Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: tubenit on August 26, 2021, 06:24:58 am

Title: Standby switch Q
Post by: tubenit on August 26, 2021, 06:24:58 am

Sluckey helped me on on the Carolina SuperSonic build in understanding the rectifier and the standby switch. It worked quite well!


So now I am on another build and it is requested that this build also have a standby switch.  Can I use type  "A" for the standby switch which is prior to the rectifier  OR should I be using type B after node A on the B+ rail?


With respect, Tubenit

Title: Re: Standby switch Q
Post by: sluckey on August 26, 2021, 07:27:49 am

I would not use either A or B. Drawing A won't work as drawn. Point A should be moved to after the switch in drawing B. Make these simple changes and then use whichever one you want. I'd probably choose drawing A because AC current is easier on the switch contacts than DC current.

Title: Re: Standby switch Q
Post by: tubenit on August 26, 2021, 10:54:59 am

Steve,  I am super grateful for your help!  I can't count how many times I was not understanding something or headed the wrong direction and you've generously gotten me back on course!  THANK you for taking the time to explain and even draw out the schematic!   I will follow your advice on this!


Most appreciative!  With respect, Tubenit

Title: Re: Standby switch Q
Post by: pdf64 on August 26, 2021, 11:30:34 am

FYI international electrical equipment standards mandate that the live feed from the wall outlet / IEC inlet should hit the fuse first, then the switch.
Ideally, live and neutral should be switched.
The live feed should go to the back terminal on the fuseholder, not the side one.

Title: Re: Standby switch Q
Post by: tubenit on August 26, 2021, 01:31:09 pm

Quote

FYI international electrical equipment standards mandate that the live feed from the wall outlet / IEC inlet should hit the fuse first, then the switch.

I did not know that? 

with respect, Tubenit

Title: Re: Standby switch Q
Post by: PRR on August 26, 2021, 05:08:18 pm

Quote from: pdf64 on August 26, 2021, 11:30:34 am

...international electrical equipment standards mandate ...

Tubenit isn't international, he's Carolina or thereabouts. 120V juice and single-pole switching.

I'd think if we are catering to dummies, the switch should be before the fuse, so the fuse holder may be made dead?

I'd ask for a cite of 'standards' but I know I could not afford to see them.

Title: Re: Standby switch Q
Post by: pdf64 on August 26, 2021, 05:32:49 pm

My key concern was that the schematics showed a single pole switch on one side of the mains, a fuse on the other. It seems that if the mains connectors are polarised, it’s best to put the fuse and switch on the live side.
I think I should have left it at that :think1:
I’ll investigate the situation regards the standards.

Title: Re: Standby switch Q
Post by: sluckey on August 26, 2021, 05:56:14 pm

Quote from: pdf64 on August 26, 2021, 05:32:49 pm

I’ll investigate the situation regards the standards.

Please report your findings.

Title: Re: Standby switch Q
Post by: PRR on August 26, 2021, 06:06:50 pm

> the schematics showed a single pole switch on one side of the mains, a fuse on the other.

That's remarkably standard for 1960s USA work. It does not need a wire-nut or other splice (or a DP switch, a many-penny extravagance in US commercial thinking).

An excuse is that it should be incredibly easy to Pull The Plug before putting a sweaty finger on a fuse. If we don't listen, our fault.

Title: Re: Standby switch Q
Post by: pdf64 on August 26, 2021, 06:22:25 pm

Hasn’t North America changed to polarised mains connectors since then though?
That seems a different scenario to it being a coin flip which side is which, as with unpolarised connectors.

Title: Re: Standby switch Q
Post by: PRR on August 27, 2021, 12:02:55 am

> changed to polarised mains

Only nominally.