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if you read just a few posts up, people are mentioning using transistors with 500ua leakage in certain circuits with no problem. i've used the 404's in a buzzaround with good results.

robinbowes wrote:I just received a batch of GT404G (NPN) and GT402G (PNP) germanium trannys from Russia.

I've tested half the 404s with my DCA55 with the following results (Hfe + Leakage current):

105 / 5.22 mA
115 / 0.64 mA
110 / 0.51 mA
127 / 0.90 mA
106 / 0.79 mA
103 / 0.55 mA
160 / 1.07 mA
127 / 0.73 mA
115 / 1.13 mA
84 / 0.81 mA

I measured a couple of the 402s and got this:

116 / 0.19 mA
139 / 0.17mA

RG says "100uA is common, 200 happens pretty often. More than 300uA means the device is suspicious, and more than 500uA I would say is bad." [1]

So, based on that, all the NPNs I've tested are "bad" and the PNPs are good.

Is that a reasonable interpretation of these measurements?

R.

[1] http://www.geofex.com/Article_Folders/ffselect.htm

yeah, pretty much...for fuzzes that need low leakage, I usually don't use anything higher than .25mA measured by the DCA55. when you hit .4, .5, .6, etc...that's getting up there.

tho, of course, those can be used for fuzzes that DO need leaky transistors. so, they won't go to waste.

RnFR wrote:if you read just a few posts up, people are mentioning using transistors with 500ua leakage in certain circuits with no problem. i've used the 404's in a buzzaround with good results.

for Q3? since Q1/2 are darlington, they prob should be low leak.

Thanks guys. I'll bear that in mind.

So, anyone want any reasonably high-gain 404s with highish leakage?

R.

Not all fuzzes require low leakage. Check out the article on the Small Bear site about building the Maestro Fuzz Tone. Also Tone Bender MKII do well with highish leakage on Q1.

BTW I had similar experiences with GT404's being leaky. Not as leaky as yours but the leakiest of all Russian germaniums I have, which are usually very low. I found them to be noisy in some circuits but sound killer in a Fuzz Face.

I'm aslo a victim of "Gordelux" ebay seller ( here for the others ) I've got a batch of low 30hfe GT308B germanimun transistors (the ebay page said 80/120 hfe ) .

Some people found a way to use them ?

devastator wrote:I'm aslo a victim of "Gordelux" ebay seller ( here for the others ) I've got a batch of low 30hfe GT308B germanimun transistors (the ebay page said 80/120 hfe ) .

Some people found a way to use them ?

I was considering ordering from him in the past (but didn't), because he made no guarantee...which is reasonable, if true:

"Hello, Sorry, I haven't this statistics.
These parameters from catalogs & datasheets.
I can't check each transistor, because I have them more than 200000 items.
Thanks, Vladimir"

anyway, since they are insanely low leakage (usually), try em in anything that needs darlington (TB MKIII, Park Fuzz Buzzaround, etc)

if you were planning a Fuzz Face...and you can scrape together one in the 50 hfe range, try this...it's pretty loud & brutal:
http://www.luciferstrip.com/fuzz/fuzzfa ... riable.jpg

my final:
http://www.luciferstrip.com/fuzz/fuzzface-fy2-mod2.jpg

...or try 30/30 in there and see what happens..

good luck

Anyone have thoughts on what would be a good price for NOS RCA 2N408's?

Hypothetically speaking, I may know where I can pick up a few hundred and I'd never go through that many myself, I don't think.

Just wondering what folks think

LucifersTrip wrote: I was considering ordering from him in the past (but didn't), because he made no guarantee...which is reasonable, if true:

"Hello, Sorry, I haven't this statistics.
These parameters from catalogs & datasheets.
I can't check each transistor, because I have them more than 200000 items.
Thanks, Vladimir"

anyway, since they are insanely low leakage (usually), try em in anything that needs darlington (TB MKIII, Park Fuzz Buzzaround, etc)

if you were planning a Fuzz Face...and you can scrape together one in the 50 hfe range, try this...it's pretty loud & brutal:
http://www.luciferstrip.com/fuzz/fuzzfa ... riable.jpg

my final:
http://www.luciferstrip.com/fuzz/fuzzface-fy2-mod2.jpg

...or try 30/30 in there and see what happens..

good luck

he may say the truth, when I received the box it wasn't open at all. absolutely new form the russian 80's cabinet I thinks . Just a little disappointed about the really low gain when the page said 80/150Hfe.

I'll breadboard fuzz face/tonbender circuits to start and see if I could do something else with them (original fuzz circuit I hope , a bit tired of fuzz face .... )

devastator wrote:

LucifersTrip wrote: I was considering ordering from him in the past (but didn't), because he made no guarantee...which is reasonable, if true:

"Hello, Sorry, I haven't this statistics.
These parameters from catalogs & datasheets.
I can't check each transistor, because I have them more than 200000 items.
Thanks, Vladimir"

anyway, since they are insanely low leakage (usually), try em in anything that needs darlington (TB MKIII, Park Fuzz Buzzaround, etc)

if you were planning a Fuzz Face...and you can scrape together one in the 50 hfe range, try this...it's pretty loud & brutal:
http://www.luciferstrip.com/fuzz/fuzzfa ... riable.jpg

my final:
http://www.luciferstrip.com/fuzz/fuzzface-fy2-mod2.jpg

...or try 30/30 in there and see what happens..

good luck

he may say the truth, when I received the box it wasn't open at all. absolutely new form the russian 80's cabinet I thinks . Just a little disappointed about the really low gain when the page said 80/150Hfe.

I'll breadboard fuzz face/tonbender circuits to start and see if I could do something else with them (original fuzz circuit I hope , a bit tired of fuzz face .... )

I really think these transistors sound great... I've been through a lot of germanium and this is some of my favorite ever. Definitely give them a listen before you bin them for having such low gains.

Most of my gt/it308b are in the 40-60 hfe range... my testbox uses the rg method.... I've been through about 60 of them... the leakage is insanely low on all of them.

I've built a few fuzz face circuits with these now and they sound great!

My favorites use what read around 40hfe q1 and 50hfe q2 but they sound more like 70-80 hfe to my ears... they bias nice with stock ff values too. Nice big warm fuzz with great guitar volume control play. People that I build for really like them.

Chris Brown wrote:

devastator wrote:

LucifersTrip wrote: I was considering ordering from him in the past (but didn't), because he made no guarantee...which is reasonable, if true:

"Hello, Sorry, I haven't this statistics.
These parameters from catalogs & datasheets.
I can't check each transistor, because I have them more than 200000 items.
Thanks, Vladimir"

anyway, since they are insanely low leakage (usually), try em in anything that needs darlington (TB MKIII, Park Fuzz Buzzaround, etc)

if you were planning a Fuzz Face...and you can scrape together one in the 50 hfe range, try this...it's pretty loud & brutal:
http://www.luciferstrip.com/fuzz/fuzzfa ... riable.jpg

my final:
http://www.luciferstrip.com/fuzz/fuzzface-fy2-mod2.jpg

...or try 30/30 in there and see what happens..

good luck

he may say the truth, when I received the box it wasn't open at all. absolutely new form the russian 80's cabinet I thinks . Just a little disappointed about the really low gain when the page said 80/150Hfe.

I'll breadboard fuzz face/tonbender circuits to start and see if I could do something else with them (original fuzz circuit I hope , a bit tired of fuzz face .... )

I really think these transistors sound great... I've been through a lot of germanium and this is some of my favorite ever. Definitely give them a listen before you bin them for having such low gains.

Most of my gt/it308b are in the 40-60 hfe range... my testbox uses the rg method.... I've been through about 60 of them... the leakage is insanely low on all of them.

I've built a few fuzz face circuits with these now and they sound great!

My favorites use what read around 40hfe q1 and 50hfe q2 but they sound more like 70-80 hfe to my ears... they bias nice with stock ff values too. Nice big warm fuzz with great guitar volume control play. People that I build for really like them.

here's a video of the fuzz I built using 45/55 hfe:

I bought some OC44 Ge Transistors from Pedal Parts Plus recently and I have had good experiences with these in a Fuzz Face circuit, I've got two left and I'm going to use one of them to build a Rangemaster soon....

I'm really having bad times trying to use some really low gain ge transistor, GT308B. they're all around 40 hfe and I still want to use them or at least try to get them working. But I can't find the right biasing process . Is someone able to explain a method to bais properly bipolar transistors ? (in musical circuit point of view)

I know that a bipolar transistor needs a certain amount of current in its base to make a bigger current between collector and emetter (IC=IbXHfe if I'm right) but expect that I'm lost . Especially on chosing the needed current (collector/emetter) and the good values to chose for resistor (impedance issue and stuff).

thanks

devastator wrote:I'm really having bad times trying to use some really low gain ge transistor, GT308B. they're all around 40 hfe and I still want to use them or at least try to get them working. But I can't find the right biasing process . Is someone able to explain a method to bais properly bipolar transistors ? (in musical circuit point of view)

I know that a bipolar transistor needs a certain amount of current in its base to make a bigger current between collector and emetter (IC=IbXHfe if I'm right) but expect that I'm lost . Especially on chosing the needed current (collector/emetter) and the good values to chose for resistor (impedance issue and stuff).

thanks

I've had great results with lower the low gain transistors... try adjusting the 33K to give something like .8V instead of the more common .5V on Q1's collector. Here's one of my builds with transistors in the 40s-50s gain range:

I just recently bought 4X AC127 NPN Germanium Transistors from Pedal Parts Plus, and I'm wondering if all 4 of them are duds, when I check them on my Semiconductor Component Analyzer, it erroneously transposes the emitter and collector leads, I know that the Analyzer is in error because I've compared the pinout it gives me to a diagram I downloaded, my Component Analyzer says that the transistors each have a gain of about ten and leakage currents of about 90uA one minute, and the next the readings are different with one transistor showing about 1.2mA of leakage current, if I put the transistors in a simple 1 transistor amplifier circuit with the emitter as indicated on the Analyzer, I get no signal coming through, so my thoughts are that either all the transistors are duds or they have too low gain and too high leakage to be of any use, I was under the impression that the guys at Pedal Parts Plus go through and pull all the dud transistors....somehow the 4 transistors I got passed through the dud-pulling process.....


Could they also be fake AC127s?....

Hi Dr N

Have you checked that you didn't misread the label and bought geraniums instead ?

Lucifer wrote:Hi Dr N

Have you checked that you didn't misread the label and bought geraniums instead ?

AC127 are germaniums indeed NPN Ge

Hi Sinner,

I put GERANIUMS (which are a kind of flower).

I know AC127s are GerManiums (but thank you for the intended helpful comment). I was just trying to add a bit of mischief. What else would you expect from the Devil ?

Lucifer wrote:What else would you expect from the Devil ?

What else would you expect from the sinner?

Touche !