DIY 300B - fuses question

[shomescu]

Hello guys!🙂

I am building from scratch a 300B - audio note kit 1. From scratch means I purchase separately PCB's and all the components from various sources. Very enthusiastic about this project despite the fact that I am a mechanical engineer with rather limited electronics knowledge.

I need now to plan for the fuses. Noticed in some step by step instructions from Audio Note kit that main fuse is a 2A slow blow.

Since I am in Europe with 220 V I will plan for a 1 A fuse - please let me know if this sounds right.



I have read all kinds of forum discussions regarding fuses on B+...etc.
Can you please let me know in a simplistic way if I need other fuses and where?

If "B+" is a option please let me know what B+ is. 🙂

Thanks!

 

[MikePP]

If "B+" is a option please let me know what B+ is. 🙂

Thanks!

B+ is the nomenclature for a power supply rail (its origin dates back to valve sets where B+ was actually a battery, hence the B)


You should fuse every rail in your product, from the incoming mains, to the rails on the secondary side of the transformer (i.e. all the B+ rails), you're protecting stuff further upstream from burning up (like wires for instance, transformers or other components)

 

[euro21]

I will plan for a 1 A fuse - please let me know if this sounds right.

No.
At least 1.25A, rather 1.6A slow type.

 

[shomescu]

I read again the kit instructions...they mention 2A fuse and I always assumed the kit is for 110V.

So 1.6A you recommend. OK, thanks euro21

 

[petertub]

I read again the kit instructions...they mention 2A fuse and I always assumed the kit is for 110V.

So 1.6A you recommend. OK, thanks euro21

You can start with 1A and if that won't hold use a slightly larger until

it will not fail. No point in too large fuse.