12vdc electronic transformers

Discussion in 'General Electronics Chat' started by tried, Apr 10, 2016.

  1. tried

    Thread Starter New Member

    Mar 27, 2013
    11
    0
    I have electronic transformers rated at 12vac running my kitchen lights they are 12v 50w halogen down lighters. I recently purchased a 6 watt 12v LED marke3d as AC/DC lamp to use in these fittings. Bench testing this LED lamp it works perfectly on 12v either AC or DC. However it does not work on the electronic transformer. I have measured the output of the transformer with the 50watt halogen lamp connected and my digital meter reads 56vac Can anyone lead me to understanding why? Thanks in advance
     
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,791
    1,103
    Your meter is probably calibrated to read RMS volts when fed a nice sine wave. The 'electronic transformer' is probably kicking out anything but a nice tidy sine wave, so the meter doesn't read correctly.
     
    tried likes this.
  3. tried

    Thread Starter New Member

    Mar 27, 2013
    11
    0
    Ahh! I did wonder about that,do you think the ac bit inside the 12v ac/dc LED does not like the electronic transformer either ? . Those LEDs must have a circuit. in them to convert the 12vac to 12vdc?
     
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    The 12v AC/DC LED lamps I have seen all have a simple bridge rectfier to convert AC to DC
     
  5. tried

    Thread Starter New Member

    Mar 27, 2013
    11
    0
    Ahh! I did wonder about that!! Do you think the 12v ac/dc LED does not like the output of the electronic transformer either? I guess there is a circuit inside them as well to convert the ac to dc?
     
  6. tried

    Thread Starter New Member

    Mar 27, 2013
    11
    0
    That's magic ErnieM you answered the question just before I posted it !!!!
     
  7. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    Actually you asked it in post #3. I like to save my magic mojo for my own problems.
     
  8. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
    1,438
    368
    It's fairly well known that electronic transformers designed for halogen lamps don't usually work well with LED replacements; it usually results in unacceptable random flickering.

    I keep meaning to investigate the cause with the intention of adding "something" between the transformer and the LED to eliminate the problem, although it may not be possible.

    It appears that there may be a chip for this:

    https://www.maximintegrated.com/en/products/power/led-drivers/MAX16840.html
     
    Last edited: Apr 11, 2016
Loading...