Fast or slo blo?

[teemuk]

What a coincidence, at the moment I'm dissambling and troubleshooting a Bosch battery charger, which is an SMPS unit. Inside: 15-ohm NTC for inrush limiting and a slo-blo fuse.

[kg]

As much as anything else, it can be a matter of transformer size. All power line transformers have a turn-on surge all by themselves, whether they're loaded or not. The size of the surge depends on the size of the transformer and exactly where in the AC cycle they are turned on compared to where in the AC cycle they ran down to when turned off (that is, the remanent flux in the iron from turn off).

this absolutely happens. i had to take measures to increase the DCR of the main plate transformer winding to limit the turn-on surge. i would blow 15a fast blow fuses with alarming regularity.

steve bench set me straight: Current Inrush with Linear Power Supplies | ken-gilbert.com

Hmmm.... I wonder if it's possible to design a tube specifically for musical amplifier use that is beefed up to withstand the normal (ab)use that musicians do these days, and preserve the internal electron ballistics that account for how the tube sounds.

they already do--it's called the sovtek/reflektor 5881.

[jmaf]

Thanks R.G, Steve Conner.

Line voltage here is 220v, i can imagine then that the current surge in the USA is half at turn-on? Kinda the inverse of continuous use where current would be twice, at the initial transient state the cap is charging with the line voltage so it's half over there, right?

Because I often wonder if these sparks are even legal in the USA / Europe market, the iphone charger, kindle charger, etc, all let out a huge spark when plugged into 220vac over here.