How do i convert 220v to 12v without a transformer

nelson64 over 2 years ago

I am trying to build a circuit with a transformer to put in 220v to get 12v and if possible get 5v out to

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scottiebabe over 2 years ago in reply to michaelkellett +3

Yes.. Perhaps E14 produce a learning module on clairvoyance so we can all do better
michaelkellett over 2 years ago in reply to Jan Cumps +2

It's a Schrödinger Transformer. MK
Jan Cumps over 2 years ago +2

The most used method is to use a capacitive dropper. It can reduce the mains to a manageable voltage with little loss, You need to know the impedance of your load to calculate the capacitive dropper's…

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michaelkellett over 2 years ago

Do you need isolation ?

Some mains powered devices do not need isolation in an internal low voltage power supply. Unless you are very confident that the whole system will be safe you should use a transformer.

What is your 12V for, how much power, AC or DC etc.

MK
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nelson64 over 2 years ago in reply to michaelkellett

It is to run a water pump of 12v dc and timer that use 5v
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michaelkellett over 2 years ago in reply to nelson64

Definitely best to use a ready made 12V supply. Your water pump may draw a much higher current when it starts up than its steady state power rating might lead you to expect.

Low frequency based transformer based power supplies are often quite good at this but switchers may have trouble. Kind of hard to tell without just trying it because pumps and power supplies at the low end of the market are not usually specified in detail in this regard.

If the water pump is small just get a power supply that can deliver 4x the nominal pump power.

You can make the 5V with a regulator from the 12V supply, you can buy one from Amazon or Ebay if looking for cheapness. For simplicity just use a second DC supply.

MK
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Jan Cumps over 2 years ago in reply to nelson64

Water and a power supply without transformer are enemies. Go for a solution with a transformer.
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kmikemoo over 2 years ago in reply to Jan Cumps

I was leaning to the same point but for the motor inrush. Use a buck autotransformer and maintain your neutral bond. Helps to trip the breaker if something goes wrong.
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kmikemoo over 2 years ago in reply to Jan Cumps

I was leaning to the same point but for the motor inrush. Use a buck autotransformer and maintain your neutral bond. Helps to trip the breaker if something goes wrong.
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