Another Fuzz Face Question

[sarakisof]

Hello folks, years of reading, first time posting. Straight to the point: Lets say i want to build a Fuzz Face Germanium box (notice...not "stomp"box) but without the usual 3DPT/stomp switch that all of us have loved . Just a box/simple fuzz effect unit with an ON/OFF switch. I used the common General Guitars old germanium classic schem, so IN/OUT pcb simple goes to IN/OUT jack mono tip and jack sleeves connected together to GND chassis which is +9V.  (GND=+9VBattery/DC  and  "+path"=Battery/DC - GND). Simple mono jacks , no stereo in for ring circuit powering. Signal comes, signal goes and the unit will be activated with a simple on/off switch. And here comes my question: In most common circuits we use to put a power switch to the "+" path right? In this fuzz example (that practically + is - and - is +)  i have to put the switch in the "Battery -" (which is actually my "+ path", the path that is not connected to chassis) or not? Because if i switch the "+9V path" its like i put a switch in the "GND/Chassis" path.
So my question would also be: "why in common circuits generally we switch the + mains instead of the -/chassis gnding?
(of course in breadboard works in both cases, but we are herer to make things better).

And smthng more, i have already built many "normal" stompboxes, but i wasnt start building also those effects like box units,as above, what are your reccomendations/tips etc. on this? I mean all those circuits were probably designed in the beggining, like that maybe. I mean this is the "core/heart the damned circuit", stomps/switches etc are for just activating/bypass and all those things. If i want only to have the pure effect is it OK just to connect IN/OUT (PCB pads) to IN/OUT tips and sleeves to gnd? 
My apologies if this has been discussed in the past but i couldnt find any info.

Any input will be appreciated.

[sarakisof]

This is my PCB Layout for Fuzz Face in Eagle (switch on +9V rail- , the ground/chassis rail) is this OK?

[pinkjimiphoton]

Hello folks, years of reading, first time posting. Straight to the point: Lets say i want to build a Fuzz Face Germanium box (notice...not "stomp"box) but without the usual 3DPT/stomp switch that all of us have loved . Just a box/simple fuzz effect unit with an ON/OFF switch. I used the common General Guitars old germanium classic schem, so IN/OUT pcb simple goes to IN/OUT jack mono tip and jack sleeves connected together to GND chassis which is +9V.  (GND=+9VBattery/DC  and  "+path"=Battery/DC - GND). Simple mono jacks , no stereo in for ring circuit powering. Signal comes, signal goes and the unit will be activated with a simple on/off switch. And here comes my question: In most common circuits we use to put a power switch to the "+" path right?

depends on whether you're turning ac off or on, usually. ac doesn't have positive or negative, which is why ya can put the switch on it to active voltage.

when dealing with dc tho, you generally want to switch "to" ground, and yes, in this case, that would be your + side of your battery.

its STILL ground... the neutral potential on the other end of a positive signal. think of
"ground" as having zero voltage potential, and + or minus being a measurable voltage potential.

so in your case, i'd still reccomend using the input sleeve to turn it off or on, but if ya don't want to do that, you could put your power switch on either side, ground or not, i doubt it will make any diff whatsoever.

In this fuzz example (that practically + is - and - is +)  i have to put the switch in the "Battery -" (which is actually my "+ path", the path that is not connected to chassis) or not? Because if i switch the "+9V path" its like i put a switch in the "GND/Chassis" path.
So my question would also be: "why in common circuits generally we switch the + mains instead of the -/chassis gnding?

well, in this case, "+" is ground, so it needs to connect to the case or the whole thing won't work right.  the 9 volt potential is between + ground and - voltage. its the same as a normal kinda setup, but inverted.

normally we don't switch the + voltage, we switch the connection to ground off and on. in this case, "ground" being + 9v and "positive" being 0 volts, the potential still remains the same... 9 volts. you could think of the 0 volts being -9 volts, and the positive voltage as being zero volts if it makes it easier. the reason ya switch TO "ground" in a dc circuit is also cuz it doesn't create audible artifacts the way + voltage does, and its safer, cuz you're connecting to a neutral "ground" instead of a hot circuit.

i doubt i'm explaining this too well, sorry

like, say ya took two 9 volts, and put them in series. where the + of one batt meets the - of the other one, that could be looked at as +9 volts there... and 18 at the final termination... or you could think of the mid point being "ground"
and one side being negative 9v and the other positive. its still the same voltage, 18, but where ya tap it makes a big diff in how you can apply it. the "positive" in the middle meeting the negative makes for a dandy midpoint.

god. i'm probably making this worse by the letter

(of course in breadboard works in both cases, but we are herer to make things better).

And smthng more, i have already built many "normal" stompboxes, but i wasnt start building also those effects like box units,as above, what are your reccomendations/tips etc. on this? I mean all those circuits were probably designed in the beggining, like that maybe. I mean this is the "core/heart the damned circuit", stomps/switches etc are for just activating/bypass and all those things. If i want only to have the pure effect is it OK just to connect IN/OUT (PCB pads) to IN/OUT tips and sleeves to gnd? 

if you connect tip and sleeve to ground, its gonna short out the circuit. but yeah, you don't have to add switching or jacks or any of that shit. all ya need really is an input, an output, a hot (which could be pos or neg) and ground. they'll work just the same, if i'm understanding your question right.

My apologies if this has been discussed in the past but i couldnt find any info.

Any input will be appreciated.

there is no such thing as a stupid or invalid question,  as ya get more experience with this, you'll find there's ALWAYS something new to discover.
my one bit of advice tho is make your questions a little easier to follow, and you'll likely get better responses.

its easier to say, answer 10 simple questions than one complex question with 10 parts!

anyways, hope that helps a little til someone with a bit of intelligence checks in to help.

new here? welcome to the forum!

[sarakisof]

Thank you pinkjimiphoton for helpful reply and my apologies for long first post. 

if you connect tip and sleeve to ground, its gonna short out the circuit.

obviously yeap, but u are right - its my fault, i wasnt clear enough. i d like to say :  "is it OK just to connect IN/OUT (PCB pads) to IN/OUT tips and then the jack sleeves to gnd?  in/out--->tips  ,  gnd--->sleeves" haha
Understood 100% what you are saying about + 0 - , gnd theory etc, u were perfect. Moreover in old schematics they used to symbolise gnd as "0"
Lesson learned. Switch to GND.

new here? welcome to the forum!

Nice to meet you 

[pinkjimiphoton]

likewise! gonna hit the rack, 2:21 am here and i gotta gig tonite lol peace!

[duck_arse]

can I have a swing? also, welcome to posting.

in a neg ground circuit box, it is generally easier to grab the single V+ wire and put a switch in, rather than lassooing all those ground wires. [all this based on NO footswitch, just an on/off power switch]. and so, if you were going positive ground, it will be easier to grab that single black wire from the batter snap, put the power switch in there, and bob's yer unkle.

[GibsonGM]

So my question would also be: "why in common circuits generally we switch the + mains instead of the -/chassis gnding?

Hi Sarakisof, welcome!   Because you asked specifically the above, and you are talking about "Chassis" and so on.... I will answer based on using MAINS voltage (the kind that can kill you).  This is not relative to stompboxes, but to the sort of items that run on MAINS power.

They put the switch in the 'hot' line with mains because, if you switch the ground to turn on/off a light in your home, for example...the wire to the light will still be hot all the way through the device (the light) even if the switch is set to "off".   By switching the hot, you eliminate long stretches of hot wire that could in theory be dangerous if touched or accessed otherwise.   

Of course, when using low voltage in stompboxes, or circuits running on low voltage, we can use ground switching to achieve a few more "tricks' as mentioned, when using DC, and since this is not dangerous, there is no reason to stop doing so!   But you could not do many of these things using MAINS AC Power.   

[sarakisof]

Thank u all guys you are awesome   

and so, if you were going positive ground, it will be easier to grab that single black wire from the batter snap, put the power switch in there, and bob's yer unkle.

yes thats what i was thinking about...

They put the switch in the 'hot' line with mains because, if you switch the ground to turn on/off a light in your home, for example...the wire to the light will still be hot all the way through the device (the light) even if the switch is set to "off".   By switching the hot, you eliminate long stretches of hot wire that could in theory be dangerous if touched or accessed otherwise.   

Of course, when using low voltage in stompboxes, or circuits running on low voltage, we can use ground switching to achieve a few more "tricks' as mentioned, when using DC, and since this is not dangerous, there is no reason to stop doing so!   But you could not do many of these things using MAINS AC Power.   

Excellent, you were very clear and thats what i was thinking of exactly

the wire to the light will still be hot all the way through the device (the light) even if the switch is set to "off".

Maybe its probably because i have started with tube amplification and there you deal with mains  and then B+ can give you lethal situations 

Anyway, i will go with this (thats also how GeneralGuitar wiring layout uses)

so in your case, i'd still reccomend using the input sleeve to turn it off or on

So, i will use DC power supply and IN Stereo jack.  DC-  -----> PCB- (BAT-/"GND" or whatever)  and  +9VDC ------> IN Ring, so when a MONO jack inserts: Ring/+9V gets connected to IN Sleeve which is connected to +9V circuit rail. So mono jack plays the role of a switch. Couldnt be more specific right ? 

So my PCB will be finally like this, please correct me if i am wrong.
I would also appreciate if you could check my Layout once again for me (one more eye never hurts  ) and tell me if i have missed smtng.

Any input is welcome !

[pinkjimiphoton]

looks good to me! you sure ya wanna go for the 8.2k resistor instead of a trimmer?
it can be a bitch to get q's that will bias easily sometimes.

[sarakisof]

I was thinking of putting female pin heads as a socket so i can swap res's. But i may finally end up with trim's. If u were in front of my screen right now and pressed 3 or 4 Ctl+Z's  you could see that those resistors were trims haha 

@ pinkjimiphoton: As i work together the Demeter Trem amongst others in Eagle these days and i m sure you pinkjimiphoton (or others of course) have already built this, i will be a lil off topic for an instance and ask a question about Demeter : i am (not really) stuck in the Vactrol pins and between those too many schems/corrections/versions u know...  1 image is 1000 words so i attached you a pic showing you the difference between mine and the schem/layout i follow. Notice the pins of VTL5C on PCB layouts. In the schem i follow pins 2,3 goes to "blue rail" , i do the same in mine but as u can see in my PCB my 2,3 are orianted in different way  Its about component's footprint or smthng? (I used VTL5C10 instead ofVTL5C1 but i guess are all the same VTL5C"X"). Confused.
Its seems a bit "bureaucracy"/technic/silly (not real "brain usage" if u know what i mean- i ve understand LED-LDR polarity) but it must be solved in Eagle so to finish the project 

Mine is above and the schem i follow is below the black line. GND rail is "green" highlighted. (ignore draft layout etc, i m in the start of the process).

[pinkjimiphoton]

i'll take a look in the .... err... later, when i get up.

but trust mate, i'm a right @#$%in idiot with this shit 90% of the time, my gig is letting the magick smoke outta things and playing mad scientist and shit.

you need someone thats not a bloody lunatic that actually can answer your question, so i'm gonna likely layout and make some popcorn and see if someone can answer you so maybe i can learn something too

[duck_arse]

sarakisof - in these matters, the DATASHEET is your bible.

testify, brother.

[sarakisof]

sarakisof - in these matters, the DATASHEET is your bible.

testify, brother.

Yeap obviously, i did checked the datasheet first, but the schem found on internet is known of "corrected/100% working) so i was confused (and still be  )

So in this one VTL5C wiring is wrong?  (3,4 pins swapped?)

https://www.flickr.com/photos/58371367@N08/6280395475

Datasheet: http://www.image.micros.com.pl/_dane_techniczne_auto/oovtl5c2.pdf

LDR emitter is PIN 3 and goes to GND in a Trem circuit as i know right? (so the schem from internet is wrong)

[bluebunny]

So in this one VTL5C wiring is wrong?  (3,4 pins swapped?)

Pins 3 and 4 are the LDR (not a phototransistor as in the Flikr picture, btw!).  The LDR isn't polarised, so 3=4 - they're interchangeable.  The LED pins (1 and 2) are important.

[sarakisof]

Thanks bluebunny. I was edit typing this while you were replying

LDR emitter is PIN 3 and goes to GND in a Trem circuit as i know right? (so the schem from internet is wrong)

so i guess emitter=pin3 is not critical. But it goes to gnd right? (the anode- of led goes there obviously too..)

[bluebunny]

In that circuit, one end of the LDR goes to ground.  It doesn't matter which end.  There is no "emitter".

[sarakisof]

OK got it. Thanks bluebunny

It doesn't matter which end

--->

The LDR isn't polarised, so 3=4 - they're interchangeable

There is no "emitter"

---->   

LDR (not a phototransistor as in the Flikr picture, btw!)

[sarakisof]

Thank you all for your valuable and helpful advice, fully appreciated 

I am about to finish them, a quick last question on PCB Layout/GND Plane/Traces Etc...

Just look at the image attached. Which one is better isolation 0.8128 or 1.27? My Route Width is 0.8127. I personally prefer the 1.27 one (bigger distance between gnd and traces) but if you notice there are some "sharp edges", not too "squary/rounded/smoothy (if u know what i mean) areas in the plane ...

Any input is welcome !

[antonis]

Don't worry about "sharp" edges..
(let electrons & holes mind about that..)

About "isolation" between 0.8128 and 1.27, it doesn't matter at audible frequencies..
(makes no difference neither from the parallel routes capacitive reactance point of view nor for "skin" effect of currents flowing..)

Larger routes widths are more convenient for preventing etching flaws..
(but more etching solution costly..) 

[sarakisof]

Thank u antonis

PS. I am also greek