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Toshiba Germanium Transistors: Suitable for fuzz pedals?

Started by Matness, March 31, 2023, 03:44:24 AM

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Matness

Hello forum,

I have a handful of Germanium transistors harvested from a 1960s reel-to-reel machine.
Which if any of these might be suitable for building a fuzz pedal? (see photo)

2x     2SB54
2x     2SB415
4x     2SB440
2x     2SB439

Any circuit recommendations or general tips?
I have some electronics experience but am new to building pedals.

Thanks in advance!

derevaun

If you google "2SB54 transistor" you usually get a datasheet link pretty high in the results. Forward current transfer ratio, or gain, is the main thing to find out. All of those are germanium PNP transistors and the datasheets say their gain is 70+. If that turns out to be the case, and their leakage is reasonable, they're in the zone for several fuzz and boost circuits. IMHO the specific part number matters a lot less than the gain and just the individual quirks of the actual transistor in your hand.

You can test their gain and leakage with this method: http://www.geofex.com/article_folders/ffselect.htm

That method needs a specific and precise resistor, so a dedicated tester may be a more appealing route. A lot of people use a component tester like the TC1, which is cheap, or a Peak Atlas model, which is robust and reliable.

So yeah, those have a good chance of being useful, even highly desirable, for fuzz circuits. Build docs for fuzz pedals will suggest gain ranges and gain ratios between transistors.

Matness

Quote from: derevaun on March 31, 2023, 06:13:17 AM
Forward current transfer ratio, or gain, is the main thing to find out. All of those are germanium PNP transistors and the datasheets say their gain is 70+. If that turns out to be the case, and their leakage is reasonable, they're in the zone for several fuzz and boost circuits.

Thanks derevaun!  I will pick up a TC1 at the earliest opportunity.  Very useful tool!
I realize it is less accurate for testing germanium than the method in the link you gave, so I will keep in mind what I've learned from that page too.

Sounds like these might just be perfect for building a Fuzz Face, and then I'll just need to find an additional NPN for building a Jordan Boss Tone clone.   I'm new around here, so I only just now discovered the madbeanpedals PCB store!

These are the two circuits I'd most like to build:
https://www.madbeanpedals.com/projects/_folders/Classics/pdf/Mangler2020.pdf
(Fuzz Face)
https://www.madbeanpedals.com/projects/_folders/Classics/pdf/FuzzyBritches.pdf
(Jordan Boss Tone)

I'll research these Toshiba transistors, buy a TC1, order madbeanpedals PCBs and shop for parts. 
I suspect I'll be back here with more questions in a few weeks or months when I'm ready to start building.

Thanks for replying!  I'm glad to have stumbled upon this great forum!

WonkoTheSane

Yes, Crazy Face/Crazy Fuzz and original 2 transistor FY-2 have been known to use 2SB54, 2SB56 and 2SB175. The ones you have should be finr as long as hfe is 65-150 or so.
That which burns twice as bright, burns half as long.