I wish to build a little decent power supply for my IoT devices, would like also to implement more protection from the live 230V AC side and I decided to put a fast blow glass fuse in a nice holder, thermal fuse SF70E and a varistor for HLK-PM01 AC-DC 5v/600mA Converter module.

Now the questions are:

I found example regarding the varistor value 10D561K, and I don't understand why it's not like 10D241K or 10D271K (this is what I have at home)?

enter image description here

I would make it like this: enter image description here

Also for the max. 600mA load on the DC side, what fast blow fuse value should I use on the live 230 AC side 200mA, 500mA, 750mA or 1000mA?

  • \$\begingroup\$ You may want to compute Vpeak and learn about 3kV transient test and HiPot test compliance for common mode. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jul 9 '18 at 22:07
  • \$\begingroup\$ @TonyEErocketscientist Yeah, but unfortunately I'm not rocket scientist like you! \$\endgroup\$ – beic Jul 9 '18 at 22:15
  • \$\begingroup\$ But you do know how to google it right? This isn’t rocket science. That’s why they use a 560V varistor because Vpp=2x1.414xVac (max). (RMS to Peak to peak) \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jul 9 '18 at 22:24
  • \$\begingroup\$ @TonyEErocketscientist Yes, I read something about peak 2 peak for 230V should be 325,22Vpp, right? \$\endgroup\$ – beic Jul 9 '18 at 22:28
  • \$\begingroup\$ Nope that’s peak not peak tp peak of the sine \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jul 9 '18 at 22:31

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