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neovibe quicky

Started by Papa_lazerous, January 27, 2009, 12:58:28 AM

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Papa_lazerous

Ok I got my neovibe pretty much ready to fire up.

Just a quick question thats kinda safety related.  With powering this pedal from the mains I want to put a fuse holder on the side of the enclosure, not sure what value to use.  I am running 230V as I am in the UK I am thinking something very very low.  But if anyone can give me a pointer I would really appreciate it.

I have a few other mains powered pedals and I noticed they have no earth....one part of me thinks earthing it is a good idea and another part of me questions this as the signal GND of the effect will be on the chassis too...

I will be posting pics of this build, the enclosure is something very special, its a combination of some extrusion we had at work and some custom machined parts I did in my lunch break ;)

yeeshkul

#1
Quote
Ok I got my neovibe pretty much ready to fire up.

Just a quick question thats kinda safety related.  With powering this pedal from the mains I want to put a fuse holder on the side of the enclosure, not sure what value to use.  I am running 230V as I am in the UK I am thinking something very very low.  But if anyone can give me a pointer I would really appreciate it.

We have 230V as well and i am powering my Neo straight from mains through a power source circuit that is placed in the very same box. I bought a mains socket with attached fuse drawer, but any kind of a fuse holder connected to the primary will do. I've been using 100mA, slow fuse. No fire so far :)


Quote
I have a few other mains powered pedals and I noticed they have no earth....one part of me thinks earthing it is a good idea and another part of me questions this as the signal GND of the effect will be on the chassis too...

Do you mean that you don't use 3 wire cable(with yellow/green safety wire) for straight powering boxes that have a steel enclosure? You'd better do so ...  ;D
The signal ground star(i've got more effects in that box) is connected to the chassis at the same spot as the power source ground, yes. That is what i have done.

R.G.

Can't wait to see the enclosure.

Safety grounding the enclosure is problematic. Yes, it needs done if an AC line cord enters the box and there is accessible (e.g. you can conceivably touch) metal on the box. However, connecting safety ground at the enclosure will give you the same problem with amps as using two amps - hum caused by the two ground points not being exactly the same voltage. For lowest hum, you'd rather let the amp establish the safety ground point. But then there's that safety issue.

My solution to this would be to use a plug-in wall wart to power the vibe. These things are already designed AND TESTED to conform to the safety thinking that lets you run the equipment ungrounded. Their internal construction conforms to the standards. It's much harder if you're concocting your own.

There are various AC power grounding tricks to make a second safety ground work without hum, involving opening the ground just a little bit. They will not pass safety testing. You're on your own in finding and using these.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

yeeshkul

I have no hum issues with my Neo at all .. am i just lucky? There was a big hum problem once when i plugged my amp and Neo to two different mains sockets.

Papa_lazerous

Quote from: R.G. on January 27, 2009, 09:33:04 AM
Can't wait to see the enclosure.

May be another week till I am ready to unveil, although I should take some pics of it now before its all painted so you guys can see.

Quote
Safety grounding the enclosure is problematic. Yes, it needs done if an AC line cord enters the box and there is accessible (e.g. you can conceivably touch) metal on the box. However, connecting safety ground at the enclosure will give you the same problem with amps as using two amps - hum caused by the two ground points not being exactly the same voltage. For lowest hum, you'd rather let the amp establish the safety ground point. But then there's that safety issue.

This was the conflict I was going over in my mind, its needs doing but its not a simple issue. I have a red ross flanger and that only uses 2 core wire....I may trial it with it grounded and see how the hum situation is. the real solution for me would be to isolate the signal ground from the chassis perhaps??

Quote
My solution to this would be to use a plug-in wall wart to power the vibe.

This is by far not an option at this late stage of play I have the xformer already, its a beauty.  also over kill for my requirements but it has 115-0 115-0 primary so a small change around and it can run overseas ;)

R.G.

Quote from: yeeshkul on January 27, 2009, 10:08:20 AM
I have no hum issues with my Neo at all .. am i just lucky? There was a big hum problem once when i plugged my amp and Neo to two different mains sockets.
With both plugged into the same outlet, the hum issue is minimized, and may not even be present. The different outlets is probably worst case, and you may find anything between, depending on what's plugged in besides the amp and vibe.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

yeeshkul

R.G. does this apply for - let's say - the old EH deluxe pedals as well? I mean those with the internal power source ...