Reading a Datasheet

Discussion in 'General Electronics Chat' started by bwilliams60, Mar 12, 2015.

  1. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
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    Attached you will find a datasheet for a U211B Phase Control IC. When reading these sheets, how do you know whether you are looking for AC voltage or DC voltage? Will it state it specifically or are you just supposed to know?
     
  2. crutschow

    Expert

    Mar 14, 2008
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    Generally the voltages are DC unless otherwise stated.
     
  3. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
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    So if I read this datasheet correctly, when referencing pin 2 (negative lead of DCV), I should get a minimum of 13.0VDC when I touch pin 3 with the red lead, correct?
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Fig3 shows a DC supply attached?
    +ve on pin 2 common on pin 3.
    Max.
     
  5. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
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    Did I read this wrong?
    "If the supply cannot be taken directly from the mains because the power dissipation in R1 would be too large, the circuit as shown in Figure 3-1 should be used."
    I do not see any rectifier anywhere on this unit. It has a single diode in series with a 6.5 K ohm resistor to the motor to pin 3. Also has the negative lead of 22uF and 2.2uF cap attached to it.
     
  6. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    That chip uses a Live Transformerless supply, as its used to phase control motors or heaters.
     
  7. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
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    Okay so what voltage should I expect to find at pins 2 and 3? AC/DC? I am fairly new to this type of adventure but trying to figure my way through this.
     
  8. Dodgydave

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    Jun 22, 2012
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    positive pin 2, negative pin 3,

    pin 2 is the ground,so pin 3 reads negative.
     
  9. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
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    Not sure what you mean. On one line you say positive pin 2, next line pin 2 is ground. Do I put my common lead on 2 or three. What should the voltage be when I do this?
     
  10. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    If you look at the datasheet, pin 2 is the ground pin so all readings are respectively from this, as its supplied on pin 3 from a half wave diode Negative, then all voltages on the pins will be Negative.
     
  11. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
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    Okay I'm good with that. I am assuming these will be DC and according to the datasheet, somewhere in the area of 13.0 V minimum? When I tested it, I found around -16.0 V average so that part must be okay. Now to figure out my next step.
     
  12. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    My...I like your determination.
     
  13. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
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    You don't learn if you don't DO! I'm bound and bent on getting this thing working. I just want to learn from it and move on but obviously I am out of my league on this one. But I will learn from it.
     
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  14. Dodgydave

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    Jun 22, 2012
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    Tell us what your trying to achieve,and then we can help you with it.
     
  15. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
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    I have been trying to tell you guys for two months on another thread. People jump in, throw 2 cents in and leave. I need someone to stay with me to figure it out. Not trying to sound like a whiner but I need help. I really appreciate every answer I get here but I'm still not at the finish line.
    In my thread "Need help with Phase Control and Triac, I have posted everything I can tell you about this problem but here is the summary.
    Woodworking Router with speed control using U211B and BTA24-600BW Triac - not working with SC - works when bypassed
    Replaced TRIAC, 1.5 pF capacitor, 22k ohm resistor, 380 k ohm resistor-No change
    Replaced U211B
    Unit now starts up, runs five seconds, shuts off (soft start begin??)
    Replaced TRIAC with another new one - same thing
    Replaced IC with another new one - same thing
    Posted all voltages found while in operation.
    End of story - starts/stops/starts/stops ....

    Thank you Dodgy Dave for your input
     
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  16. Dodgydave

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    Jun 22, 2012
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  17. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
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    To be honest with you I'm not sure. I have made a hand drawn schematic of my actual board but the values seem to differ from that of the datasheet and I cannot find anything that resembles a wire coming from the motor to indicate speed control. Here is my diagram.
     
  18. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
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  19. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    bwilliams60 check your thread please.

    Wait a minute...1.5pf replaced ?????
    Where ?
     
  20. Dodgydave

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    Jun 22, 2012
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    Think your diagram is wrong, check the circuit on page 23 datasheet onwards , and compare it with yours.
     
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