#1
This is not directly about "amp building" but it's something I've thought while building my amp..and I just bought a kit.

Something crossed my mind before I kill myself and blow the amp.

Ok so place yourself..in...Germany...or Portugal or Spain..where the power plugs are Type F socket, therefore unpolarized.

I can plug my cable to the wall.....I can turn it 180º and still plug it to the wall. ...inversing the live and neutral...will the wall sockets handle everything automatically?

The same question applies. If I'm stupid enough to connect it to a un-earthed plug...I can connect it to a Type C socket both ways....
Will the power transformer handle things..."both ways"?

I live in France where the wall sockets are Type E, so I will not have any risk...but I'm Portuguese...and this crossed my mind....

If someone could help me or throw me a bone in google....(I've been in google and wikipedia for 3 hours now)...and most amps designs I've studied have been from UK/US sites were the wall sockets are polarized....
Thanks a lot for any help
#2
you have to have a 3 prong cord.
Jumping on dat gear sig train.
PRS Hollowbody II / BKP Warpigs
Strandberg OS6T / BKP Aftermath
Strandberg OS7 / Lace Poopsticks
Skervesen Raptor 7FF / BKP Warpigs
Skervesen Raptor 6 NTB / BKP Juggernauts
Hapas Sludge 7 FF / Hapas Leviathan
Anderson Baritom / Motorcity Nuke BKP Sinner Anderson H2+
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Blackstar ID:Core Beam
#4
the amp transformer doesn't care which is which as long as it has a third ground prong.
Jumping on dat gear sig train.
PRS Hollowbody II / BKP Warpigs
Strandberg OS6T / BKP Aftermath
Strandberg OS7 / Lace Poopsticks
Skervesen Raptor 7FF / BKP Warpigs
Skervesen Raptor 6 NTB / BKP Juggernauts
Hapas Sludge 7 FF / Hapas Leviathan
Anderson Baritom / Motorcity Nuke BKP Sinner Anderson H2+
Warmoth Baritone / BKP Piledriver
Ibanez Rg2120x / BKP Nailbomb

Blackstar ID:Core Beam
#5
If I'm understanding you right you're saying you can switch the live and neutral lines. Whether or not it hurts your amp your chassis would become live if it did not have chassis grounding. But since it does have chassis grounding it will short the live to the ground and throw a breaker or blow a fuse, hopefully before it hurts a polarity sensitive component like capacitors.
Guitars:
LTD F-50
Yamaha EG-112
'77 Harmony
Roadworn Starcaster
Gretsch G5120

Amps:
Vypyr 15
Epiphone Valve Junior combo
#6
Grungebaby. I also know that .

The thing is..all electrical appliances(computer transformers to washing machines) are plugged in this sockets...and even without ground...it works. It would be a pain in the arse if all around Europe(except UK and France) 50% of the time you connect your appliances...you would need to replace a fuse.

So I've been wondering if these Type F sockets are "smart sockets" that inverse the wires depending on where the live and neutral is needed.
Anyway, thanks to both of you for your answers.
#7
If there isn't adequate grounding options, u just have to resort to a ground switch, which was how all ground schemes were before the 70s I think when it changed in the US? Either that, or u tell the Portuguese government that it's a safety risk and they have to change it.
Call me "Shot".

ShotRod Guitar Works

Custom Hand-wired Amplifiers and Effect Pedals.

Est. 2007


Source to everything I say about Guitars, Pedals, and Amplifiers: I make them.


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#8
Hey Cisthe. Amazing how in Europe we don't die everyday while working with electric appliances. With a 0.5 probability!!
Without wanting to start a war, but you were the one provoking ..check the life expectancy between Portugal and California. Or between the EU and the US. Or...who's electrical system is the most common in the world.

...because, you know, those sockets exist in Spain, Germany, Netherlands(all EU but UK, Ireland, France and Belgium). And the Schuko sockets are grounded. But you also have Europlug which there is no ground.

So I've asked around...at the laboratory I work and I think the answer is..
Alternate current. Basically if you inverse them there is no difference when it comes out of the transformer. The difference of potential varies and it always peeks from +220V to -220V anyways...so the theoretical 0V(neutral) will just be in an inversed phase.

So one other question pops. I shouldn't wire the Neutral to the chassis like this?!?!
#9
Huh? Sorry I wasn't trying to provoke anything with the last sentence, it was a joke.


AC (alternating current) really has no polarity. There's phase, but it's not an issue for the most part. If you connect the live with ground or the live with neutral, u'll trigger a few circuit breakers. If you wire the live to the chassis and the chassis doesn't make contact with neutral or earth, then it won't trip a circuit breaker. You'd just get shocked if you touch the chassis while touching another amp chassis/microphone that's connected to neutral. That's why ground switches and two prong cords were somewhat banned. This is what happened.

You still see two prong cords in the US yes. That's only with appliances with insulated metal chassis, or plastic appliances, like coffee makers and vacuum cleaners. It doesn't matter if a "chassis" was live. The consumer will never come in contact with it.


Amplifiers want a metal chassis to avoid radio and other interference. Chassis must be grounded properly.

To answer your question, if the power cord you have does not have a correct way to be plugged in, you don't want to wire anything to the chassis... It's too dangerous. U'd rather have the chassis lifted than live. Ground switches can work. But for the record, it's banned in America.
Call me "Shot".

ShotRod Guitar Works

Custom Hand-wired Amplifiers and Effect Pedals.

Est. 2007


Source to everything I say about Guitars, Pedals, and Amplifiers: I make them.


UG's Best DIY PedalBoard
#10
Quote by ECistheBest
Huh? Sorry I wasn't trying to provoke anything with the last sentence, it was a joke.

Okidoki. Ruff day for me .
Thanks for the answer btw.

Quote by ECistheBest

AC (alternating current) really has no polarity. There's phase, but it's not an issue for the most part. If you connect the live with ground or the live with neutral, u'll trigger a few circuit breakers. If you wire the live to the chassis and the chassis doesn't make contact with neutral or earth, then it won't trip a circuit breaker. You'd just get shocked if you touch the chassis while touching another amp chassis/microphone that's connected to neutral. That's why ground switches and two prong cords were somewhat banned. This is what happened.

You still see two prong cords in the US yes. That's only with appliances with insulated metal chassis, or plastic appliances, like coffee makers and vacuum cleaners. It doesn't matter if a "chassis" was live. The consumer will never come in contact with it.


Amplifiers want a metal chassis to avoid radio and other interference. Chassis must be grounded properly.

To answer your question, if the power cord you have does not have a correct way to be plugged in, you don't want to wire anything to the chassis... It's too dangerous. U'd rather have the chassis lifted than live. Ground switches can work. But for the record, it's banned in America.

So the amp would work with no problem then since the power coming out of the transformer will be corrected by the...rectifier and B+ will be in B+.(not talking about safety at this time).


But again I put the question. I have a tube amp (bought) with metal casing. And in all Europe you can switch the live<->neutral every time and I've never blown a fuse therefore the question is...why?

And ..follow-up:
if you connect the ground pin to the chassis. and you don't connect the "neutral" to the chassis but only to the transformer they should be connected in the house Neutral+Earth connection right?

And...why to we never connect the neutral to earth BEFORE the power transformer(is this what I'm not understanding????).
#11
Ok. First question. The B+ is always higher than the common ground inside the amp, because of the diode. They make sure everything coming through is a positive voltage basically. The sine wave voltage exits the transformer, it is a sine wave centered at 0v, or where ever the voltage of the center tap is at. It can also be floating as well. The wave hits the rectifier diodes that makes sure you only get positive swings. The diodes are given a reference (ground) that makes sure the voltage only swings positive. If the wave is swinging negative at a given time, a rectifier converts it into positive voltage. A filter cap will smooth the spikes and give the amp a healthy direct current (not a wave anymore) voltage for the B+.

There isn't a switch to choose between live/neutral right? My guess is, either the chassis is insulated, or the chassis is floating, or they do some other magic inside. Your question is, why the fuse doesn't blow. Well a fuse blows when too much current flows through it. A fuse is commonly placed between the live input and one of the transformer primaries. The transformer taps are not a short as far as AC is concerned. So you're not shorting anything. Fuse would blow if the transformer was faulty and the primaries ARE a short, even for AC, then the fuse will blow. But you probably won't encounter that.

About the neutral ground thing... Yes, if there is a ground pin, you ground that and keep the neutral floating. I'm not very knowledgeable with house wiring (YET) but neutral isn't connected to the chassis. They only go to the power transformer primary.

Last question, I think it's because neutral is indeed neutral, but it's not ground. If the neutral and ground are connected, and if you reverse the power plug? If the neutral is floating, then there's no fear connecting the live and neutral backwards. Theyre isolated from ground, so the power transformer still functions.


And I think because of the construction of transformers, improper grounding is noisy.
Call me "Shot".

ShotRod Guitar Works

Custom Hand-wired Amplifiers and Effect Pedals.

Est. 2007


Source to everything I say about Guitars, Pedals, and Amplifiers: I make them.


UG's Best DIY PedalBoard
#12
Quote by ECistheBest
Ok. First question. The B+ is always higher than the common ground inside the amp, because of the diode. They make sure everything coming through is a positive voltage basically. The sine wave voltage exits the transformer, it is a sine wave centered at 0v, or where ever the voltage of the center tap is at. It can also be floating as well. The wave hits the rectifier diodes that makes sure you only get positive swings. The diodes are given a reference (ground) that makes sure the voltage only swings positive. If the wave is swinging negative at a given time, a rectifier converts it into positive voltage. A filter cap will smooth the spikes and give the amp a healthy direct current (not a wave anymore) voltage for the B+.

okidoki. Meaning that if I switch ground and live at the primaries of the transformer. The B+ will be at the right place?

Quote by ECistheBest

There isn't a switch to choose between live/neutral right?

Nup

Quote by ECistheBest

My guess is, either the chassis is insulated, or the chassis is floating, or they do some other magic inside. Your question is, why the fuse doesn't blow. Well a fuse blows when too much current flows through it. A fuse is commonly placed between the live input and one of the transformer primaries. The transformer taps are not a short as far as AC is concerned. So you're not shorting anything. Fuse would blow if the transformer was faulty and the primaries ARE a short, even for AC, then the fuse will blow. But you probably won't encounter that.

Concerning the live<-> neutral possible switching I should probably put a fuse in the "neutral" wire as well I guess

Quote by ECistheBest

About the neutral ground thing... Yes, if there is a ground pin, you ground that and keep the neutral floating. I'm not very knowledgeable with house wiring (YET) but neutral isn't connected to the chassis. They only go to the power transformer primary.

Last question, I think it's because neutral is indeed neutral, but it's not ground. If the neutral and ground are connected, and if you reverse the power plug? If the neutral is floating, then there's no fear connecting the live and neutral backwards. Theyre isolated from ground, so the power transformer still functions.



I think this was my biggest conceptual mistake. Confusing "neutral from the wall", with the wires in the DC circuit that connect to the chassis.
The neutral never conducts with ground(except at the house electrical system which is not important in this case) BEFORE the transformer, and BEFORE the AC->DC rectification(right????).

http://www.ampmaker.com/images/ak01kit/ak01sc2.jpg
Therefore, in a schematic like this one. Taking the example from C11 connected to ground, this ground is the same as the "earth" connection to the wall socket (If I understood right, since both are connected to the chassis). It's already DC, meaning that the "bottom" part of the schematic is always at 0V comparing to ground??


Quote by ECistheBest

And I think because of the construction of transformers, improper grounding is noisy.

Stupid EM fields

And again thank you for the patience. I'm a curious person.

And btw. Portuguese authorities are security freaks, believe me if they would come to France, half of the business would have to close for safety issues.