advantage and disadvatnge of AC to DC converter circuit

[pharaon]

Neither. Select a more appropriate and safer circuit to power the fan

i don't want to use transformer

 

[duke37]

i don't want to use transformer

Tough

Also, you cannot use two capacitors in series to use a higher voltage since one capacitor may take most of the voltage and the other very little. The normal solution is to put a potential divider to the midpoint. I made a large power supply with two capacitors in series and two resistors in series to share the voltage. One of the resistors failed. The bang as a capacitor exploded was quite impressive.

 

[Harald Kapp]

Neither. Select a more appropriate and safer circuit to power the fan.

I repeat:
1) Do not, never, use this type of "power supply". This is a cheap technique intended to be used in fully isolated housings at best. As soon as there is the slightest risk of exposure of one of the output leads to human touch there is also a risk of a potentially deadly shock. You obviously lack the experience to judge this circuit. Therefore it is mandatory that you use a save power supply.

I mean it.

 

[bertus]

Hello,

Why not use a simple adapter:
https://www.ebay.com/itm/Power-Supp...hash=item3655dd5b7f:m:m0o-snNRN6jjDSu3iOp6T2w
They are cheap and safe.

Bertus

 

[pharaon]

slightest risk of exposure of one of the output leads

do you mean the DC 12V output leads?

 

[bertus]

Hello,

Yes, as there is no isolation transformer, the 12 volt leads are directly in contact with the mains.

Bertus

 

[pharaon]

i want something small to put inside a fridge

 

[bertus]

Hello,

What size of fan do you want to use?
There are also many 230 Volts fans available.
EBMpapst and etri are well known brands for them.

Bertus

 

[pharaon]

this size
also EBMpapst and etri does not exist in my country and if it does it will be expensive

 

[Harald Kapp]

i want something small to put inside a fridge

A wall wart is small.

 

[pharaon]

any other transform-less way?

 

[Ylli]

Many of the modern 'Wall Worts' do not contain a bulky conventional transformer. They incorporate a switching power supply that uses a much smaller transformer operating at a relatively high frequency, so they can provide isolation in a small space. Here is 12V 3A unit that will handle any small fan you throw at it: https://www.amazon.com/Chanzon-Swit...d=1590082669&sprefix=12+volt+,aps,173&sr=8-30

 

[WHONOES]

Don't

 

[pharaon]

Don't

have you tried it before?

 

[WHONOES]

It is not safe. If you touch any of the wires, instant death will result. I don't need to try it, common sense and 50 years in electronics is all I need to offer the warning given.

 

[bertus]

Hello,

Looking at this page:
https://www.ebay.com/itm/10-ten-x-4...147103?hash=item1a21daf3df:g:6icAAOSwA3dYUZRT
The fan is drawing 0.16 A.
A 0.5 A adapter (wall wart) will do nicely:
https://www.ebay.com/itm/12V-5V-0-5...hash=item1a320d988b:m:m2hJIc29RHpquHUESUcim9Q

Bertus

 

[pharaon]

It is not safe. If you touch any of the wires, instant death will result. I don't need to try it, common sense and 50 years in electronics is all I need to offer the warning given.

ok but can i ask how can the output 12v dc cause shock? isn't it just 12v?

 

[Ylli]

It is 12 volts (or 9 volts with the given zener) between the two output leads. But it can be as much as 230VAC between either of the output leads and a grounded object. So it you touch *either* of the output leads, that is no different than touching one of the leads on the wall outlet.

 

[Cirkit]

i'm gonna use 12 dc fan one of those like pc fan inside my old fridge to make good coolant , and will connect it to the thermostat to run and stop as the fridge work so i need something small

The small fan isn't going to have much effect in the fridge. You'll just be blowing the cold air towards one surface.

Do you intend to connect the fan to the fridge thermostat? It might be easier to use a mains powered fan instead as mentioned above.

 

[duke37]

Any energy that you put in to drive the fan will need to be extracted by the fridge, So use as little as possible.Even a very low air movement will increase the heat transfer coefficient considerably.