Automatic night light (outdoor)

Discussion in 'General Electronics Chat' started by amgkyocera, Aug 28, 2015.

please what can i do to prevent the heat and actuate the relay?

  1. do i have to change the 5w 68k resistor!! but this is the highest value that i can get in my country

    0 vote(s)
  2. or is there another type of dropper, can i use! or cooling system!

    0 vote(s)
Multiple votes are allowed.
Thread Status:
Not open for further replies.
  1. amgkyocera

    Thread Starter New Member

    Aug 28, 2015
    1- my 5watt 68k resistor heats too much! i have tried to lower the heat by putting 3 of the 5w 68k in series, that was ok!
    however when i connect the load the output voltage dropped!! please what what can i do to settle it?

    2-HYSTERISIS, the system is not able to actuate the relay

  2. dl324

    Distinguished Member

    Mar 30, 2015
    What is the AC input voltage? What wattage is the zener?
  3. amgkyocera

    Thread Starter New Member

    Aug 28, 2015
    thanks, I am using a 1 watt zener diode and the AC voltage is 230v 50hz
  4. #12


    Nov 30, 2010
    1) Your second transistor is drawn upside down.
    1a) There is no relay in that circuit. It has an opto-isolator.
    2) The main impedance to the current is the 225 capacitor. That means 722 ohms in series with 324 volts DC for a capability of passing .4488 amps into C2
    3) the 68K resistor can allow .00327 amps and should show 0.73 watts of heating. A 5 watt resistor should not be in danger under those conditions. The 68K resistor is not at fault. Something else is wrong.
    4) Using a 225 capacitor to limit the current to 137 times the amount of current allowed by the 68K resistor does not make sense to me. Besides that R4 is using up 0.0091 amps out of the available 0.00327 amps coming through the 68K resistor.
    5) Trying to fire a MOC3021 with 0.00236 amps is too low. The BT136 needs 0.011 amps minimum to fire in quadrant three.

    Summary: The number of illogical calculations shows that there is too much bad information for me to diagnose this circuit.

    Anyone care to check my math to see if I missed something?
  5. ScottWang


    Aug 23, 2012
    Welcome to the AAC forum.

    The owners of All About Circuits has elected not to host discussions of transformerless threads.

    This thread is against the AAC forum rules, Terms of Service (ToS).

    Any kind of over-unity devices and systems
    Devices designed to electrocute or shock another person
    LEDs to mains
    Phone jammers
    Rail guns and high-energy projectile devices
    Transformer-less power supplies
    Terms of Service (ToS).

    Transformerless power supplies of any kind are strictly forbidden. Therefore, this thread will be closed.

    Please try to understand the reasons behind this action, and feel free to browse and use the forums.

    You might find answers to your questions in one of these forums:

    Another good forum that shares many of the same membership is .

    Good luck.
Thread Status:
Not open for further replies.