Connect with us

False Trigerring

Discussion in 'General Electronics Discussion' started by [email protected], Jul 5, 2011.

Scroll to continue with content
  1. sanjay.b1976@yahoo.co.in

    [email protected]

    10
    0
    Jul 4, 2011
    I am using MM74hc123A for controlling 4 O/Ps, three of them are CFL and one is ceiling fan. To regulate the speed of fan, regulator is been used. But as I go to control the fan speed via regulator, the other O/Ps i.e. CFL also fluctuate( provided all of them are in off state) , means all the CFLs glows for fraction of second and then goes out. And this happens only when I try to control fan speed via regulator. Faster I rotate the regulator, the frequency of the CFL getting ON and OFF also increases.

    How can this problem be resolved, without changing the IC.

    P.S.-The IC is driving relay , which is further controlling O/Ps
     
  2. sanjay.b1976@yahoo.co.in

    [email protected]

    10
    0
    Jul 4, 2011
    Removal of CFLs is not helping
     
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,271
    2,718
    Jan 21, 2010
    A circuit diagram would be useful. It would answer questions like "what sort of regulator", "how are you using a CMOS device to a mains appliance", etc.
     
  4. sanjay.b1976@yahoo.co.in

    [email protected]

    10
    0
    Jul 4, 2011
    Regulator is being connected as external device and it is simple potentiometer type one. Fan consists of coils which act as energy storage and as we try to vary speed via regulator for fraction of second supply is cut off to the fan and as a result of it the field of the coil collapes and produces current in reverse direction----can this be one of the reasons.

    P.S.- Schematics are as attachment.
     

    Attached Files:

  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,271
    2,718
    Jan 21, 2010
    Are you playing games? You put a circuit diagram in a PDF, then take a screen capture of it, place it in a word document and zip it.

    Just attach the original image, or the pdf of it.

    By the time I've gone through that many layers of unzipping and opening, I've forgotten what I wanted to look at.

    I don't see a "simple potentiometer" regulator, but I do see you switching a series of relays from the output(s) of a CMOS device. You also appear to have a rather long period RC delay.

    Do the relays (operating from 12V) do what they're supposed to do?

    What rate are they switching on and off?
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,271
    2,718
    Jan 21, 2010
    I'm just guessing here, but is it a fan with an inbuilt lamp? And the lamp goes off when you play around with the power to the fan?

    Could it be that you are interrupting the power to the lamp as well?
     
  7. sanjay.b1976@yahoo.co.in

    [email protected]

    10
    0
    Jul 4, 2011
    Can't attach originals, as there is file limit.

    Regulator is connected externally on the switch board, so it is not the part of schematic.

    Relays are doing there part.

    O/P of CMOS device is switching Relays. and each relay is controlling one O/P, so there are total 4 O/P loads - 3 CFL and one fan.

    Evry thing works out as per design expect the fluctuation of CFLs
     
  8. sanjay.b1976@yahoo.co.in

    [email protected]

    10
    0
    Jul 4, 2011
    No, it is not a fan with inbuilt lamp

    Fan is one of the O/P device controlled by the board along with other three CFLs.

    All the O/P devices are controlled independently.


    One thing more, how can I control the reverse current generated by "back emf" of the coil of the fan from entering into I/P power supply.
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,271
    2,718
    Jan 21, 2010
    You're right. It's totally impossible.

    [​IMG]

    Oh well.

    Are the relays connected to the CFL lamps turning on and off too?
     

    Attached Files:

  10. sanjay.b1976@yahoo.co.in

    sanjay.b19[email protected]

    10
    0
    Jul 4, 2011
    Yes, relays are also turning on and off.
     
  11. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,271
    2,718
    Jan 21, 2010
    OK, so the relays to the CFL's are turning on and off and you are confused as to why the CFL's are not staying on?
     
  12. sanjay.b1976@yahoo.co.in

    [email protected]

    10
    0
    Jul 4, 2011

    Nops...........the situation is as follows:-

    1) The CFLs should remain in OFF condition as the respective switches of them are in OFF state.

    2) The only switch that is in ON state is that of fan.

    3) To control the fan speed , we have connected "step type fan regulator which is having 5 steps) in series to the fan supply.

    4) Now to vary the speed , we vary the fan regulator steps, as we do so , the CFLs also turns ON-OFF.

    5) So my confusion is that why CFLs turns ON-OFF as I try to vary fan speed, Why they don't remain in permanent OFF state.
     
  13. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,271
    2,718
    Jan 21, 2010
    OK, but in response to a previous question you told me that the relays controlling the CFLs are turning on and off.

    So are they? Or are they always off, and the CFL turns on anyway?

    I assume you mean relay, not switch? And therefore you confirm that the relay contacts for the CFLs remain open.

    I'm not familiar with "step type fan regulators". Is this a separate controller you switch to the correct speed?

    So as you manually do stuff with your "step type fan regulator", nothing at all happens in the circuits you've shown me (i.e. no change in relay states, or anything else) but the lamps go on and off?

    Well, as I see it, we still don't have enough circuit diagram to show how the CFLs and the fan are connected, so I will simply assume that the CFLs are connected via your relay contacts in parallel with the fan and its controller.

    Do the lamps emit a brief weak flash, or do they fully turn on. If the latter, for how long?

    It's not unusual to see a CFL bulb emit a brief weak flash as you connect or disconnect it from an otherwise dead circuit. I presume this is due to capacitive effects. It is possible that switching the fan causes sufficient inductive effects to tickle the bulbs into emitting a weak flash.

    If you tell me that the lamps come on full brightness (or significantly bright) and that the relay contacts are open, then I will be somewhat amazed. It could be that you have a live/neutral fault and that you are seeing some sort of capacitive coupling through to earth, but... well, let's hear what you say.
     
  14. TBennettcc

    TBennettcc

    292
    2
    Dec 4, 2010
    Sanjay,

    How big are the PDFs of your circuit diagrams? 1MB? 5MB?

    Also, just because something isn't "on the physical circuit board," it is still very much a part of the circuit. Please include EVERYTHING in your circuit with AS MUCH DETAIL AS YOU CAN. Please make sure that EVERY PART in your schematic diagram is LABELED with a LETTER and a NUMBER at the VERY LEAST (e.g., R5 for resistor 5, Q1 for transistor 1, etc.) This helps us to discuss the circuit with you, and communicate effectively, instead of having to say "the second resistor to the top-left of the first inductor... etc.", we can just say R5. Done. Simple.

    The more information we have, the better we can help you.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-