how to lower ac voltage?

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mighty12

Joined Sep 10, 2009
3
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..
 

steinar96

Joined Apr 18, 2009
239
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 ?
 

Wendy

Joined Mar 24, 2008
21,840
Sure, you can use a low ohmage resistor, a coil, or a capacitor in series, depending on the load. So what is the load?
 

KMoffett

Joined Dec 19, 2007
2,766
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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Thread Starter

mighty12

Joined Sep 10, 2009
3
@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?
 

Wendy

Joined Mar 24, 2008
21,840
@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?
Use a transformer rated for an amp or over. It is a cool concept.
 

KMoffett

Joined Dec 19, 2007
2,766
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
 

Lin0

Joined Jan 13, 2015
3
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
What if mighty12's load was 260 watts @120volts and wanted to reduce the voltage to 111volts ac?
 

Lin0

Joined Jan 13, 2015
3
Lin0,

What's your load? Is it a secret?

Ken
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.
 

KMoffett

Joined Dec 19, 2007
2,766
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
 

Lin0

Joined Jan 13, 2015
3
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
Ken,
Thank you for clarifying and for the correspondence. I hope to add value to this forum in the future as I learn more.
 

KMoffett

Joined Dec 19, 2007
2,766
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
 

alfacliff

Joined Dec 13, 2013
2,449
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.
 

#12

Joined Nov 30, 2010
18,076
Puleeze! This is a 2009 thread. Mighty12 probably isn't watching today.
 
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