Fuzz face incorrect hfe bias mod question

[PRR]

> have to have a voltage and a not voltage, don't you?

What is a "not voltage"?

Voltage is always RELATIVE.

Any two points.

To have a "not voltage" you need a point defined to be "not".

Yes, being earth-bound creatures and the Earth being so big it absorbs our puny currents with little change, we DO tend to compare all voltages to Earth.

But that's small-minded.

Due to Solar Wind, there is a voltage difference between Mars and Jupiter. Get some long-long meter leads and measure it. Does voltage of the third rock from the sun enter into this?

[pinkjimiphoton]

point noted, paul.

i mean voltage/not voltage as the difference between the presence of voltage and zero voltage (which i'd assume is ground). voltage could be at a postive or negative potential, but isn't zero volts always "ground" for all practical purposes?

i mean, at a 0-0 potential, is current going to flow? i would think not, as there'd need to be a postive or negative difference from 0 to have current flow, right?

sorry to hijack this... trying to learn some stuff i'm obviously not "getting".

so... voltage (i know the nomenclature sucked i used) would be something above or below zero volts or "ground" or "not voltage"... if nothing flows, it can't be voltage, can it?

was trying to way over simplify.  mah bad

[dwmorrin]

point noted, paul.

i mean, at a 0-0 potential, is current going to flow?

Yes.  If you measure the + side of a battery and the V+ wire pad of the circuit board, the voltage is near zero, but obviously a current is present.  Same goes for ground.  Hence why you can get "ground loops."

so... voltage (i know the nomenclature sucked i used) would be something above or below zero volts or "ground" or "not voltage"... if nothing flows, it can't be voltage, can it?

was trying to way over simplify.  mah bad

Take a 9V battery unconnected, just sitting on your bench.  Is there not 9V between the two terminals?  Nothing is flowing, yet the voltage exists.
Voltage is also know as "potential", as in, "current could potentially happen if I connect these two terminals."

[pinkjimiphoton]

point noted, paul.

i mean, at a 0-0 potential, is current going to flow?

Yes.  If you measure the + side of a battery and the V+ wire pad of the circuit board, the voltage is near zero, but obviously a current is present.  Same goes for ground.  Hence why you can get "ground loops."

i totally disagree. in order for there to be current flow, there needs to be a "ground". no ground= no circuit. it has to flow somewhere, in a case such as that you can't possibly have electron flow, as it's an open circuit. the fact that it's connected to ground somewhere on the circuit board would be the only way electrons can flow.

so... voltage (i know the nomenclature sucked i used) would be something above or below zero volts or "ground" or "not voltage"... if nothing flows, it can't be voltage, can it?

was trying to way over simplify.   mah bad

Take a 9V battery unconnected, just sitting on your bench.  Is there not 9V between the two terminals?  Nothing is flowing, yet the voltage exists.
Voltage is also know as "potential", as in, "current could potentially happen if I connect these two terminals."

the voltage may exist, stored, but there is no flow or "current" until both sides of the battery are connected. it's just not possible. in a battery, over time, it may break down somewhat, but when dealing with basic physical properties of matter there's no "electricity" without a "circuit"... there may be electrons, but there's no current or voltage.

when you test a 9v battery, if you touch only the + terminal, you will get no reading. you will only get a reading of the stored voltage by touching it to the negative terminal. other wise you have an open circuit, no current flow possible.

not to be a dick, but in this case i'm right.  like you said, there's "potential"... but that doesn't count until hooked into a circuit.
if there's no load, and connected, you get a short circuit. if there is a load somewhere, you have a circuit.

no connection between -/+?  no circuit, no electron flow possible. no ground/zero volts? whether positive or negative voltage is in the equation, no circuit.

peace

[dwmorrin]

Jimi, you misunderstood me.  In the first example, I meant a working, flowing, power supply with a load circuit.
In the second example it was just a battery disconnected.

[pinkjimiphoton]

gotcha dave, no worries, sorry for the misunderstanding man!

it's all good. 

[polifemo]

in a grounded emitter, it's a short circuit to ground that for all intents autobiases the transistor for ya, similar to a cathode biased tube circuit (while being completely different for reasons i'm not gonna get into here). then all ya gotta worry about is feeding input into the base, and taking the output from the collector.

any time you have the gain maxed out, you're gonna find noise, and a lot of it in some cases.

if you stick a resistor between e and ground, you float the transistor...it has a resistance to ground that helps to turn it down a little.

in a tube amp, you may see a 1.5-3.3k cathode resistor, that's bypassed with a big ass cap, usually around 22u or so... this helps stabilize the tube, helps determine the overall gain the tube is capable of, and the cap allows some feedback and strengthens the tone, lets some high end bleed thru

in a transistor in a grounded emitter circuit, what i've found is that a VERY small resistance (10 - 100 ohms max) between the emitter and ground seems to make the fuzzes more stable, less prone to rfi and hash noise....at the expense of a tiny amount of the overall gain at hand.  so...

some peeps put a 1k resistor in there.. to me, it's too much, mellows out the fuzz, some folks may like it.

so about 47r is a good spot where it knocks back the gain just a little but is still close enough to a short for all intents and purposes for the transistor to function well.
you usually won't even have to tune your collector resistors.

i know this is wrong from an EE standpoint, i'm just trying to explain what i've learned in practical experience smokin' pots and caps and pots and ics and tubes and pots and... pot 

now i know me saying SHORT may be wrong too, but old mr. k in high school, who told us all we were nothing but a bunch of f'n peckerheads always called any connection to ground a "short". 

i mean.. a short is the shortest path to ground, right?

anyways... try the resistor trick. i sometimes use 10r ones. it's noticeable mostly on a wart... just a little less crackle fizz noise... and no cabs

Is this just for Q2 (in a FF) or both trannies?

What about 2xtransistor circuits like TonebenderI/ TonebenderII/ TonebenderIII?

I've tried a small resistor on Q2 in a FF and I do agree that 47R is enough and that actually 10R does quite a lot!

[pinkjimiphoton]

you can do it in pretty much any fuzz circuit. it's cheating, but it works.

if you use a bigger resistor, try to bypass it with a big freakin' cap. but 10r (which i often use, too) to 100r, don't even worry about it. there is a little less gain available but it can really help
with noise a bit.

a small resistor inline with the b+ supply (be it positive or negative, not ground i mean) can also help.

stubborn cases put one in line with the signal from the guitar...up to maybe 10k, but at that point it will noticeably change the tone some.

if you use trimmers on the collector resistors, it also can help... particularly with hissy transistors, often they have sweet spots either before or after the hiss is objectionable
but where you'll still get a decent fuzz. leaky germaniums with a low effective hfe can be tamed somewhat like this.

three stages of low gain ge sound pretty freekin' sweet if it's not too hissy.