Transformer Help

Discussion in 'G / O / S Scale Model Trains' started by gkcooper365, Feb 6, 2008.

  1. gkcooper365

    gkcooper365 New Member Old S Scale

    I have an old American flyer 18B transformer. Both variable voltage circuits work fine, although at max throttle they read 19.2 volts on my meter..
    The fixed voltage is putting out 19.2 volts all the time instead of 15 as it should.
    Any ideas if this an be corrected? Are there any adjustments available? I have looked at the books I have and can not find any discussion about this.
    Thank you in advance,
  2. rogerw

    rogerw Active Member

    With no load on them that should be about right.
  3. gkcooper365

    gkcooper365 New Member Old S Scale

    Hi, thank you for the response, actually that reading is with 7 or 8 bulbs lit. I am concerned because the lights are very bright and get rather warm quickly. I am thinking the fixed voltage needs to be closer to 15 as advertised.
    Are you getting the same kind of readings on the fixed voltage terminals?
    Thank you,
  4. pgandw

    pgandw Active Member


    Another sneaky issue is that line voltage (voltage at the outlet) has risen nearly 10% over the years. Lionel and American Flyer built their transformers for 110-115 volts. Today, most utilities try to keep the voltage up around 120 volts - except during "brownouts" when it can be reduced as low as 100 volts or so. An extra 10 volts at the primary translates into 1 to 1.5 volts extra from the secondary.

    And some of the transformers ran high anyway. Lionel's KW is known for having a 20 volt fixed output if wired as expected - which overheats and shortens the life of bulbs in the 022 switches. On my particular KW, the 14 volt fixed is actually only putting out 11 volts - frustrating because I need the extra for the switch machines.

    Without rewinding the transformer, there is no way to adjust any of this.

    With variable circuits, you can set the voltage to where you want it and mark the dial. The fixed voltage circuits are a bigger concern.

    Light bulbs will last much longer if they are run about 10-20% under rated voltage. So if you are running the circuits at 19 volts, I would switch to 24 volt bulbs. Or reduce the variable voltage to 15 volts for 18 volt bulbs, and 14 volts for 16 volt bulbs.

    my thoughts, your choices
  5. gkcooper365

    gkcooper365 New Member Old S Scale

    Hi, thank you for your explanation. Imagine that, my house current is measuring 124 volts.
    The light bulbs on my switch contollers are almost blinding. Do you have a source for the 24 volt bulbs you mentioned?
    I have been looking at buying another transformer for accessories, hadn't thought about using the variable voltage circuit for them. Good idea.

    Thanks again,
  6. pgandw

    pgandw Active Member

    I haven't bought light bulbs in a few years. I would try the usual parts sources - Warren's, etc. Sorry, I'm not much help this time.

    If you have access to a different meter, you might want to compare. It's possible that your meter is reading a little high across the board - but not likely. And you still do have a for-real high voltage situation; it's a matter of how high.

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