Hi
I have a question on SMPS feedback circuits and would appreciate a bit of guidance. The circuits I have found are using discrete components and both very similar, however the explanations seem to contradict.
In this blog post (1), the author describes the pulse from the feedback winding causes the FET to switch OFF and hence induce current in the secondary winding. Fair enough I thought.
However in circuit (2), the feedback pulse is described as turning the FET ON harder, and it's voltage developed over the resistor in the source, via an NPN transistor, that switches the gate to ground.
(1) http://martin-jones.com/2014/03/03/denon-dvd-1720-dvd-player-power-supply-schematic-and-repair/
(2) http://homemadecircuitsandschematics.blogspot.co.uk/2014/03/12v-5-amp-transformerless-battery.html
Thanks
Mike
I have a question on SMPS feedback circuits and would appreciate a bit of guidance. The circuits I have found are using discrete components and both very similar, however the explanations seem to contradict.
In this blog post (1), the author describes the pulse from the feedback winding causes the FET to switch OFF and hence induce current in the secondary winding. Fair enough I thought.
However in circuit (2), the feedback pulse is described as turning the FET ON harder, and it's voltage developed over the resistor in the source, via an NPN transistor, that switches the gate to ground.
(1) http://martin-jones.com/2014/03/03/denon-dvd-1720-dvd-player-power-supply-schematic-and-repair/
(2) http://homemadecircuitsandschematics.blogspot.co.uk/2014/03/12v-5-amp-transformerless-battery.html
Thanks
Mike
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