# Help me identify some Ge transistors suitable for Fuzz Face and Tone Benders



## soggybag (Jul 29, 2021)

I have a bag of Ge transistors and one of thos TC1 Multi-testers. I not sure how to look at these numbers.

The TC1 shows: Hfe, Ube, Ic, Iceo, Ices. 

ID    hfe    Ube    Ic    Iceo    Ices        Part#    Type
1    81    98    1.3    0.4    37        AC128/01    PNP
2    52    164    6.8    0.13    15        AC128/02    PNP
3    67    93    1    0.31    32        AC128/03    PNP
4    208    133    2.7    0.55    21        AC128/04    PNP
5    227    132    3.5    1.1    30        AC128/05    PNP
6    64    93    0.93    0.25    31        AC128/06    PNP
7    58    155    6.8    0.29    30        AC128/07    PNP
8    54    151    6.8    0.25    32        AC128/08    PNP

here’s a link to a spreadsheet of the all the devices: https://docs.google.com/spreadsheets/d/10O7FYfs_f0x301CYvcvC7pWFFp8Ld2-e3oANXK-AOtc


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## Big Monk (Jul 29, 2021)

soggybag said:


> I have a bag of Ge transistors and one of thos TC1 Multi-testers. I not sure how to look at these numbers.
> 
> The TC1 shows: Hfe, Ube, Ic, Iceo, Ices.
> 
> ...



Here is my take:





Unfortunately, I don't think you'll get a get a suitable Tonebender AND Fuzz Face set out of these. You could however, get either a Tonebender or Fuzz Face AND a Rangemaster out of that lot.

I can't see #5 being useful for anything. The temperature instability on a unit with leakage that high would be severe.


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## danfrank (Jul 29, 2021)

Too many abbreviations and I'm lazy so I'm not gonna look them up. They key to using germanium in fuzz boxes is hfe, which you have listed and leakage. And, you can't use a simple multimeter to test hfe because leakage really fudges those numbers.
Check out this site, read up, and build one of these handy dandy testers for germanium transistors:



			http://www.geofex.com/article_folders/ffselect.htm
		


Some fuzz boxes need low leakage (fuzz face) while others require a mix of low and moderate/high leakage depending on the circuit. Good luck!

And then there is hfe, which also plays a role...


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## danfrank (Jul 29, 2021)

Ahhh... So, that's what Iceo is... I learned something new today!


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## Big Monk (Jul 29, 2021)

danfrank said:


> Ahhh... So, that's what Iceo is... I learned something new today!



OP is using the same little TC1 tester like I do. Frankly, I'm not overly concerned with exact values. For sorting and in general knowing where the parameters roughly lie, the TC1 is awesome.

I compared it with a breadboard R.G. tester when I got it and it was within enough of a ballpark that I didn.t need to look elsewhere or care all that much moving forward.


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## danfrank (Jul 29, 2021)

I'm not familiar with the TC-1 but yeah it looks more than adequate for the job. 
And you post was much more helpful than mine... Sometimes I can come off as a bit snarky, my apologies to the OP.


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## soggybag (Jul 29, 2021)

Big Monk said:


> Here is my take:
> 
> View attachment 14221
> 
> ...


Thanks for the reply. I have about 60 transistor, there’s a link to a spreadsheet, I just copied the first 8 here.

Give me some ideas I can use to sort these out. I’m looking for hfe of 50+ maybe 80+ for Q2 or Q3 and leakage under 300?

And just for clarity Iceo is the leakage? What about those other numbers do they matter here?

Yeah, TC1 is great, it cost me $17 on eBay. Well worth it. It will tell you what type and what the pins are for transistors and diodes, it measures resistors and caps also.


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## peccary (Jul 29, 2021)

This thread from @thewintersoldier shows the leakage and gain he used in each iteration of the FF. He's also done his homework so I'd recommend cheating off his paper.


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## Big Monk (Jul 29, 2021)

@soggybag

Your AC176s have a few units that could be good for a Tonebender.


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## Coda (Jul 29, 2021)

I’m not sure about anybody else, but I have build Fuzz Face’s with transistors that are closer than you would see recommended. I have had good success with, say, Q1 @ 61, and Q2 @ 73. I’m not sure of the leakage, however. I would recommend building the circuits with sockets, and swapping stuff out till it sounds good.


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## soggybag (Jul 29, 2021)

Just to clarify. When using the TC1 the leakage value to be concerned about is the Ices number? And we can just read the raw value?


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## Big Monk (Jul 29, 2021)

soggybag said:


> Just to clarify. When using the TC1 the leakage value to be concerned about is the Ices number? And we can just read the raw value?



Iceo is leakage.


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## soggybag (Jul 29, 2021)

Big Monk said:


> Iceo is leakage.


Thanks! So it’s Iceo * 1000 and we want numbers under 500, under 300 if possible.


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## Big Monk (Jul 29, 2021)

soggybag said:


> Thanks! So it’s Iceo * 1000 and we want numbers under 500, under 300 if possible.



Like @thewintersoldier said, there are no hard and fast rules, however desirable we might find them.

My biggest concern lies not in the biasing of leaky transistors, as we can manipulate the circuit to hit the values we want. My concern with leaky transistors is IF they will stay biased that way, i.e. higher leakage means much greater susceptibility to temperature induced shifting of bias voltage.

Where germanium is concerned, I only use low leakage, vintage NPNs. I want to be able to use a normal power supply and I want temperature induced shifts to be so minimal that it’s not a concern.

I just unloaded about 10 OC75s because, no matter how much I liked the idea of using them, I did not want to deal with the BS associated with them drifting in circuit.


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## soggybag (Jul 29, 2021)

thewintersoldier said:


> Just remember there are general guidelines but no hard and fast rules. Gain of each transistor is subjective as vintage units were all over the place, let your ears guide you there. I try to get in the ball park of gain and leakage for each position of a certain circuit. Tweak resistors connected to each transistor as needed. It's part art form part science. This is why people like silicon fuzz lol plug and play


@thewintersoldier thanks for the reply, your Builds look amazing, very inspiring! I know what you’re saying, its about what youre hearing more than the numbers. I’m just trying to sort and identify some good candidates For a couple builds.


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## Big Monk (Jul 29, 2021)

thewintersoldier said:


> germanium will really only be a problem at high temps. In a house or studio it's pretty stable. Put it on a stage with hot lights shining on it or an outdoor gig on a hot day roasting in the sun its an issue. You can always have external bias to compensate for these issues. Silicon trannies were made because germanium by very nature isnt stable or consistent. then again nothing sounds like it either. If your plying at home I wouldnt worry about it at all. And with charge pump inverters you never have to worry about power restrictions.



I ditched the OC75s and all other leaky devices I owned because I could literally watch on the meter as the voltage rose from normal playing in my guitar room.


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## Big Monk (Jul 29, 2021)

thewintersoldier said:


> that is normal, if you have the multimeter cooked up the the collector on a tonebender the voltage will change when you play, and as the note decays it goes back again.



No, I meant the bias point drifted. Noticeably.

Not a huge issue with Fuzz Faces but the Tonebender starts to gate annoyingly if the voltage creeps too much.

I personally like the General Electric 2N169 NPN. They are my favorite and rarely exceed 40 microamps leakage.


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## Big Monk (Jul 29, 2021)

thewintersoldier said:


> build a scarab deluxe, youll love it, and a fuzz face with bc183s and you might leave germanium behind forever!



I love Silicon Tonebenders but prefer Germanium. The General Electrics are incredible.


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## soggybag (Jul 29, 2021)

thewintersoldier said:


> if you want you can send me the values for gain and leakage and I can give you an idea what you could do with them. And thanks for the kind words, I simply echo the things I've learned from those nice enough to help me.


Well, that’s a very generous offer, and I have a spreadsheet with all of the values! I used the TC1 Multi Tester.









						Transistors
					

Sheet1  ID,hfe,Ube,Ic,Iceo µA,Ices µA,Part#,Type,Pairing 1,69,167,6.8,150,12,AC128/01,PNP,Q1,-,Tone Bender 2,50,179,6.9,65,7,AC128/01,PNP,-,60/60/100 3,64,168,6.8,120,10,AC128/01,PNP,- 4,192,140,2.3,240,11,AC128/01,PNP,Q2,TB? 5,17,126,1.9,330,14,AC128/01,PNP,Q3?,TB? 6,64,169,6.8,88,10,AC128/01,PNP,-




					docs.google.com
				




(let Me know if there is a sharing issue, it Should be set to view)

I have about 50 PNP, and about 20 NPNs. I had the idea to do some positive ground and negative ground pedals. Currently I have 3 Fuzz Factories and 4 Tone Benders on on bench in progress. I’d like to make a couple Fuzz Faces style pedals.


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## soggybag (Jul 29, 2021)

thewintersoldier said:


> iceo is leakage correct? and that value is in mA I'm assuming. I'm I right? I used the geofx tester for years and now a dca55 so I just need to verify and I can start working it out. fuzz face and tonebender mk1.5 will be easy cause they basically use the same values for transistors. What tonebender circuits are you looking to build?


Thanks for the help! Iceo is the leakage. The tester sometimes reads this as 77uA and other times it reads as something like m, or mA. Yesterday I measured everything and the numbers were always a decimal today they seem to be measuring in integers.


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