testing Ge-npn's (and pnp's)

[mat]

I know i cannot test germanium npn's with R.G.'s tester (http://www.geofex.com/Article_Folders/fuzzface/fffram.htm) as it is. Could it be modified to be able to test the npn's also ?

Also I would like to make sure I read the DMM in a right way when measuring PNP Ge's.

I put the transistor in and read (battery exactly 9V, multimeter on 20VDC setting) for example 0.30V and that is the leakage and coverted into mA's it would be something like 120mA ? Is this right so far ?

Then I push the button and and the meter reads 0.80V. So I substract 0.30V from 0.80V and get 0.50V and the real gain of the transistor would be 50(hfe) ? Right ? 

Thanks,
mat

[TheBigMan]

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

The last paragraph talks about testing NPNs.

[mat]

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

The last paragraph talks about testing NPNs.

DOH! 

I've read the article about 100 times and did not remember that DOH!

Sorry for being so blind.. gottaget some sleep, Thanks TheBigMan 

What do You think of the PNP measuring of mine (if I may ask) Does it seem to be the right way to measure ?

Big Thanks
mat

[Eirik]

Actually I don't think your'e so blind after all Seems to me the npn-testing isn't mentioned i the Technology of the Fuzz Face article.

It's only in the Picking transistors article RG says anything about it.
I to read the article what seemed to be one million times with no result.
I didn't dare to ask either, because every time someone did they were told to read the Technology of the Fuzz Face article, and I like you, thought I was blind...

Your gain readings seem right to me


Eirik

[mat]

Actually I don't think your'e so blind after all Seems to me the npn-testing isn't mentioned i the Technology of the Fuzz Face article.

It's only in the Picking transistors article RG says anything about it.
I to read the article what seemed to be one million times with no result.
I didn't dare to ask either, because every time someone did they were told to read the Technology of the Fuzz Face article, and I like you, thought I was blind...

Your gain readings seem right to me


Eirik

Hi Eirik,

Yes, You are right considering of the NPN measurement tip !  Thank You also for verifying my PNP measuring method !

Btw. I have bought several russian ge-trannies (about 100) and have been getting superb results with them in FF. I will record some sound samples showing the difference between hi and low gain trannies when I have the time. The low gain trannies have been working also very nicely in FF, only the cleaning of the sound with guitars volume will happend sooner than with hi-gain GE's. I will get back to that.

mat

[bioroids]

This is the article about Ge transistor tester:

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

In the last paragraph it talks about testing NPN's. Its almost the same text that you can read at "the tech of the fuzz face" except for the NPN part. Thats the origin of the confusion I supose.

Luck

Miguel

[bioroids]

Hey what are the russian transistors you got? I got like 120, MP20A, MP35 and MP40A+  and been measuring them all. Most of them are low gain, out of the FF "magic values", some very leaky, and some spot on (not many).

I measured them all and separated them in boxes according to gain and leakage (in fact I ended writing the gain and leakage with a sharpie on their tops - plenty space there). You should do the same

Luck

Miguel

[Eirik]

Btw. I have bought several russian ge-trannies (about 100) and have been getting superb results with them in FF. I will record some sound samples showing the difference between hi and low gain trannies when I have the time. The low gain trannies have been working also very nicely in FF, only the cleaning of the sound with guitars volume will happend sooner than with hi-gain GE's. I will get back to that.

Thats cool! I just bought a batch of russian germs myself I expect them to arrive any day now. They are MP41A's.
I can't wait to try them and hear what they sound like. 
I would love to have some datasheets for russian germanium transistors... written in english of course... or norwegian...

[mat]

Hey what are the russian transistors you got? I got like 120, MP20A, MP35 and MP40A+  and been measuring them all. Most of them are low gain, out of the FF "magic values", some very leaky, and some spot on (not many).

I measured them all and separated them in boxes according to gain and leakage (in fact I ended writing the gain and leakage with a sharpie on their tops - plenty space there). You should do the same

Luck

Miguel

Hi Miguel,

I've bought MP36A (npn), GT313A,B,V (pnp), MP39B (pnp), MP20A (pnp), MP40A (pnp) + i'm waiting a bunch of GT308's that is supposed to be very good transistors for FF. I've bought some AC188 and 2N404's but they are not as 'thick' sounding as the russian Ge's IMO.

I also measured the leakage and gain. There are only few of them leaking so much (out of 100 I think 5 of them had too much leakage). I did write the gains also on them. I tested the AC188 + other Ge's that I bought from musikding with grabbing my fingers around the transistor. The reading on DMM changed very quickly (+ they seem to be lots of leakier than the russian ones). I also touched and pressed the russian Ge's with my fingers but the meter didn't rise or did rise only couple of numbers. I think they are great for FF style projects.

cheers,
mat

[mat]

Btw. I have bought several russian ge-trannies (about 100) and have been getting superb results with them in FF. I will record some sound samples showing the difference between hi and low gain trannies when I have the time. The low gain trannies have been working also very nicely in FF, only the cleaning of the sound with guitars volume will happend sooner than with hi-gain GE's. I will get back to that.

Thats cool! I just bought a batch of russian germs myself I expect them to arrive any day now. They are MP41A's.
I can't wait to try them and hear what they sound like. 
I would love to have some datasheets for russian germanium transistors... written in english of course... or norwegian...

The MP41A seems to be pnp and gain between 50-100. I have listing of some russian ge's (in russian) that tells the name,(pnp-npn),gain and few other things. I could scan it at work if You would like to have a copy of it.

I've built 'testbed for FF' where i can easily change every component quickly + the bias resistors are pots. At least I have had great results with lower gain transistors also, so You should try the low gains too.

mat

[bioroids]

I also measured the leakage and gain. There are only few of them leaking so much (out of 100 I think 5 of them had too much leakage). I did write the gains also on them. I tested the AC188 + other Ge's that I bought from musikding with grabbing my fingers around the transistor. The reading on DMM changed very quickly (+ they seem to be lots of leakier than the russian ones). I also touched and pressed the russian Ge's with my fingers but the meter didn't rise or did rise only couple of numbers. I think they are great for FF style projects.

You should measure with the GEO tester. I did it first with the DMM and the results do vary.
Anyway it seemed to me the russian Ge are a little less heat sensitive.

Remember you can use the out of spec ones as Ge diodes too

Luck

Miguel

[Eirik]

The MP41A seems to be pnp and gain between 50-100. I have listing of some russian ge's (in russian) that tells the name,(pnp-npn),gain and few other things. I could scan it at work if You would like to have a copy of it.

Hey! That would be great!!!

[mat]

I also measured the leakage and gain. There are only few of them leaking so much (out of 100 I think 5 of them had too much leakage). I did write the gains also on them. I tested the AC188 + other Ge's that I bought from musikding with grabbing my fingers around the transistor. The reading on DMM changed very quickly (+ they seem to be lots of leakier than the russian ones). I also touched and pressed the russian Ge's with my fingers but the meter didn't rise or did rise only couple of numbers. I think they are great for FF style projects.

You should measure with the GEO tester. I did it first with the DMM and the results do vary.
Anyway it seemed to me the russian Ge are a little less heat sensitive.

Remember you can use the out of spec ones as Ge diodes too

Luck

Miguel

Surely i tested them with R.G.'s tester (with DMM..).

Yes, i have red about the diode trick, thanks for reminding )

mat

[mat]

The MP41A seems to be pnp and gain between 50-100. I have listing of some russian ge's (in russian) that tells the name,(pnp-npn),gain and few other things. I could scan it at work if You would like to have a copy of it.

Hey! That would be great!!!

check Your mail 

mat

[jpm83]

Can I use in R.G:s transistor tester 2,37k resistor in the place of 2,47k resistor, because I couldn´t find 2,47k resistor anywhere.

Sorry about my English it´s not so good.

[bioroids]

Can I use in R.G:s transistor tester 2,37k resistor in the place of 2,47k resistor, because I couldn´t find 2,47k resistor anywhere.

Sorry about my English it´s not so good.

Yes, you can. The bad thing is you have less acuracy on the obtained value, but I dont think it will vary that much.

Where are you from, by the way? There is people from all over the world here! (I'm from Argentina)

Luck

Miguel

[Eirik]

check Your mail  icon_biggrin

Thanks Matti! 

[jpm83]

Can I use in R.G:s transistor tester 2,37k resistor in the place of 2,47k resistor, because I couldn´t find 2,47k resistor anywhere.

Sorry about my English it´s not so good.

Yes, you can. The bad thing is you have less acuracy on the obtained value, but I dont think it will vary that much.

Where are you from, by the way? There is people from all over the world here! (I'm from Argentina)

Luck

Miguel

Thank´s

I´m from Finland.

[mat]

check Your mail  icon_biggrin

Thanks Matti! 

You are welcome 

[mat]

Can I use in R.G:s transistor tester 2,37k resistor in the place of 2,47k resistor, because I couldn´t find 2,47k resistor anywhere.

Sorry about my English it´s not so good.

Yes, you can. The bad thing is you have less acuracy on the obtained value, but I dont think it will vary that much.

Where are you from, by the way? There is people from all over the world here! (I'm from Argentina)

Luck

Miguel

Thank´s

I´m from Finland.

Well me too  Terve vaan !