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Electronics => Beginners => Topic started by: fixit7 on June 04, 2019, 11:10:31 pm

Title: Are those switching transformers
Post by: fixit7 on June 04, 2019, 11:10:31 pm

Are those both switching transformers?

https://www.dropbox.com/s/z5dqd7lacwrzq9w/SwitchingTransformer.png?dl=0 (https://www.dropbox.com/s/z5dqd7lacwrzq9w/SwitchingTransformer.png?dl=0)

Thanks.

Title: Re: Are those switching transformers
Post by: Stray Electron on June 04, 2019, 11:25:12 pm

  You might bet more replies if you used a picture host that doesn't require that we join and log into.

Title: Re: Are those switching transformers
Post by: fixit7 on June 05, 2019, 12:25:36 am

(http://i64.tinypic.com/2l930w6.png)

Title: Re: Are those switching transformers
Post by: ArthurDent on June 05, 2019, 12:39:22 am

Front looks like switching transformer, rear one is A.C. line common mode choke.

Title: Re: Are those switching transformers
Post by: fixit7 on June 05, 2019, 01:52:28 am

Thanks for the help.

Andy

Title: Re: Are those switching transformers
Post by: strawberry on June 05, 2019, 06:49:32 am

Quote from: ArthurDent on June 05, 2019, 12:39:22 am

Front looks like switching transformer, rear one is A.C. line common mode choke.

It is flyback topology swithcing mode power supply. It is not exactly a transformer but gapped inductor with secundary winding. Its output voltage is not determined by turns ratio

Title: Re: Are those switching transformers
Post by: fixit7 on June 05, 2019, 12:59:45 pm

Thanks.

Quote

Switch mode power supplies

An SMPS, or switcher, is a power source that uses a switching regulator to maintain stable output voltage(s) from an AC or DC source. The switching regulator uses one or more semiconductor devices, such as a bipolar junction transistor, MOSFET or IGBT, switching between ‘On’ and ‘Off’ states to maintain output voltage regulation. These devices can operate with fixed ‘On’ time and variable frequency, or more commonly, at a fixed frequency and variable duty cycle. High efficiency results from the low power dissipation of the switching device when it is either ‘On’ or ‘Off’. The device dissipates power only during the transitions between states. Also, because the switching frequency is generally in the tens of kHz, transformers, inductors and capacitors can be much smaller, giving high volumetric efficiency.

The advantages of the SMPS are countered by the potential for electromagnetic interference (EMI). This is due to the switching transients and can be ameliorated by careful component selection, layout and shielding.

Is the shielding similar to the copper/zinc mesh  that I have seen?

I am reading Understanding Basic Electronics by Larry Wolfgang and one chapter mentioned EMI.

Title: Re: Are those switching transformers
Post by: strawberry on June 05, 2019, 03:00:25 pm

Quote from: fixit7 on June 05, 2019, 12:59:45 pm

Is the shielding similar to the copper/zinc mesh  that I have seen?

if wire is surrounded by copper mesh, it becomes shielded wire or cable.
transformers are shielded with copper tape or steel cage/box to reflect and absorb radioation, most of it
you can shield sensitive components from noise or the noise source or both