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transients in capacitor droppers

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LaserTazerPhaser:
Is there a simple method to mitigate high frequency transients from conducting large currents?

The series current liming capacitor droppers only work when frequency is low, but capacitors are short circuit high frequency. The load on the fullwave rectified side is reactive and can vary impedance rapidly.

Zero999:
There should be a low value series resistor to limit the turn-on transient, when power is applied at 90ยบ, when the voltage is highest, otherwise the fuse will blow and quite likely the rectifier too.

To answer the question: no, a capacitive dropper will always pass higher frequencies, more than lower ones. Swapping the capacitor with an inductor will block high frequency transients, but it will probably work out just as bulky and expensive as a transformer.

Gyro:
Yes, a series resistor, and a protective clamp zener across the load. I wouldn't implement a capacitive dropper without them.

Many commercial applications use a fusible resistor in that position.

LaserTazerPhaser:
What frequencies are typical residential transients?

Nearly any inductance will attenuate high frequency but that would open a window to a resonant LC band in which the fuse would blow if the LC frequency is a typical mains noise frequency.

Maybe residential high frequency transients are all manifest as high voltage transients in which case the MOV should remove them.

StillTrying:
We had a similar thread on this trying to protect LEDs from the switch on and and other transients.

https://www.eevblog.com/forum/beginners/transformerless-power-supplies-circuit-cheatsheet-and-questions/msg2186906/#msg2186906

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