Alternate capacitor help

[arunskumar05]

I am building a transformerless power supply of output 12v 100ma,the capacitor c1 used in the circuit is a 2.2 mfd(225k) mylar capacitor which is difficult to find in my nearby local market...
my question is that can i use the ceiling fan capacitor(2.5mfd,440v) in place of c1..
ceiling fan capacitor is available everywhere..
please refer the attached circuit diagram..

 

[JimB]

If you are really intent on building that circuit, then the 2.5μF capacitor will work.
The components of the circuit will run hotter, there will be more power dissipated in the resistors and the zener diode.

Take note of the warning on the schematic!

This warning also applies to ANYTHING connected to the output of this circuit.
What do you intend powering from this circuit?
Unless it is all enclosed in an insulated box - DON'T DO IT.

JimB

 

[Dean Huster]

Listen to JimB. That is an extraordinarily dangerous circuit that's connected directly to the mains. Safe supplies generally have some kind of transformer isolation either "up front" as with the older traditional "linear/analog" supplies or somewhere mid-circuit as with most switching supplies, such as those in our modern desktop computers.

 

[tvtech]

Hi Guys

Your warnings about this type of circuit are 100% correct. You have to know what you are doing when working with/on stuff like this.

Suffice to say....and this is important...if the circuitry is handled correctly and the designer is aware of the risks involved and the outer casing is good...you will end up with a product that is exceptionally reliable...

Doable..but not for experimenters.

So whilst I am a huge supporter of this simple and reliable way of reducing mains voltage....I don't actively promote it.

I don't want to kill a member here.

On another note though...I know of another popular Forum that has banned transformerless power supply discussion or posts. Heck, at least here at ETO we explain WHY they are dangerous.

BUT, these little supplies are amazingly robust and good at what they do used the right way.

Just me,
tvtech

 

[dr pepper]

The motor capacitor would work, a mylar cap should you find one has to be x rated or y rated to connect to the mains.
Your schematic doesnrt show a fuse, you need one.
Both - and + outputs from the supply are potentially dangerous.

 

[chemelec]

please refer the attached circuit diagram..

In North America, typically our Power has a Hot and Neutral plus a Ground.
Not sure this is true for Europe and other Countries that have 220 to 240 VAC @50 Hz.???

These types of circuits are Less Dangerous, IF your Line Voltage actually has a Neutral and Hot.
And IF You wire these Appropriately to this Circuit.

Also, I believe the 1 Watt Zener is Too low of a Rating.
I would Recommend a 5 Watt Zener.
And at least one fuse on the mains input.