Is this a germanium transistor?

7

70ssound

Member
Hello, and thank you for reading.
I got curious the other day and unscrewed the top of an electret condenser microphone I have and found what looks to be a germanium transistor. I was confused and surprised. This microphone is from the early 1970s, I'm thinking 1970 to 1973 based on research I've done. Anyhow, I just wanted to run it by the others; is this in fact a germanium transistor, or is it an early op amp? It seems rather late in the game to still be using a germanium transistor, no? I also seem to see a mixture of a carbon comp resistor and a carbon film! Thank you for looking.
From,
John
 

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Hi,
Metal can doesn't necessarily mean germanium.
I found some search results suggesting it's a silicon FET.
You'll get more results if you search "2SK24"
 
Thanks a lot for the info. You win a gift certificate to Carson's Ribs lol
I really can't believe I've never known about a metal can Si transistor. Wow.
 
70ssound said:
Thanks a lot for the info. You win a gift certificate to Carson's Ribs lol
I really can't believe I've never known about a metal can Si transistor. Wow.
Click to expand...
Whippersnapper! BC107,108,109, whole range of T05 can medium power and video devices. Also several PNP compliments of same!

Dave.
 
ecc83 said:
Whippersnapper! BC107,108,109, whole range of T05 can medium power and video devices. Also several PNP compliments of same!

Dave.
Click to expand...
I suppose now is the part where I should ask why these silicon transistors are encased in a metal can as opposed to their standard form we usually see?

Slouching Raymond said:
BCY70 on the tip of my tongue.
The 'Fuzz Face' (1966) used Germanium transistors.
Look at the component from the side, and count the legs.
Click to expand...

Hi there. I have a 1969 Sekova FA-II fuzz pedal that has two germanium transistors in it. It does sound really nice, and I have a deep respect for this pedal. I got it in 2013. I find myself loving this chrome pedal more and more. But in my reading about germanium transistors, I haven't really found an explanation for the strange, octave-harmonic type, almost synthesizer-like effect from these old pedals. I don't know much but it only seems to come from the ones with these germanium transistors.
 
Almost all germanium transistor came in metal cans. The BCs I mentioned were from Mullard but there were also Newmarket device in 'top hap' metal cans. This may have been a consequence of the manufacturing process or/and the fact that the transistors had piss poor heat tolerance and needed the extra 'sinking'? They also needed to be light tight.

Electronically, GTs had a much smaller voltage 'band gap', the VBe being only some 0.2V as against Si devices which arw 0.6 to 0.7V so you need to watch biasing arrangements if you swap the two types about. GTs also pass much more C-E leakage current than Si bu this is not important for pedal circuits (makes them noisier though)

GTs have much lower hfes (crudely, current gain) than Si. Rarely above 100 where Si tends to start and can approach 1000.
Even "audio" Si trannys have a frequency response well into RF, 10MHz no sweat. Ges are mostly done by 500kHz. Mind YOU! They did develop VHF Ge devices much later on so beware those if building a pedal with them! You would need some RFi filtering.

Dave.
 
Thank you for the information. When you really look at the inner workings of transistors you get an appreciation for how amazing they are. It's incredible to think people were smart enough back in the '40s/'50s to manipulate germanium and silicon atoms to create that band gap. I can only imagine how they were viewed as technological marvels in their time.
 
Well, I don't think they "manipulated" the band gap voltage? The parameters were set by the consequences of quantum mechanics which in turn were suggested by Maxwell's equations? ...NONE of which I hasten to add do I even begin to understand!

Dave.
 
ecc83 said:
Well, I don't think they "manipulated" the band gap voltage? The parameters were set by the consequences of quantum mechanics which in turn were suggested by Maxwell's equations? ...NONE of which I hasten to add do I even begin to understand!

Dave.
Click to expand...
I took a short primer on quantum mechanics but determined I really didn't possess the right tools for it.
 
Well you got a lot further than I did. Perhaps you guys can clarify this issue for me... I've always thought of transistors as heavily manipulated devices because the doping of a crystal with different materials is directly responsible for the conductive properties of the electrons in a transistor
 
70ssound said:
Well you got a lot further than I did. Perhaps you guys can clarify this issue for me... I've always thought of transistors as heavily manipulated devices because the doping of a crystal with different materials is directly responsible for the conductive properties of the electrons in a transistor
Click to expand...
Cor! Been a long time since I was taught this. Very pure Silicon is effectively an insulator* at room temperatures, as you say, the material is doped with minute concentrations of other elements and a PNP or NPN transistor formed. This is still an insulator across p-p or n-n until a current is passed through the np (say) junction. That current gives rise to the 0.6-0.7V B-E voltage we see for Si transistors.

I understand devices have been developed with even higher gap voltages such as Silicon Carbide and even Diamond?
Got to be the ultimate Audiophool amplifier? One with Diamond power transistors!!

*So too is Germanium but not so much and Ge starts to conduct at a much lower temperature than Silicon.

Dave.
 
Slouching Raymond said:
I made a germanium diode at university. Kept it in a matchbox. Don't know where the hell it is.
Click to expand...
Well of course the very first transistor was a point contact device using Galena, the stuff we used as a detector in "cat's whisker" radios. A German invention I believe but our US brothers don't like to talk about that!

Also, A.G. Bell did not invent the telephone! Technology is littered with people that never got the recognition they were due. "History" really does belong to the victors!

Dave.
 
70ssound said:
Hello, and thank you for reading.
I got curious the other day and unscrewed the top of an electret condenser microphone I have and found what looks to be a germanium transistor. I was confused and surprised. This microphone is from the early 1970s, I'm thinking 1970 to 1973 based on research I've done. Anyhow, I just wanted to run it by the others; is this in fact a germanium transistor, or is it an early op amp? It seems rather late in the game to still be using a germanium transistor, no? I also seem to see a mixture of a carbon comp resistor and a carbon film! Thank you for looking.
From,
John
Click to expand...
Its a FET 2SK24 is the part number. datasheet : https://www.myon98.net/memo/datasheet/2sk24.1971.pdf
Electret mics either have a common source amp built into them or external like this one.
 
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