Halogen lamp Transformer Issue

Discussion in 'General Electronics Chat' started by jsthomps, Jul 31, 2010.

  1. jsthomps

    Thread Starter Member

    Mar 30, 2010
    15
    0
    Hi all,
    I'm obviously missing something here. I purchased an EPROM programmer on eBay but it was missing the power supply. The missing wall wart generated 12VAC and can provide up to 3amps. Sounds simple ... I decided to buy a transformer used for low volt halogen lights (12VAC 5amps). Plugged it into the wall and measured the output ... 0VAC :confused:
    Returned it because I thought it was defective and bought a different transformer http://tinyurl.com/25clr7w
    Plugged it in ... 0VAC :confused:
    I soon realized that these units might be switching power supplies and that they might need a load. Loaded the output with the EPROM progammer and ... 0VAC :confused:
    All I want is a simple class 2 transformer that can provide 12VAC at 3amps.
    What am I missing here?
    Thanks,
    Scott
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Switchers will output DC, and so are not suitable. You must have a meter - what does it indicate the line voltage is? Just for a check of function - it's hard to imagine all those transformers with no output. Are you setting it to the AC ranges?
     
  3. jsthomps

    Thread Starter Member

    Mar 30, 2010
    15
    0
    Hi,
    I'm pretty handy when it comes to electricity and electronics. I have a nice auto-ranging DMM and I double checked that I had it on AC volts. Line voltage reads 120VAC, output volatge reads 0VAC. The transformer's says "for 12v halogen lights only" and "operating frequency > 20KHz". I thought that this would be a no-brainer but I'm very confused. Just to make sure I had not developed dementia, I powered up and measured a door chime transformer. All voltages a expected. Did you take a peek at the link I provided? Here is the other transformer I tried with the same result http://tinyurl.com/342az32
    Scott
     
    Last edited: Jul 31, 2010
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
  5. jsthomps

    Thread Starter Member

    Mar 30, 2010
    15
    0
    Yes you are right ... mystery solved. I throw it on my scope and it's switching at 160KHz :eek: You learn something new every day.
    Thanks for your help
    Scott
     
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