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    lighting circuit modification

    Hello, it's been a long time since my last post and i'm here again seeking advice from more experienced guys

    I have a night light that had it's incandescent 10W bulb die recently, and i've bought a 2.3W LED to replace it, but i've immediately noticed that when it should turn on, instead it's flickering. There was only ~130ish Volt AC across the leads for the bulb so i've thought that this must be some sort of dimming mechanism for the incandescent bulb. I've since taken it apart and drawn a schematics to the best of my ability.

    No here is the question. What would be the easiest thing to change in the circuit, to maintain the night/light sensing and be able to run the LED off it properly?

    Here's the schematic:


    Thanks in advance for any input

    #2
    Re: lighting circuit modification

    you need a resistor in parallel with the led lamp.
    i dont know what value, but that circuit uses the lamp as a source of power to the light sensor.
    led lights are not resistive, they are inductive.

    Comment


      #3
      Re: lighting circuit modification

      Originally posted by stj View Post
      you need a resistor in parallel with the led lamp.
      i dont know what value, but that circuit uses the lamp as a source of power to the light sensor.
      led lights are not resistive, they are inductive.
      Ok thanks, i can measure the resistance across LED's circuit, would that help in determining the required resistance?

      Comment


        #4
        Re: lighting circuit modification

        MCR100 is an SCR, so when it is turned on it outputs only 1/2 wave pulsing DC to the light bulb.
        Your LED lamp probably does not like this and may not work if it uses a capacitive dropper- then it really wants AC, not pulsing DC coming in.
        If you post a pic of the LED lamp's circuit, you can figure it out if it will work.

        Comment


          #5
          Re: lighting circuit modification

          Ok i'll check if i can take it apart without breaking it.
          Just a thought would it be possibile to change the MCR100 out for another element (if it exists), that would output entire sine wave to the lamp.

          Edit: I have been able to remove the plastic cover over the LED's, but the circuitry is inside the bulb's base and is not accessible unless i destroy the base :/
          Last edited by maxslo; 07-28-2019, 02:13 PM.

          Comment


            #6
            Re: lighting circuit modification

            I did find the same night light circuit but using a CR02AM-8A triac which should give full-wave to the lamp. It is hard to find very sensitive gate (100uA) thyristors.
            Attached Files

            Comment


              #7
              Re: lighting circuit modification

              Duplicate the circuit in reverse ...

              Comment


                #8
                Re: lighting circuit modification

                Thanks, this might be just what i was looking for, i'm just a bit confused about the information i read from the spec sheeet.

                namely this:


                why does it say half sine wave?
                Attached Files

                Comment


                  #9
                  Re: lighting circuit modification

                  The I2t (amp squared seconds) value is based on the time for a fuse blowing 10-16msec, or 1/2 cycle.

                  Comment


                    #10
                    Re: lighting circuit modification

                    i might add a capacitor if led flickers too much

                    Comment


                      #11
                      Re: lighting circuit modification

                      Ok thanks, i've ordered the relay. I'll update the thread once i install it

                      Comment


                        #12
                        Re: lighting circuit modification

                        Relay? The schematic on your post 1 using the SCR which means the 10W lamp is only be using 5W of power due to half wave action of the SCR, so when you use your meter the Voltage you test is the pulsing DC so it will not show 230VAC.
                        Never stop learning
                        Basic LCD TV and Monitor troubleshooting guides.
                        http://www.badcaps.net/forum/showthr...956#post305956

                        Voltage Regulator (LDO) testing:
                        http://www.badcaps.net/forum/showthr...999#post300999

                        Inverter testing using old CFL:
                        http://www.badcaps.net/forum/showthr...er+testing+cfl

                        Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                        http://s807.photobucket.com/user/budm/library/

                        TV Factory reset codes listing:
                        http://www.badcaps.net/forum/showthread.php?t=24809

                        Comment


                          #13
                          Re: lighting circuit modification

                          Half wave recitification.
                          https://www.physics-and-radio-electr...rectifier.html
                          Never stop learning
                          Basic LCD TV and Monitor troubleshooting guides.
                          http://www.badcaps.net/forum/showthr...956#post305956

                          Voltage Regulator (LDO) testing:
                          http://www.badcaps.net/forum/showthr...999#post300999

                          Inverter testing using old CFL:
                          http://www.badcaps.net/forum/showthr...er+testing+cfl

                          Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                          http://s807.photobucket.com/user/budm/library/

                          TV Factory reset codes listing:
                          http://www.badcaps.net/forum/showthread.php?t=24809

                          Comment


                            #14
                            Re: lighting circuit modification

                            Your project remind me a electronic project I have tried before about Electric Car Lamp, it's here: https://3celectrons.com/2019/07/25/d...-power-supply/

                            Comment


                              #15
                              Re: lighting circuit modification

                              This is a night light- how does it remind you of a bicycle light? Nothing in common unless you are trying to sell something.

                              Comment


                                #16
                                Re: lighting circuit modification

                                Originally posted by maxslo View Post
                                Ok thanks, i've ordered the relay. I'll update the thread once i install it
                                Sorry my bad, I meant the triac.. I've just seen that it was rejected to ship out of china due to security issue??? never had that happen before, so i've just ordered one from UK to avoid extra 1-2 months of wait time
                                I'll post back with results when i receive and intall it.

                                Comment


                                  #17
                                  Re: lighting circuit modification

                                  The triac arrived an i've installed it. The light now doesn't flicker anymore, however the light also doesn't turn off when it's daytime xD.. i'll give it another go tomorrow

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