Help with orientation on MP39b and GT308b

[roccster]

Sure would like to verify the orientation on these transistors.

Thanks!

[Thecomedian]

The collector is thicker than the emitter from all the material I have read.

Measure the resistances across C to B and E to B.

https://www.google.com/search?q=collector+side+is+thicker+than+emitter&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb

If you lack a meter that will tell you the orientation and the sandwich type, (pnp-npn) then this will help you get any of em done. Once you have a theory of which legs are what, build a safe low voltage, low current circuit to test one in.

http://www.datasheetarchive.com/dlmain/Datasheets-X/DSA841000-16.pdf
http://www.mikroe.com/old/books/keu/04/4-03.gif

With these two links you will notice the package for mp39b is T05, and the pinout for T05 packages is shown in the gif file. The orientation can be figured from where the leads are in the triangle and the overall lead centering on the can (if the triangle is on the right side when you pick it up or the left determines whether it's "up" or "down").

The resistance method can verify whether the transistors are truly oriented this way for extra protection from headache. The gif also makes it easier to discover the base lead to perform these tests.

When you want to find lead info or anything else for a transistor, web search for transistor "name" datasheet. Browse multiple places that come up if you can't find the info at one place.

[roccster]

Thanks alot m8!

Now you shared some light on those docs. I found the pdf as well but couldn´t make any sense out of it

Cheers!

[DrAlx]

I posted info on the GT308 here...
http://www.diystompboxes.com/smfforum/index.php?topic=108518.msg989605#msg989605

It is a germanium PNP. To work out which of the outer pins is the base, use a diode checker.
The base is the pin that will give you a diode junction with the central C pin.

Note there's a difference between GT308b and GT308B.
The "capital B" is a russian "v" sound.  The "lowercase b with a flat line over the top" is a russian b sound.

If you are planning on using the GT308 in a fuzz, you may be disappointed with the result as I explain in that link.

[roccster]

What a mess! Well I belive the ones I got hold of was most probably russian (so I guess they are GT308B).

[lietuvis]

On GT308 meant to be marking dot where Emitter is, then Collector and then Base. These are low power high frequency transistors for oscillators and switching circuits:



MP39 low power low frequency transistors:

[Thecomedian]

I posted info on the GT308 here...
http://www.diystompboxes.com/smfforum/index.php?topic=108518.msg989605#msg989605

It is a germanium PNP. To work out which of the outer pins is the base, use a diode checker.
The base is the pin that will give you a diode junction with the central C pin.

Note there's a difference between GT308b and GT308B.
The "capital B" is a russian "v" sound.  The "lowercase b with a flat line over the top" is a russian b sound.

If you are planning on using the GT308 in a fuzz, you may be disappointed with the result as I explain in that link.

I believe GT308 are the ones used in Joe Bona's Fuzz face.

[roccster]

When it comes to the sheets, are there a standard when illustrating the pins, seen from above (top) or below (bottom)?

[lietuvis]

For GT308 you refer marking dot, that's your emitter.
For MP37-42 you look at the pin side, middle is always Base, then if you look at the transistor from pin side and keep Base on the left, the top pin will be Collector and the bottom will be Emitter

[italianguy63]

I use these (GT308)'s pretty exclusively.

The small "b" is the B.  Low gain, low noise/leak.  Hfe of around 50-55 is typical.
The big "B" is the V.  Higher gain (still lowish), low noise/leak.  Hfe of around 70-75 is typical.

They actually make nice "mellow/warm" fuzzes.

Lately, I have used some V's in Q1, and some high gain/higher leak in Q2.  (Actually a MP20B for Q2).  It is a very sweet setup.

MC

[roccster]

For GT308 you refer marking dot, that's your emitter.
For MP37-42 you look at the pin side, middle is always Base, then if you look at the transistor from pin side and keep Base on the left, the top pin will be Collector and the bottom will be Emitter

That was right on the money.
I have a Multimeter with HFe test, and as you described worked perfectly. I also mannaged to get the J.B Fuzz Face to work (FINALLY) when hooking up it up with the right trans and polarity.

Thanks alot for all your help (all of you)!

/ Richard

[roccster]

I use these (GT308)'s pretty exclusively.

The small "b" is the B.  Low gain, low noise/leak.  Hfe of around 50-55 is typical.
The big "B" is the V.  Higher gain (still lowish), low noise/leak.  Hfe of around 70-75 is typical.

They actually make nice "mellow/warm" fuzzes.

Lately, I have used some V's in Q1, and some high gain/higher leak in Q2.  (Actually a MP20B for Q2).  It is a very sweet setup.

MC

That sounds right, I have the 308b (with the small b), and they meassured just above 50, however, my MP39b meassures above 70 (70-74).
As soon as you guys helped me get the polarity right everything is comming to life. Just now I got the J.B Fuzz Face to rock, and it sounds really warm and creamy. Can´t wait to run it through the amp (testing through a Pod XT)

[duck_arse]

When it comes to the sheets, are there a standard when illustrating the pins, seen from above (top) or below (bottom)?

I've come to the conclusion that if a transistor is drawn 2D style, looking from the top, the pins are not visible, and the drawing therefore does not have the needed info. if, however, the pins are visible on the drawing, as dots or squares, then we must be looking at the under of the transistor.

the best way to get the pin info across is with the 3D style drawing, with the pins sticking out one side, and the body (showing its flats and rounds) sticking out the other. you can even add the collector dot on the case. you then can't get the directions confused.