Transformer Issues! - multiple windings and tabs

[Unmesh Sawant]

I wanted to use ac source in my diy soldering station, i found a 24v 3 amp transformer but the problem is i am not able to figure out the pinouts for it. I will upload a pic of it so that you may know how it looks.

Thanks in Advance
Unmesh.

 

[KlausST]

Hi,

usually a transformaer has two windings: primary and secondary.

Primary its for mains power input. it has thin wires and a lot of turns
Secondary is the 24V output. Thick wires and less turns.

******
Don´t you have a printing, partnumber, ordering number, datasheet, description, vendor, internet site?

Klaus

 

[BradtheRad]

Perhaps it has the option to accept 120VAC or 240VAC. Find the windings that are highest ohm. These are for house voltage. You must figure out how to wire them in series, so they handle mains AC voltage.

Your transformer appears to have 14 tabs. Is this correct?

You may need to combine secondaries, so that you get total 24V 3A. But which secondaries? You might end up with 48V 1A. Or 12V 6A. Etc. This is a challenge, and you may need to do a lot of experiments, so you find the correct combination.

 

[schmitt trigger]

Where did you find the transformers? at a surplus place on the web?
Don't they have spec sheet?

The problem with split windings is to figure out the proper phasing. If connected incorrectly, you will create a short. When performing your experiments, always place a 1/2 amp slow blow fuse in series before you plug the transformer to the mains.

 

[Unmesh Sawant]

My transformer has in total 8 tabs, but how do i know which is mains and which are output tabs as it is not wired its a barebone transformer, i will provide a link of the transformer from where did i buy it.

https://www.electroncomponents.com/...rmers-Power-Supply/24v-3amp-Transformer-3A-HD.

 

[andre_luis]

Are you sure that all the tabs are internally connected to wires on the reel ?
Did you check if there is dupplicated tabs to the same winding ?

 

[schmitt trigger]

The website really does not include a proper specification.


The website offers a golden nugget though:
voltage: 2 x 12V

This appears to mean that you have two independent 12 volt secondaries which you could connect either in series or parallel.
Also, it is implied that the transformer *only* works from 230 volts...in other words, it is not an universal 230/115 volt device.

This simplifies things *a lot*.
As suggested earlier, find the terminals with the thin wire; those will be your 230 volt input. You can safely connect them to the mains.
Then with a multimeter, identify the pair of secondary 12 volt windings. NOTE: with no load the output voltage will be around 16 volts, that is perfectly normal.

Now, take one terminal from one of the secondary 12 volt windings and connect it to any other terminal of the other 12 volt winding.
Power up the transformer and take a reading with the multimeter across the free terminals. If the voltage is between 24 to 32 volts, congratulations, you have it made.

On the other hand, if the voltage is zero or very close to zero, unpower the transformer, and swap one terminal of only one of the windings.
Power again and measure...your voltage should be there.

For the next time you purchase a component, a lesson learned:
The lesson I've learned over the years not to purchase anything from the web which does not include a proper datasheet or drawing....unless it is so cheap you can afford to damage it during the course of your experiments.

 

[D.A.(Tony)Stewart]

Also consider a light dimmer for temp control.

 

[andre_luis]

Power up the transformer and take a reading with the multimeter across the free terminals

Never needless to say, if you are not totally sure of what are doing, to be cautious during testings, not directly connecting the stuff to the mains. Feeding the wrong windings of this transformer with 220v could not only burn the part itself, but also generate an output of more than 1,000 volts. In general it is recommended to use a known AC took from another transformer, just to identify the function of each wire.