safest way to drive a transformer with 130v primary

[amateur_24]

Hi
I trying to design myself a linear psu using a 24v rms center tapped transformer upto 20v around 2A. It's digitally controlled so it needs a 3.3v supply. Due to being a linear supply I've put in a 12v fan. The easiest way to implement this AFAIK is to use one of these transformers that have a 5v and 12v secordary then regulate it to 3.3v and 12v resopectively

However am an amateur as my name suggests. Why is the input voltage 265v but the primary 65 to 130v? Is the pimrary not where the input voltage goes? Any help on a driver would be appreciated

Here's a link to the transformer am thinking of using
https://uk.farnell.com/myrra/74000/transformer-ee16-4w/dp/1214644

 

[MikeMl]

What is driving the primary? 120V or 240V ? 50 or 60 Hz?

If one of the above, this transformer is not a "power" transformer to be used in a "linear" supply"; rather is a "flyback" transformer used in switching power supplies.

What are you building?

 

[amateur_24]

yeah after studying the specification more it said it need 100Khz which is normal frequency for a switch mode psu. Also mensioned it need a offline switcher. I've decided not go down that route even though I can get hold of the transformer
much cheaper. I don't trust my cheapo multimeter at 400vdc.

I was thinking of using this as a convient way of having a 5v and 12 volt supply. My problem is the power transformer (230v mains) am using outputs around 32v dc after recfification. 5v and 12v can't be made using just a linear reg. I can't seem to find a switching reg that can output 12 and 5v. I was originally thinking of using a 9v pcb mount power transformer that would give me around 12v dc after rectification. Unless anyone can think of something else? The 32v is mean't to power the main adjustable regulator to give around 0-30v dc output.

 

[jpanhalt]

Years ago, I started with a wall wart as my PSU. It was from Jameco, as I remember, branded by Motorola, and provided 5V DC, 12V DC and -12V DC. It was very cheap, but the specific unit is no longer available. It served me for more than an decade, and I still use it.

I suggest you look at:

Jameco.com
MPJA.com

for something that will meet your needs or start with a PC power supply, for which there an innumerable posts on the Internet.

This is certainly one situation when posting your location would help us give more specific advice.

John