Which is why I suggested a diamond buffer - same thing with symmetrical drive capability. And you can buy them all one chip if you don’t want to bother matching the transistors yourself. “Best tool for the job” if you want a follower that runs open loop with no offset. The goal must actually be something else, if one insists on using germanium transistors.
I agree with Mark T's comments. Please explain why it has to be germanium?
Is it to obtain an "as was" repair/ new old design?
You can get silicon devices with Vceo's 40V or much higher. As others have said, you can also offset the Vbe with complementary devices (also easy to get with silicon) or an amplifier-buffer stage with NFB.
You can get audio frequency response from a slow-mo transistor. Even though the gain starts to fall at 10kHz as long as there is enough base drive the frequency can be pushed higher. But distortion will increase and there may be transient effects which spoil the results unless the drive current can, once again, be made low. In which case you may well need a driver of some sort in front of your output device. which makes silicon a far better choice.
Is it to obtain an "as was" repair/ new old design?
You can get silicon devices with Vceo's 40V or much higher. As others have said, you can also offset the Vbe with complementary devices (also easy to get with silicon) or an amplifier-buffer stage with NFB.
You can get audio frequency response from a slow-mo transistor. Even though the gain starts to fall at 10kHz as long as there is enough base drive the frequency can be pushed higher. But distortion will increase and there may be transient effects which spoil the results unless the drive current can, once again, be made low. In which case you may well need a driver of some sort in front of your output device. which makes silicon a far better choice.
I find females to be confused about what they want, and they like to keep us guessing.
Even here the purpose of the posts is not very clear.
The insistence on Germanium is odd, to say the least.
To quote wg_ski above: " The goal must actually be something else, if one insists on using germanium transistors."
I am not the only one to say that the OP is unclear, confused, or worse. Or more words along that line of thought.
Even here the purpose of the posts is not very clear.
The insistence on Germanium is odd, to say the least.
To quote wg_ski above: " The goal must actually be something else, if one insists on using germanium transistors."
I am not the only one to say that the OP is unclear, confused, or worse. Or more words along that line of thought.
@NareshBrd I know many , really a lot of women who'd be able to say the same things about men buying second hand or new audio equipment every month, bike parts, etc... especially loosing a lot of time building useless things in their view...but when it comes to audio equipment or 50 years old scrap components you'll find women completely uninterested with a subject where men are reportedly more deaf by 3...6db than women.Guess why!? My aunt who's 25 years older than me can hear 10 db softer sounds than I can!
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Rather unlikely as Vbe for silicon devices is commonly 0.65V or so, and the _entire bandgap_ of Ge is 0.67V, but if you factor emitter resistance at high currents Vbe can become quite large with either, but that's usually power devices pushed to the limits or Darlingtons.
Are you interested in low voltage operation then?
One of my early products was the MiniFahey guitar amplifier, around 1972 or so.
6" speaker, powered from 6 D cells which lasted forever, pull distortion knob, line/headphone/attenuator out, sold hundreds of them and were much used in Studio recordings, my "answer" to US made Pignose.
Its power amp came straight from a Philips applications datasheet and used AC187/188 as power transistors, extracting maximum power from such a lowly supply.
But that was the ONLY situation in which I found germaniums advantageous.
6" speaker, powered from 6 D cells which lasted forever, pull distortion knob, line/headphone/attenuator out, sold hundreds of them and were much used in Studio recordings, my "answer" to US made Pignose.
Its power amp came straight from a Philips applications datasheet and used AC187/188 as power transistors, extracting maximum power from such a lowly supply.
But that was the ONLY situation in which I found germaniums advantageous.
"StevenStanleyBayes, why does the base-emitter voltage matter so much? Can't you use a PNP emitter follower followed by an NPN emitter follower, so the base-emitter voltages more or less cancel?"
Example: Simulation of AC128 1k emitter load +/-10V supply offset 250mV; BC557/BD139 pair, 10k load first stage 1k load second stage offset 2.5mV - less than the Vbe of the AC128!
Do you need DC coupling? If AC coupled Vbe is almost irrelevant operating at up to 40V.
Example: Simulation of AC128 1k emitter load +/-10V supply offset 250mV; BC557/BD139 pair, 10k load first stage 1k load second stage offset 2.5mV - less than the Vbe of the AC128!
Do you need DC coupling? If AC coupled Vbe is almost irrelevant operating at up to 40V.
Now that you mention it, yes.
Pignose still used driver and output transformers.
They still do, although even they upgraded to Silicon, a pair TIP41A
Hear hear StevenStanleyBayes 🙂
Pignose still used driver and output transformers.
They still do, although even they upgraded to Silicon, a pair TIP41A
Hear hear StevenStanleyBayes 🙂
We had a poster called Somerset who wanted a rhodium plated connector, just because he/she did not want an extension cord.
I thought she was confused too.
And we do have people who think their idea is unique, only it died 20 years back.
But look at Tesla...old idea, new style. Made an electric car work, the idea itself is old, but they made all the car companies come around to the idea of electric cars.
Still, the OP is not saying why he / she wants Germanium transistors.
I thought she was confused too.
And we do have people who think their idea is unique, only it died 20 years back.
But look at Tesla...old idea, new style. Made an electric car work, the idea itself is old, but they made all the car companies come around to the idea of electric cars.
Still, the OP is not saying why he / she wants Germanium transistors.
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"Still, the OP is not saying why he / she wants Germanium transistors."
Are you an idiot or what?
http://www.steven-stanley-bayes.com/Gallery.html
Are you an idiot or what?
http://www.steven-stanley-bayes.com/Gallery.html
The gallery does not tell me the purpose of using Germanium transistors.
Appears to be male, or could be a cross dresser.
And why should anybody take the trouble of finding that person on the net?
I have better things to do than being stupid. Or be called an idiot.
Bye Bye
Appears to be male, or could be a cross dresser.
And why should anybody take the trouble of finding that person on the net?
I have better things to do than being stupid. Or be called an idiot.
Bye Bye
It's his topic an he doesn't have an obligation to tell you anything, especially the nature of his sexual organs ...His quetions were already answered.f...off!
I assembled several Ge output power buffers along the Ciuffolli Follower lines.
I can state, that Ge power transistors allow to achieve output impedance of amplifier in the range of 0,01...0,015 Ohms without any Negative Feedback Loop !
This is absolutely not possible with Si power transistors, usually one achieves around 0,1 Ohms in the emitter follower configuration. Si transistor has theoretical limit 0,025 Ohms, but essential base region resistors is added to this value.
Main difference between Ge and Si is in valuee of intrinsic base region resistance. This parameter is well determined and explained. Ge is better conducting, therefore intrinsic resistance of the base region of Ge transistors is much lower than of Si.
Compared sound of original Ciuffolli Follower and Ge follower, the last gives better articulated bass and more "open" sound.
Considering ohmic resistance of real world voice coils the difference of output impedance between 0.01 and 0.1 Ohms is neglible, personal sound comparisons are pure anecdotal.
I have no idea what triggered that.
It is not clear why he is supporting the OP.
It is also not yet clear why the OP is insisting on Ge devices.
As an aside, can a Wheatstone Bridge be modified to a audio circuit with the pre amp output in place of the galvanometer?
How good is a BUF634 diamond buffer chip?
Can it be used here, if available?
It is not clear why he is supporting the OP.
It is also not yet clear why the OP is insisting on Ge devices.
As an aside, can a Wheatstone Bridge be modified to a audio circuit with the pre amp output in place of the galvanometer?
How good is a BUF634 diamond buffer chip?
Can it be used here, if available?
To bucks bunny: You have a right for this point of view, theoretically it is correct. But practice is much variable.
But you know the difference between theory and praxis? Theoretically none😛
But seriously - I know this hype around excessive damping since the seventies. It is a myth, and utterly boring. And I know that not one single person believing the contrary can be convinced by arguments.
But seriously - I know this hype around excessive damping since the seventies. It is a myth, and utterly boring. And I know that not one single person believing the contrary can be convinced by arguments.