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What is this symbol in this circuit and its functionality?

  1. May 15, 2015 #1
    I have been working on a circuit and the manual shows a diode in parallel with "CR". I think it might either a control relay or a crystal rectifier. I am having problem building the part between +ve terminal of the 24VDC power supply and the 9 /IN POSITION terminal Can anyone please help me figure out how to achieve this circuit? This is a part of a control panel for a torch lifter system. Any input would be appreciated.

  2. jcsd
  3. May 15, 2015 #2


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    CR is the coil for a control relay. The diode is there to protect associated circuits from flyback when the magnetic field in the relay coil falls.
  4. May 15, 2015 #3


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    yes agreed and the contacts for the said relay are the ones you see just above it, the single pole double throw
  5. Jul 10, 2015 #4
    I don't wanna make a new thread because this is a really dumb question, so I will use this one. I hope it's ok.
    So my question is: What kind of device is in red circle?
  6. Jul 10, 2015 #5
    It looks like a capacitor, but I don't know what that semicircle is at the end of it.
  7. Jul 10, 2015 #6
    I am pretty sure it is showing a cap with the other end of the cap terminating on the shield of the conductor - that is why on the end near the switch there is also the Ground symbol floating in "space" Indicating the shied is grounded at the controller end, and the far end ( termination) has a capacitor to the shield to pass any noise or V spikes to the shield.
  8. Jul 10, 2015 #7


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    I've never seen this way of expressing those standard symbols before. Interesting and makes sense. Is this a "standard" used in "data/com" or some other wiring specialty?
  9. Jul 11, 2015 #8
    Thanks for replies. I made some additional reasearch myself and it looks like it is voltage presence indicator based on capacitive divider, which actually makes sense, because I saw the symbol mainly in hight voltage schematics.
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