Electronics > Beginners

Why 2 transformers? (pic)

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wraper:
Transformers are unlikely to be faulty. And even if transformer is faulty, most likely is was damaged due other components failing. If windings have low resistance, they should be fine.

wraper:

--- Quote from: TrickyNekro on January 14, 2019, 02:45:13 am ---The whole supply doesn´t seem to be mains isolated, just keep that in mind, might give you a tingle :-/O
edit: under fault conditions most probably though...


--- Quote from: wraper on January 14, 2019, 02:34:36 am ---
--- Quote from: ataradov on January 14, 2019, 02:16:03 am ---IC1 takes feedback voltage from the unregulated output through D5 and adjusts switching frequency accordingly.

--- End quote ---
No it does not. TL494 or it's clone is powered though D5. Feedback is taken from resistive divider connected to the output.

--- Quote ---adjusts switching frequency accordingly.
--- End quote ---
PWM duty cycle, not frequency.

--- End quote ---

Could be both, there are high efficiency supplies that do both.

--- End quote ---
Can not. It's TL494. In any case, changing switching frequency by itself barely changes output voltage.

ataradov:
It is isolated. And I did misspeak, it is obviously changing the duty cycle.

wraper:

--- Quote from: ataradov on January 14, 2019, 02:50:11 am ---It is isolated.

--- End quote ---
I'm not sure what you mean by that. TL494 is powered from secondary side through D5. Pin 12 is Vcc.

ataradov:

--- Quote from: wraper on January 14, 2019, 02:58:33 am ---I'm not sure what you mean by that. TL494 is powered from secondary side through D5. Pin 12 is Vcc.

--- End quote ---
That's a comment about TrickyNekro's comment that this power supply is not mains-isolated.

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