Toroid for STEPS in the UK?

[peranders]

It depends how satisfied you were with this present version.... maybe it was perfect except for one thing?

 

[skyskraper]

im sure you've got it under the hat already, but can i ask for provision for an input voltage selector switch ? it would be cool for those who move between voltage areas for school or what have you.

i've got a general knowledge question that i've googled and not found a good hit on, but can anyone link me to a site that explains why there is the 220-240 110-120 difference in the world, like the history of it n stuff

 

[peranders]

Sweden had also 110V AC but this was in the 50's I think or maybe in the 40's.

Norway has also the world's most dangerous mains with no neutral!

It cost money to change voltage but it's like when when we in 1967 desided to drive at the right, it costs money. That's the main reason.

 

[steinchen]

What has to happen to make voltage creep over 4mm ? I mean aside of pouring a beer into the psu or taking a shower with it ? If 240V gets on the secondary side, wouldn't it blow the regulator, fuses, electrolytic caps etc ?

I don't want to play down the risk and would appreciate a modification of the pcb. I want to understand why 4mm isn't enough creepage distance.

A decade ago my psu DIY builds without a pcb were much more dangerous, I'm afraid :/

 

[peranders]

I think you are misunderstaning a bit here. It's the potential that is dangerous. The electronic will probably work perfectly but what happens if you touch it?

8 mm is enough if the surface isn't too dirty and not too moisty. This is regarded as "enough".

If you have a "normal" surface and apply 4 kV you may get into trouble with 4 mm or less AND you at the same time are touching something metallic AND you are grounded good like holding in a heat radiator or the sink. There are lot's of conditions at the same time as you see.

In clean dry air it takes 3 kV per mm airgap to get a spark but in surfaces it's not the same thing.

So if the pcb is clean and not located in Borneo it will be pretty safe but not enough safe to meat any electrical approval.

 

[PeterR]

Quote:

Originally Posted by skyskraper im sure you've got it under the hat already, but can i ask for provision for an input voltage selector switch ? it would be cool for those who move between voltage areas for school or what have you.

There already is. Just wire the selector switch to pads A...D instead of using jumpers.

 

[tangent]

Quote:

can i ask for provision for an input voltage selector switch ?

There are power inlet modules (you know, the thing with the IEC jack and the power switch) that have special switches that rearrange what the STEPS calls the A-D wires. Corcom, Qualtek, Schurter, Schaffner...they all make these.