How to measure germanium Hfe TUTORIAL!!! (pcb & spreadsheet)

[Arcane Analog]

Be honest and tell me how many and what kind of germaiun based circuits you have built.

Why would you start with a device that has a lot of leakage or not enough leakage? The result IS pridictable and it makes no sense not to make sure you are using the right tools. It is very apparent that anyone that does not think starting off with a good idea about the transistors they are using do not know much about germanium based circuits. That is like saying getting the proper voltages on your pedal or using established voltages as a reference on a circuit is not important. It makes zero sense.

That's the whole point, getting a "good idea" about the transistors is not getting a grasp of the environment they're used at.

Have you ever watched an unstable transistor in a test circuit? Measure first, then listen. If you do not think measuring devices is a key component you do not have a lot of experience on the subject matter.

yes, but measuring gives you an idea about the range to make it work with, it's not absolute.

I am saying if you are working on a circuit that needs leakage, you have to measure the germanium device to make sure it will work before you audition the device.

Again, this is not about the quality of measurement as it will be not so necessary to determine absolute values as they would change anyhow with two more light bulbs on stage. Go easy, make a range of possible values and deal with it.

[Govmnt_Lacky]

Arcane....

The fact that you have built dozens... hundreds... or thousands of Germanium-based transistor Fuzz circuits gives your points some merit HOWEVER.... they are not absolute.

I say this because the ONLY hard data or "facts" that you can point to is based on how the final product SOUNDED TO YOU! By that basis alone your argument is subjective and not absolute.

Heck... even RG Keen still recommends using your ear as the final decider! and I would doubt it very much if you have more time dedicated to this than he does.

[Arcane Analog]

Arcane....

I say this because the ONLY hard data or "facts" that you can point to is based on how the final product SOUNDED TO YOU! By that basis alone your argument is subjective and not absolute.

Are you reading any of my posts? FORGET SOUND. Just getting some circuits to work - to even get it to pass a signal or sound like crap - revolves around choosing the right device. Some circuits are 100% dependent on leakage to function. So no - you are wrong. I have plenty of hard "facts" that state OBJECTIVELY that transistor selection is essential. There is nothing subjective about making the pedal function. It may not be hard to get a Fuzz Face up and running but there are others that are ten times more difficult.

I have also said that post selection process, it is necessary to test them for sound. You seem to ignore that I have said that in almost every post. Not once did I say you should not listen to the transistor.

It is fine a dandy to type a post saying just use your ears. The reality is that does not always work. I encourage you to go build a MKI. Try it at least once. You will have a new appreciation for germanium transistors after that build.

[deafbutpicky]

If you need to know, I've build several SI and GE FFs and diode related , and am to get a Darlington FF high gain device to work under changing conditions, only problem is a heat fan opposed to it makes it squiggle too much to my likes at now, what about you...

[Arcane Analog]

If you need to know, I've build several SI and GE FFs and diode related , and am to get a Darlington FF high gain device to work under changing conditions, only problem is a heat fan opposed to it makes it squiggle too much to my likes at now, what about you...

Exactly. From your posts it was extremely obvious that you have very little experience with germanium. With all due respect, building a few Fuzz Faces cannot give you a good grasp on the subject. Making a Fuzz Face work and sound good is pretty damn easy.

My experince comes from reality - not supposition.

[deafbutpicky]

Enlighten me/us, your  previous posts didn't..., my experience comes from measuring vs sound and this topic is
about measuring; what do you do to hit the sweet spot within a range? 

[Arcane Analog]

Again, there seems to be confusion about hitting a certain sound or sweet spot. That is not really where I was going per se. Perhaps everyone is still associating the builing a Fuzz Face with building all fuzz circuits.

I have posted examples already. Circuits like the MKI, MKII, MKIII, FZ-1, all need some minimum or specific ranges of leakage and/or HFE to work properly or to not sound like garbage without getting crazy and heavily modifying the circuit. Then again, slapping trimmers on them will only make things worse in some cases. To dial them in or tame them to be useable you need a certain interaction between leakages and HFEs and those interplay with the other transistors. Not so much the MKII but getting a decent MKI that does not craclke and fizzle or have a terrible decay can be insanity. For such simple parts count they can be extremely tough to dial in. If you are going about it blindly without taking measurements and/or transistor type into consideration you will probably drive yourself insane.

I 100% agree that testing them for sound is essential. I happen to believe measuring them beforehand is just as important and it will help in the long run.

[karbomusic]

Again, there seems to be confusion about hitting a certain sound or sweet spot. That is not really where I was going per se. Perhaps everyone is still associating the builing a Fuzz Face with building all fuzz circuits.

I have posted examples already. Circuits like the MKI, MKII, MKIII, FZ-1, all need some minimum or specific ranges of leakage and/or HFE to work properly or to not sound like garbage without getting crazy and heavily modifying the circuit. Then again, slapping trimmers on them will only make things worse in some cases. To dial them in or tame them to be useable you need a certain interaction between leakages and HFEs and those interplay with the other transistors. Not so much the MKII but getting a decent MKI that does not craclke and fizzle or have a terrible decay can be insanity. For such simple parts count they can be extremely tough to dial in. If you are going about it blindly without taking measurements and/or transistor type into consideration you will probably drive yourself insane.

I 100% agree that testing them for sound is essential. I happen to believe measuring them beforehand is just as important and it will help in the long run.

^Emphasis added. I don't think anyone would really disagree with the value you are trying to get across. Where it gets sticky for anyone is when the words "sounds like" show up in an objective description.  

I do understand you are considering the usual expected sound those products were designed to make and within that confine I agree with you. Since much of what makes a guitar sound good from the pedal, to the amp, to the cab, deals with the exploitation of failures and shortcomings, using the word measure and sounds good together can get a bit tricky (as evidenced in this thread) even when you are right.  It's the very reason we see so many people end articles and advice with "use what sounds best to you" because it varies that widely even outside of what you or I might think sounds even remotely functional or completely wrong.

Just think of the great sounds that likely exist for no other reason than as a result of not doing it right; I do get the point you wanted to make though; just adding thoughts we can chew on. Now, allow me to make an offering as well as show that I'm not against measuring. Here is the test circuit I built right after getting my first batch of Ge's. I've got that puppy calibrated to exactly 9V and within 1 ohm  

[Arcane Analog]

A MKI sounds like garbage when you have a howling, crackling, sizling mess with a weak or no guitar signal mixed in.
A MKII sounds like crap when you have 90% hiss and 10% fuzz and you are not entirely sure you can hear any guitar.
A MKIII or FZ-1 sounds like garbage when you have only 2-3 seconds of sputtering sounds and then it gates out completely.

I have already said several times that I am not talking about tuning it to taste or finding a sweet spot. I am talking about getting the pedal to function so you can play your guitar through it and hear your guitar without uncontrolable hiss, gating, etc. If you cannot digest that I cannot help you.

You can try to split hairs and save some face and say well "we might like those sounds." Why don't you try to building one first before providing your opinion. Have you even played or heard any of the circuits? It amazes me that people jump into these threads and offer advice or information without any practical experience to back it up. It provides only misinformation.

Next time you build one of those testers you might want you use aligator clips or spring loaded sockets. As I have pointed out several times those tiny sockets are going to lose tension extremely fast and you will have your transistor flalling out very easily.

[Arcane Analog]

Double post.

[karbomusic]

You can try to split hairs and save some face and say well "we might like those sounds."

It wasn't a save face situation for me, one must be in a "win/lose" mindset for that to even enter their mind which I certainly am not. I offered some additional thoughts, take them, leave them, ignore them as is life. I don't know how much nicer and agreeable I could possibly be so it appears this is not the discussion for me if interpreted as it is above.

Next time you build one of those testers you might want you use aligator clips or spring loaded sockets.

Not really, it works as-is for my needs.

[Arcane Analog]

You can lead a horse to water but you cannot make it drink.

[Govmnt_Lacky]

You can lead a horse to water but you cannot make it drink.

... and sometimes they drink the Kool Aid and don't know any better or are resistant to trying something else! 

This really is going nowhere. Good luck to the OP in his endeavors.

[Arcane Analog]

You can lead a horse to water but you cannot make it drink.

... and sometimes they drink the Kool Aid and don't know any better or are resistant to trying something else!  

This really is going nowhere.

You should take your own advice. I have done everything covered in this thread and on this and other boards extensively if not exhaustively. Have you? Judging by your comments I think not.

I test first, audtion second. Can you trust your ear to find leaky germs?



It will certainly be hard for you to go anywhere with this when you do not read/comprehend what I wrote several times. I still do not think you have grasped the difference between subjective and objective observations.

[Circusbrains]

Fun thread

[lars-musik]

Problem: Touching the transistor under measurement doubles reading

I built the RG Keen tester on perfboard a while ago and was quite unhappy with the voltage measurement dropping for minutes on end. Now I just found the time to have go at a batch of AC128K I bought of ebay in January .

I wonder if somebody experienced that touching the tranny shortly (like a quarter of a second and in a perfectly healthy state, no fever whatsoever) whilst measuring upsets the reading quite strongly. I know that the leakage is heavily temperature dependent. But a squeeze of the solid metal housing (the AC128K are bold square things with a built-on heatsink) shouldn't change the temperature that much that the reading doubles from .654V to about 1.2V within second. Is that possible and if yes would such a transistor be a good friend on a stage?

I just waited about 5 minutes and the reading settles now at around .89V in contrast to .654V previously. Same transistor nothing moved. That is quite unsatisfying. I find myself looking at ebay offers for an Atlas DCA55 whilst waiting for the tranny to calm down. Frowning at the same time at the 24 others in the box waiting to be assessed.

[mac]

Problem: Touching the transistor under measurement doubles reading

Heisenberg Uncertainty Principle, you change what you measure

It's unlikely that in a blink of an eye you can transfer so much energy to double the reading.
But some germs, like 2N1114 have the base connected to the case. Touching it alters the reading. This is no the case.

mac

[lars-musik]

I see.

Maybe that's why you shouldn't built Fuzzfaces and the like if you don't fully understand quantum physics.

What musician wants a Schrödinger's cat-pedal on stage where you can see if it is alive not until you plug it in your amp and stomp the switch? However, I guess I'll just refrain from touching the transistor and see to it that there are none of my probing fingers left in the enclosure when I'll finally box it.

Strange still, though.

[LightSoundGeometry]

Again, there seems to be confusion about hitting a certain sound or sweet spot. That is not really where I was going per se. Perhaps everyone is still associating the builing a Fuzz Face with building all fuzz circuits.

I have posted examples already. Circuits like the MKI, MKII, MKIII, FZ-1, all need some minimum or specific ranges of leakage and/or HFE to work properly or to not sound like garbage without getting crazy and heavily modifying the circuit. Then again, slapping trimmers on them will only make things worse in some cases. To dial them in or tame them to be useable you need a certain interaction between leakages and HFEs and those interplay with the other transistors. Not so much the MKII but getting a decent MKI that does not craclke and fizzle or have a terrible decay can be insanity. For such simple parts count they can be extremely tough to dial in. If you are going about it blindly without taking measurements and/or transistor type into consideration you will probably drive yourself insane.

I 100% agree that testing them for sound is essential. I happen to believe measuring them beforehand is just as important and it will help in the long run.

I am still a huge noob and use a cheap chinese tester but already found out you have to experiment and test for upper and lower limits on transistors for fuzz circuits ..that is what "matching" means I think lol 

[Rob Strand]

RG's article has some good info in it.   

His test circuit is nice and simple and does the job.   If you study how it works you will learn something about transistors as well.

The other good thing is many people use that circuit so when they quote Hfe and leakage (Iceo) everyone is on the same page.