high frequency transformer on 60hz

[OwaisAhmed]

i was looking for low voltage ac supply transformer. that i can use on breadboard to practice about what i learn. so i had a lcd smps i took a transformer from it that convert 220 ac to 12v and 5v. i know that those transformer work on around 300khz frequency. so if i run this on 60hz. what could be the problems and why frequency matter in transformer. i actually tried it shows around 2 to 2.5v on ouput.

[TimFox]

High frequency transformers have lower inductance than low frequency transformers.  The “magnetizing” inductance (approximately equal to the self-inductance of the primary winding) is in parallel with the ideal transformer’s primary;  the low inductance of the h.f. unit essentially shorts out the primary at low frequency.
Check out the internet on transformer models, including “magnetizing” and “leakage” inductances to get a feel for frequency effects.

[bob91343]

It's almost a certainty that running a transformer on a much lower frequency will result in disaster.  The core will saturate immediately, causing high current limited only by winding resistance.  First the explosion, then the smoke.

[Circlotron]

The voltage a transformer will tolerate varies approximately with the frequency supplied to it. A transformer from a 220VAC SMPS would likely have +/- 300V applied to the primary, and if it was designed for 300kHz then it might only tolerate (60Hz/300,000Hz) x 300V = 0.06V. Not much all. Probably an oversimplification, but you get the general idea.

[Kim Christensen]

If you just want a source of low voltage AC to experiment with as a hobbyist, then look into getting a wallwart with an AC output. (No rectifier/cap inside):

https://www.allelectronics.com/category/912/ac-ac-wall-adapters/1.html
(Not endorsing this site. Just an example)