how to lower ac voltage?

Discussion in 'General Electronics Chat' started by mighty12, Oct 5, 2009.

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  1. mighty12

    Thread Starter New Member

    Sep 10, 2009
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    is it possible to lower ac voltage for about 20 volts without using a transformer.
    for exmple a 240 vac will become 220vac..... i have considered triac
    but ive read it is not advisable for electronic devices..
     
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  2. steinar96

    Active Member

    Apr 18, 2009
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    I dont think there are any viable options without a transformer. You could dissipate it trough some resistance but that's not advisable and depends on the current you are drawing and the resistance of the load. Why are you unable to use a transformer ?
     
  3. Wendy

    Moderator

    Mar 24, 2008
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    Sure, you can use a low ohmage resistor, a coil, or a capacitor in series, depending on the load. So what is the load?
     
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  4. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    On old trick: use a relatively small step-down transformer to buck or boost an AC output voltage by a small amount. The transformer's secondary winding must be rated at or greater than the output current required by the load. The output will be raised or lowered by the transformer's secondary voltage, depending on its phase relationship to the primary. If it boosts, swap the secondary leads and it will buck. It's smaller than a 240VAC>220VAC transformer with the same load.

    Ken
     
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  5. mighty12

    Thread Starter New Member

    Sep 10, 2009
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    @KMoffett i just wanna know how long should the transformer will be fine if i used it continously 24/7. if my load is about 1 amp what rating of transformer should i use.? would it last for a year?
     
  6. ol'trusty

    Member

    Sep 9, 2009
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    depending on your load but you can look into using an adjustable ssr. I have used them before
     
  7. Wendy

    Moderator

    Mar 24, 2008
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    Use a transformer rated for an amp or over. It is a cool concept.
     
  8. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    What Bill said...and it will last as long as any other transformer.

    "an adjustable ssr" (dimmer?), is OK for some resistive load applications such as lights and heaters, but not a good choice for inductive loads like induction motors.

    mighty12, what's your load?

    Ken



    Ken
     
  9. Lin0

    New Member

    Jan 13, 2015
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    What if mighty12's load was 260 watts @120volts and wanted to reduce the voltage to 111volts ac?
     
  10. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Lin0,

    What's your load? Is it a secret?

    Ken
     
  11. Lin0

    New Member

    Jan 13, 2015
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    Ah, seems people have different ways of answering this question. To me, if one asks me what the load is - that implies what the electrical load specifications are - which I've answered. Maybe you want to know what device the 120volts is traveling into? If that is the case then all it is, is a slow cooker.
     
  12. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Lin0,

    What you said in your first post is key to a good solution. Triacs are not recommended for [some] electronic devices like motors, but work OK for resistive devices Since you never said your load is a slow cooker, which is a resistive heater, we could not give you a totally knowledgeable answer. Just speculation. A triac dimmer with the proper voltage (>240VAC) and current/wattage rating should work fine.

    Ken
     
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  13. Lin0

    New Member

    Jan 13, 2015
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    Ken,
    Thank you for clarifying and for the correspondence. I hope to add value to this forum in the future as I learn more.
     
  14. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Happy to help. I've been in electronics since I was 12...that's %$!* years ago. I hang out here as much to learn, as to help. If you follow this Forum you'll see how important it is to give as much detail as possible when asking a question. The administrator doesn't charge by the work! ;)

    Ken
     
  15. alfacliff

    Well-Known Member

    Dec 13, 2013
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    a slow cooker is a resistive load, and a triac light dimmer would work ok for that. the reason for all the questions about the load is that different loads have to be treated differently. an inductive load, like a transformer or motor, flourescent lights, incandesant lamps, all need to have the voltage supplied different.
     
  16. #12

    Expert

    Nov 30, 2010
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    Puleeze! This is a 2009 thread. Mighty12 probably isn't watching today.
     
  17. bertus

    Administrator

    Apr 5, 2008
    15,648
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    Hello,

    Mighty12's last activity was in okt 2010.
    He is long gone.

    Bertus
     
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