will obviously help me get it done safer then if I went at it by myself.
     
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