Using an AC-to-AC wall wart transformer/adapter in reverse

Discussion in 'Misc DIY' started by Matt, Feb 7, 2009.

  1. Matt

    Matt Guest

    Suppose I have a plug-in transformer that reduces 120VAC power to some
    lower AC voltage (say 12VAC or 24VAC), and suppose I want to do the
    reverse---increase a low-voltage source back up to 120VAC.

    Would there be a problem in connecting the low-voltage power to the
    plug-in prongs of the wall wart (instead of the normal use: plugging the
    prongs into the wall outlet) and expecting to get high-voltage power
    back out the other end?

    I guess my question is answered if I know that there are no components
    other than the transformer inside the wall wart.

    My immediate need is to use a 24VCT (center-tapped, 3-wire, 12VAC or
    24VAC) to convert 24VAC back up to 120VAC.
     
    Matt, Feb 7, 2009
    #1
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  2. Matt

    RBM Guest

    "Matt" <> wrote in message
    news:VJojl.475$...
    > Suppose I have a plug-in transformer that reduces 120VAC power to some
    > lower AC voltage (say 12VAC or 24VAC), and suppose I want to do the
    > reverse---increase a low-voltage source back up to 120VAC.
    >
    > Would there be a problem in connecting the low-voltage power to the
    > plug-in prongs of the wall wart (instead of the normal use: plugging the
    > prongs into the wall outlet) and expecting to get high-voltage power back
    > out the other end?
    >
    > I guess my question is answered if I know that there are no components
    > other than the transformer inside the wall wart.
    >
    > My immediate need is to use a 24VCT (center-tapped, 3-wire, 12VAC or
    > 24VAC) to convert 24VAC back up to 120VAC.


    If you attached 12 volts to the line side of the transformer, you'd get 1.2
    volts out. You'd want to go the other way to step up , but there are other
    considerations, such as the wattage you need the transformer to produce and
    what the wall wart is capable of producing
     
    RBM, Feb 7, 2009
    #2
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  3. Matt

    Phisherman Guest

    On Sat, 07 Feb 2009 17:23:32 -0600, Matt
    <> wrote:

    >Suppose I have a plug-in transformer that reduces 120VAC power to some
    >lower AC voltage (say 12VAC or 24VAC), and suppose I want to do the
    >reverse---increase a low-voltage source back up to 120VAC.
    >
    >Would there be a problem in connecting the low-voltage power to the
    >plug-in prongs of the wall wart (instead of the normal use: plugging the
    >prongs into the wall outlet) and expecting to get high-voltage power
    >back out the other end?
    >
    >I guess my question is answered if I know that there are no components
    >other than the transformer inside the wall wart.
    >
    >My immediate need is to use a 24VCT (center-tapped, 3-wire, 12VAC or
    >24VAC) to convert 24VAC back up to 120VAC.


    If you do as you say, you'll get 1.2 volts output. You need a step up
    transformer.
     
    Phisherman, Feb 7, 2009
    #3
  4. Matt

    Matt Guest

    RBM wrote:
    > "Matt" <> wrote in message
    > news:VJojl.475$...
    >> Suppose I have a plug-in transformer that reduces 120VAC power to some
    >> lower AC voltage (say 12VAC or 24VAC), and suppose I want to do the
    >> reverse---increase a low-voltage source back up to 120VAC.
    >>
    >> Would there be a problem in connecting the low-voltage power to the
    >> plug-in prongs of the wall wart (instead of the normal use: plugging the
    >> prongs into the wall outlet) and expecting to get high-voltage power back
    >> out the other end?
    >>
    >> I guess my question is answered if I know that there are no components
    >> other than the transformer inside the wall wart.
    >>
    >> My immediate need is to use a 24VCT (center-tapped, 3-wire, 12VAC or
    >> 24VAC) to convert 24VAC back up to 120VAC.

    >
    > If you attached 12 volts to the line side of the transformer, you'd get 1.2
    > volts out. You'd want to go the other way to step up , but there are other
    > considerations, such as the wattage you need the transformer to produce and
    > what the wall wart is capable of producing



    Whoops, sorry. You and Phisherman are right.

    I meant to ask what voltage I would get at the prongs if I hook low AC
    voltage to what is normally the output.
     
    Matt, Feb 8, 2009
    #4
  5. Matt

    Matt Guest

    Ralph Mowery wrote:
    > "Matt" <> wrote in message
    > news:VJojl.475$...
    >> Suppose I have a plug-in transformer that reduces 120VAC power to some
    >> lower AC voltage (say 12VAC or 24VAC), and suppose I want to do the
    >> reverse---increase a low-voltage source back up to 120VAC.
    >>
    >> Would there be a problem in connecting the low-voltage power to the
    >> plug-in prongs of the wall wart (instead of the normal use: plugging the
    >> prongs into the wall outlet) and expecting to get high-voltage power back
    >> out the other end?
    >>
    >> I guess my question is answered if I know that there are no components
    >> other than the transformer inside the wall wart.
    >>
    >> My immediate need is to use a 24VCT (center-tapped, 3-wire, 12VAC or
    >> 24VAC) to convert 24VAC back up to 120VAC.

    >
    > If it is an AC output and not a DC output wall wart then you can connect 12
    > volts to it and get out about 120 volts if it is normally a 12 volt output.
    > Just put the 12 volts to the normal 12 volt output and the prongs will have
    > 120 volts on them . You have to check to see how much current or how many
    > watts the transformer is rated for as not to overload it. If your wall wart
    > is good for 12 volts at one amp, then about all you can draw at 120 volts is
    > 1/10 of an amp.
    >
    > Usuallly transformers do not care if they are connected up either way.
    > Sometimes the output voltage will exceed the insulation of the wiring.



    Thanks.

    I am measuring about 25.7 VAC at the output when the input is 117.5 VAC.

    The thing is labeled "Plug-in class 2 transformer, Input: AC 120V 60Hz
    35W, Output: AC 24VCT 700 mA".

    So it is producing well over its nominal voltage. Can I conclude that
    it is unregulated---that it is just a plain old transformer?

    Can I expect the same _power_ capabilities in normal and reverse
    direction? Your remark about current seems to indicate that.

    It has a 3-prong (grounded) plug. What could that tell somebody about
    its innards?
     
    Matt, Feb 8, 2009
    #5
  6. Matt

    Matt Guest

    AZ Nomad wrote:
    > On Sat, 07 Feb 2009 18:49:25 -0500, Phisherman <> wrote:
    >> On Sat, 07 Feb 2009 17:23:32 -0600, Matt
    >> <> wrote:

    >
    >>> Suppose I have a plug-in transformer that reduces 120VAC power to some
    >>> lower AC voltage (say 12VAC or 24VAC), and suppose I want to do the
    >>> reverse---increase a low-voltage source back up to 120VAC.
    >>>
    >>> Would there be a problem in connecting the low-voltage power to the
    >>> plug-in prongs of the wall wart (instead of the normal use: plugging the
    >>> prongs into the wall outlet) and expecting to get high-voltage power
    >>> back out the other end?
    >>>
    >>> I guess my question is answered if I know that there are no components
    >>> other than the transformer inside the wall wart.
    >>>
    >>> My immediate need is to use a 24VCT (center-tapped, 3-wire, 12VAC or
    >>> 24VAC) to convert 24VAC back up to 120VAC.

    >
    >> If you do as you say, you'll get 1.2 volts output. You need a step up
    >> transformer.

    >
    > He'd get 120vac because he'd connect the 24VAC to the 24VAC side.
    > The problem is going to be loses and power considerations. He'll be lucky
    > if he ends up with enough power to run a clock.



    Why wouldn't the efficiency and power rating be about the same in both
    directions?
     
    Matt, Feb 8, 2009
    #6
  7. Matt

    Bryce Guest

    Matt wrote:

    > Ralph Mowery wrote:
    >> "Matt" <> wrote in message
    >> news:VJojl.475$...
    >>> Suppose I have a plug-in transformer that reduces 120VAC power to some
    >>> lower AC voltage (say 12VAC or 24VAC), and suppose I want to do the
    >>> reverse---increase a low-voltage source back up to 120VAC.
    >>>
    >>> Would there be a problem in connecting the low-voltage power to the
    >>> plug-in prongs of the wall wart (instead of the normal use: plugging the
    >>> prongs into the wall outlet) and expecting to get high-voltage power
    >>> back out the other end?
    >>>
    >>> I guess my question is answered if I know that there are no components
    >>> other than the transformer inside the wall wart.
    >>>
    >>> My immediate need is to use a 24VCT (center-tapped, 3-wire, 12VAC or
    >>> 24VAC) to convert 24VAC back up to 120VAC.

    >>
    >> If it is an AC output and not a DC output wall wart then you can connect
    >> 12 volts to it and get out about 120 volts if it is normally a 12 volt
    >> output. Just put the 12 volts to the normal 12 volt output and the prongs
    >> will have
    >> 120 volts on them . You have to check to see how much current or how
    >> many
    >> watts the transformer is rated for as not to overload it. If your wall
    >> wart is good for 12 volts at one amp, then about all you can draw at 120
    >> volts is 1/10 of an amp.
    >>
    >> Usuallly transformers do not care if they are connected up either way.
    >> Sometimes the output voltage will exceed the insulation of the wiring.

    >
    >
    > Thanks.
    >
    > I am measuring about 25.7 VAC at the output when the input is 117.5 VAC.
    >
    > The thing is labeled "Plug-in class 2 transformer, Input: AC 120V 60Hz
    > 35W, Output: AC 24VCT 700 mA".
    >
    > So it is producing well over its nominal voltage. Can I conclude that
    > it is unregulated---that it is just a plain old transformer?
    >
    > Can I expect the same _power_ capabilities in normal and reverse
    > direction? Your remark about current seems to indicate that.
    >
    > It has a 3-prong (grounded) plug. What could that tell somebody about
    > its innards?


    It is very likely just a transformer; i.e., does not provide any
    sort of voltage regulation.

    A transformer may be operated in either direction - either winding
    can be used as the input. Don't exceed the voltage or current ratings
    of either winding. It is not necessarily true that the center tap
    on the 24V winding is rated for 700ma, but it probably is.

    The ground is probably connected to the transformer core. It might
    also ground the center tap of the 24V winding. Why not use your
    ohmmeter or a battery and bulb (sigh, LED) tester to find out?
     
    Bryce, Feb 8, 2009
    #7
  8. Matt

    Guest

    On Sat, 07 Feb 2009 17:23:32 -0600, Matt
    <> wrote:

    >Suppose I have a plug-in transformer that reduces 120VAC power to some
    >lower AC voltage (say 12VAC or 24VAC), and suppose I want to do the
    >reverse---increase a low-voltage source back up to 120VAC.
    >
    >Would there be a problem in connecting the low-voltage power to the
    >plug-in prongs of the wall wart (instead of the normal use: plugging the
    >prongs into the wall outlet) and expecting to get high-voltage power
    >back out the other end?
    >
    >I guess my question is answered if I know that there are no components
    >other than the transformer inside the wall wart.
    >
    >My immediate need is to use a 24VCT (center-tapped, 3-wire, 12VAC or
    >24VAC) to convert 24VAC back up to 120VAC.



    Yes you can, but keep in mind they are only something like 80%
    efficient at best, and your maximum primary current will be the rated
    output of the device. This means a 1 amp wall wart will put out 100ma
    of current at 120 volts from a 12 volt supply.

    In an AC wall wart there is only a transformer. Don't try it with a DC
    output unit though!!!!
     
    , Feb 8, 2009
    #8
  9. On 2/7/2009 3:23 PM Matt spake thus:

    > Suppose I have a plug-in transformer that reduces 120VAC power to some
    > lower AC voltage (say 12VAC or 24VAC), and suppose I want to do the
    > reverse---increase a low-voltage source back up to 120VAC.
    >
    > Would there be a problem in connecting the low-voltage power to the
    > plug-in prongs of the wall wart (instead of the normal use: plugging the
    > prongs into the wall outlet) and expecting to get high-voltage power
    > back out the other end?
    >
    > I guess my question is answered if I know that there are no components
    > other than the transformer inside the wall wart.
    >
    > My immediate need is to use a 24VCT (center-tapped, 3-wire, 12VAC or
    > 24VAC) to convert 24VAC back up to 120VAC.


    You might be interested in this guy's pages:

    http://www.dogstar.dantimax.dk/tubestuf/index.htm

    He builds vacuum tube circuits, and some of them are powered by 2
    wall-warts back-to-back, just as you're asking about, like this power
    supply used for one of his projects:

    http://www.dogstar.dantimax.dk/tubestuf/sappower.htm

    This circuit supplies more than 400 volts of B+ for a small tube
    amplifier (using a voltage tripler), as well as several other voltages.
    So yes, it can be done.


    --
    Personally, I like Vista, but I probably won't use it. I like it
    because it generates considerable business for me in consulting and
    upgrades. As long as there is hardware and software out there that
    doesn't work, I stay in business. Incidentally, my company motto is
    "If this stuff worked, you wouldn't need me".

    - lifted from sci.electronics.repair
     
    David Nebenzahl, Feb 8, 2009
    #9
  10. Matt

    Matt Guest

    mm wrote:
    > On Sat, 07 Feb 2009 18:34:52 -0600, Matt
    > <> wrote:
    >
    >> Ralph Mowery wrote:
    >>> "Matt" <> wrote in message
    >>> news:VJojl.475$...
    >>>> Suppose I have a plug-in transformer that reduces 120VAC power to some
    >>>> lower AC voltage (say 12VAC or 24VAC), and suppose I want to do the
    >>>> reverse---increase a low-voltage source back up to 120VAC.


    > Why do you want to do this, btw. Is there no 110 outlet at that
    > location? Maybe you can run one.



    Trying to switch a relay that has a 120VAC coil using a nominal 24VAC
    signal from a digital HVAC thermostat. I don't have a relay with a
    24VAC coil handy.
     
    Matt, Feb 8, 2009
    #10
  11. Matt

    Bryce Guest

    mm wrote:

    > On Sun, 08 Feb 2009 01:10:22 -0600, Matt
    > <> wrote:
    >
    >>mm wrote:
    >>> On Sat, 07 Feb 2009 18:34:52 -0600, Matt
    >>> <> wrote:
    >>>
    >>>> Ralph Mowery wrote:
    >>>>> "Matt" <> wrote in message
    >>>>> news:VJojl.475$...
    >>>>>> Suppose I have a plug-in transformer that reduces 120VAC power to
    >>>>>> some lower AC voltage (say 12VAC or 24VAC), and suppose I want to do
    >>>>>> the reverse---increase a low-voltage source back up to 120VAC.

    >>
    >>> Why do you want to do this, btw. Is there no 110 outlet at that
    >>> location? Maybe you can run one.

    >>
    >>
    >>Trying to switch a relay that has a 120VAC coil using a nominal 24VAC
    >>signal from a digital HVAC thermostat. I don't have a relay with a
    >>24VAC coil handy.

    >
    > Well, you can measure the resistance of the 120volt relay, and from
    > that do a pretty good calculation of the current it will draw, and
    > compare that with what I said would come out of the reversed
    > transformer.
    >
    > I think I said 300 ma and 8 watts, but you can check. But that was
    > when I guessed the first transformer was 1500 ma, and someone said it
    > was half that.
    >
    > So that should give you a good idea of whether it would work, and then
    > you can try it and see. It shouldn't take long to try it.
    >
    > And then if you have to you can get a 24vac relay. I think they are
    > easily found.


    Coil current with AC applied will be much lower than the value
    calculated from DC resistance ... by perhaps a factor of ten or more.
    Inductive reactance is the dominant contributor to impedance here
    and it is proportional to frequency and isn't there at DC.

    I agree with mm's comment about 24vac relays. Your HVAC thermostat
    may have a solid-state relay driver that won't be happy with the
    unexpected load.
     
    Bryce, Feb 8, 2009
    #11
  12. On 2/8/2009 4:13 PM Ralph Mowery spake thus:

    > "mm" <> wrote in message >>
    >
    >>>Coil current with AC applied will be much lower than the value
    >>>calculated from DC resistance ... by perhaps a factor of ten or more.

    >>
    >> Even at only 60 Hertz?
    >>
    >>>Inductive reactance is the dominant contributor to impedance here
    >>>and it is proportional to frequency and isn't there at DC.
    >>>
    >>>I agree with mm's comment about 24vac relays. Your HVAC thermostat
    >>>may have a solid-state relay driver that won't be happy with the
    >>>unexpected load.

    >
    > Probably not 10 times but more like 3 or 4 times more reactance than
    > resistance for the relays.


    As pointed out, at a low frequency like 60 cps*, DC resistance =
    impedance to a good first approximation (in other words, close enough
    for gov't. work).

    * Cycles per second, the true measure of frequency. What's this "hertz"
    bullshit? Since when did a car-rental company come into the picture?


    --
    Personally, I like Vista, but I probably won't use it. I like it
    because it generates considerable business for me in consulting and
    upgrades. As long as there is hardware and software out there that
    doesn't work, I stay in business. Incidentally, my company motto is
    "If this stuff worked, you wouldn't need me".

    - lifted from sci.electronics.repair
     
    David Nebenzahl, Feb 9, 2009
    #12
  13. Matt

    Guest

    On Sun, 08 Feb 2009 01:10:22 -0600, Matt
    <> wrote:

    >mm wrote:
    >> On Sat, 07 Feb 2009 18:34:52 -0600, Matt
    >> <> wrote:
    >>
    >>> Ralph Mowery wrote:
    >>>> "Matt" <> wrote in message
    >>>> news:VJojl.475$...
    >>>>> Suppose I have a plug-in transformer that reduces 120VAC power to some
    >>>>> lower AC voltage (say 12VAC or 24VAC), and suppose I want to do the
    >>>>> reverse---increase a low-voltage source back up to 120VAC.

    >
    >> Why do you want to do this, btw. Is there no 110 outlet at that
    >> location? Maybe you can run one.

    >
    >
    >Trying to switch a relay that has a 120VAC coil using a nominal 24VAC
    >signal from a digital HVAC thermostat. I don't have a relay with a
    >24VAC coil handy.

    Get one. They are very common, plentiful, and cheap. If you were in
    Kitchener Waterloo I'd GIVE you one.
     
    , Feb 9, 2009
    #13
  14. Matt

    Matt Guest

    wrote:
    > On Sun, 08 Feb 2009 01:10:22 -0600, Matt
    > <> wrote:
    >
    >> mm wrote:
    >>> On Sat, 07 Feb 2009 18:34:52 -0600, Matt
    >>> <> wrote:
    >>>
    >>>> Ralph Mowery wrote:
    >>>>> "Matt" <> wrote in message
    >>>>> news:VJojl.475$...
    >>>>>> Suppose I have a plug-in transformer that reduces 120VAC power to some
    >>>>>> lower AC voltage (say 12VAC or 24VAC), and suppose I want to do the
    >>>>>> reverse---increase a low-voltage source back up to 120VAC.
    >>> Why do you want to do this, btw. Is there no 110 outlet at that
    >>> location? Maybe you can run one.

    >>
    >> Trying to switch a relay that has a 120VAC coil using a nominal 24VAC
    >> signal from a digital HVAC thermostat. I don't have a relay with a
    >> 24VAC coil handy.

    > Get one. They are very common, plentiful, and cheap. If you were in
    > Kitchener Waterloo I'd GIVE you one.



    Shucks, I wish I were there ... but would it handle say 20A @ 120VAC?
    To run a heater. I just paid $20 for a 30A relay, waiting for it to get
    here ...
     
    Matt, Feb 9, 2009
    #14
  15. On 2/8/2009 4:44 PM Ralph Mowery spake thus:

    > "David Nebenzahl" <> wrote in message
    > news:498f75b1$0$2715$...
    >
    >> On 2/8/2009 4:13 PM Ralph Mowery spake thus:
    >>
    >>> "mm" <> wrote in message >>
    >> >
    >>>>>Coil current with AC applied will be much lower than the value
    >>>>>calculated from DC resistance ... by perhaps a factor of ten or more.
    >>>>
    >>>> Even at only 60 Hertz?
    >>>>
    >>>>>Inductive reactance is the dominant contributor to impedance here
    >>>>>and it is proportional to frequency and isn't there at DC.
    >>>>>
    >>>>>I agree with mm's comment about 24vac relays. Your HVAC thermostat
    >>>>>may have a solid-state relay driver that won't be happy with the
    >>>>>unexpected load.
    >>>
    >>> Probably not 10 times but more like 3 or 4 times more reactance than
    >>> resistance for the relays.

    >>
    >> As pointed out, at a low frequency like 60 cps*, DC resistance = impedance
    >> to a good first approximation (in other words, close enough for gov't.
    >> work).

    >
    > When the reactance is 3 or more times the DC resistance that is nowhere near
    > enough for gov't work. The coil will smoke if you use the DC resistance
    > even at 60 cps. if the power supply will put out the current.


    Nonsense.

    Don't believe me? Get ahold of an 8 ohm speaker and measure the
    resistance (DC resistance) using a DMM. It'll be within 10% of 8 ohms,
    which is the rated *impedance*. And this covers the audio spectrum (up
    to 20 kHz).

    > Oops , forgot about the big bailout going on now by the government and the
    > big crash that is going on now. That banking and loan calculations were
    > good enough for gov't. work.


    It's a figure of speech, my man.


    --
    Personally, I like Vista, but I probably won't use it. I like it
    because it generates considerable business for me in consulting and
    upgrades. As long as there is hardware and software out there that
    doesn't work, I stay in business. Incidentally, my company motto is
    "If this stuff worked, you wouldn't need me".

    - lifted from sci.electronics.repair
     
    David Nebenzahl, Feb 9, 2009
    #15
  16. Matt

    Guest

    On Sun, 08 Feb 2009 19:18:20 -0600, Matt
    <> wrote:

    > wrote:
    >> On Sun, 08 Feb 2009 01:10:22 -0600, Matt
    >> <> wrote:
    >>
    >>> mm wrote:
    >>>> On Sat, 07 Feb 2009 18:34:52 -0600, Matt
    >>>> <> wrote:
    >>>>
    >>>>> Ralph Mowery wrote:
    >>>>>> "Matt" <> wrote in message
    >>>>>> news:VJojl.475$...
    >>>>>>> Suppose I have a plug-in transformer that reduces 120VAC power to some
    >>>>>>> lower AC voltage (say 12VAC or 24VAC), and suppose I want to do the
    >>>>>>> reverse---increase a low-voltage source back up to 120VAC.
    >>>> Why do you want to do this, btw. Is there no 110 outlet at that
    >>>> location? Maybe you can run one.
    >>>
    >>> Trying to switch a relay that has a 120VAC coil using a nominal 24VAC
    >>> signal from a digital HVAC thermostat. I don't have a relay with a
    >>> 24VAC coil handy.

    >> Get one. They are very common, plentiful, and cheap. If you were in
    >> Kitchener Waterloo I'd GIVE you one.

    >
    >
    >Shucks, I wish I were there ... but would it handle say 20A @ 120VAC?
    >To run a heater. I just paid $20 for a 30A relay, waiting for it to get
    >here ...

    No, it is rated at 15 amps, I think.
     
    , Feb 9, 2009
    #16
  17. Matt

    Guest

    On Sat, 07 Feb 2009 17:23:32 -0600, Matt
    <> wrote:

    >Suppose I have a plug-in transformer that reduces 120VAC power to some
    >lower AC voltage (say 12VAC or 24VAC), and suppose I want to do the
    >reverse---increase a low-voltage source back up to 120VAC.
    >
    >Would there be a problem in connecting the low-voltage power to the
    >plug-in prongs of the wall wart (instead of the normal use: plugging the
    >prongs into the wall outlet) and expecting to get high-voltage power
    >back out the other end?
    >
    >I guess my question is answered if I know that there are no components
    >other than the transformer inside the wall wart.
    >
    >My immediate need is to use a 24VCT (center-tapped, 3-wire, 12VAC or
    >24VAC) to convert 24VAC back up to 120VAC.


    You know of course that it can only handle very small current
    levels and that it would need the original output circuits would will
    be handling 120V when they are only insulated for 12Volt

    In short, it is a bad ideal Get the right tool for the job.


    Joseph E Meehan
     
    , Feb 9, 2009
    #17
  18. Yes, and AC output wall wart should provide the needed
    voltages. However, we don't know if the application would
    work just fine. How many watts of 24 VAC do you have, and
    how many watts of 110 VAC do you need?

    Should be able to convert 24 VC to 110 VAC. You won't have
    much amperage to use, on the 110 VAC side.

    --
    Christopher A. Young
    Learn more about Jesus
    www.lds.org
    ..


    "Matt" <> wrote in message
    news:VJojl.475$...
    Suppose I have a plug-in transformer that reduces 120VAC
    power to some
    lower AC voltage (say 12VAC or 24VAC), and suppose I want to
    do the
    reverse---increase a low-voltage source back up to 120VAC.

    Would there be a problem in connecting the low-voltage power
    to the
    plug-in prongs of the wall wart (instead of the normal use:
    plugging the
    prongs into the wall outlet) and expecting to get
    high-voltage power
    back out the other end?

    I guess my question is answered if I know that there are no
    components
    other than the transformer inside the wall wart.

    My immediate need is to use a 24VCT (center-tapped, 3-wire,
    12VAC or
    24VAC) to convert 24VAC back up to 120VAC.
     
    Stormin Mormon, Feb 9, 2009
    #18
  19. I think you'll find that on most 110 VAC wall warts, the
    110 VAC side is insulated for 110 VAC.

    --
    Christopher A. Young
    Learn more about Jesus
    www.lds.org
    ..


    <> wrote in message
    news:...

    You know of course that it can only handle very small
    current
    levels and that it would need the original output circuits
    would will
    be handling 120V when they are only insulated for 12Volt

    In short, it is a bad ideal Get the right tool for the job.


    Joseph E Meehan
     
    Stormin Mormon, Feb 9, 2009
    #19
  20. Matt

    Guest

    On Mon, 09 Feb 2009 08:27:26 -0500, wrote:

    >On Sat, 07 Feb 2009 17:23:32 -0600, Matt
    ><> wrote:
    >
    >>Suppose I have a plug-in transformer that reduces 120VAC power to some
    >>lower AC voltage (say 12VAC or 24VAC), and suppose I want to do the
    >>reverse---increase a low-voltage source back up to 120VAC.
    >>
    >>Would there be a problem in connecting the low-voltage power to the
    >>plug-in prongs of the wall wart (instead of the normal use: plugging the
    >>prongs into the wall outlet) and expecting to get high-voltage power
    >>back out the other end?
    >>
    >>I guess my question is answered if I know that there are no components
    >>other than the transformer inside the wall wart.
    >>
    >>My immediate need is to use a 24VCT (center-tapped, 3-wire, 12VAC or
    >>24VAC) to convert 24VAC back up to 120VAC.

    >
    > You know of course that it can only handle very small current
    >levels and that it would need the original output circuits would will
    >be handling 120V when they are only insulated for 12Volt
    >
    > In short, it is a bad ideal Get the right tool for the job.
    >
    >
    > Joseph E Meehan

    You are mis-reading him. The low voltage goes IN the low voltage
    side, making the high voltage go out the high voltage side so
    everything is operating within it's design parameters insulation-wise.
     
    , Feb 9, 2009
    #20
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