Hi, Walter Burkhart
Indeed it makes a dioda if the collector/base is more positive than the emitor. But in here, the emitors are more positive, like inversed diode.
What happened to a transistor treated this way?
Indeed it makes a dioda if the collector/base is more positive than the emitor. But in here, the emitors are more positive, like inversed diode.
What happened to a transistor treated this way?
It's a zener diode, at about 7 volts, which is a typical
E-B breakdown voltage. Check to make sure though,
as some bipolar fab processes yield different voltages.
E-B breakdown voltage. Check to make sure though,
as some bipolar fab processes yield different voltages.
No doubt I believe you, you sometimes do have that tendency 😉 which we all like I presume.
Only from a commercial point of view, two transistors are more expensive than a zener. Well, for mass consumer products that would be the consideration.
/Hugo
Only from a commercial point of view, two transistors are more expensive than a zener. Well, for mass consumer products that would be the consideration.
/Hugo
I've noticed this for quite some time, but since the .jpg is kind of blurry, I think it is a misdirected arrow. But once I got another sch that uses this, and the arrow and the marking A42 is clear, I know, I haven't recognize this kind of transistor usage.
Does everyone here knows this except me?
Netlist said:
Depends on whether you have large boxes of A42's that fall out
of the selection process.
😎
Something else you might not know is that the typical
bipolar transistor works backward (exhange C for E)
but not a rated voltage - The BE breakdown voltage is
the limit.
bipolar transistor works backward (exhange C for E)
but not a rated voltage - The BE breakdown voltage is
the limit.
That pretty much answers the question in post #2.
But what are A42's? I did find 2SA42 but that's an old germanium...and PNP 😕
/Hugo
But what are A42's? I did find 2SA42 but that's an old germanium...and PNP 😕
/Hugo
MPSA42...a good, cheap, low noise NPN transistor. Every well-stocked parts bin should have a few. A highly recommended part.
Grey
Grey
In Threshold/Statis design I found many not usual things, but as I experimented it usually results in good sounding.
One aspect is the degeneration RE. In books or commercial schematics, seldom use bigger than 0.22ohm. In your design (majority) it never less than 0.68ohm, more likely 1ohm.
Mr. Pass,
Some designs don't use RE for bipolar EF output stage. I tried this and tried 1ohm RE for single EF pair (not parrareled), they do exhibit different sound characteristic. I first tought big RE is not good, since it will introduce more xover switching distortion. But from experiment, big RE does the opposite way, the sound is more relaxed to hear. The handbooks suggest opposite direction 😀
In the terms of sound quality (not talking about current sharing in parrareled output stage), what is the importance of RE or big valued RE? What is your personal opinion on EF complementary output stage that don't use RE (just connecting Emitor-Emitor-output line)?
One aspect is the degeneration RE. In books or commercial schematics, seldom use bigger than 0.22ohm. In your design (majority) it never less than 0.68ohm, more likely 1ohm.
Mr. Pass,
Some designs don't use RE for bipolar EF output stage. I tried this and tried 1ohm RE for single EF pair (not parrareled), they do exhibit different sound characteristic. I first tought big RE is not good, since it will introduce more xover switching distortion. But from experiment, big RE does the opposite way, the sound is more relaxed to hear. The handbooks suggest opposite direction 😀
In the terms of sound quality (not talking about current sharing in parrareled output stage), what is the importance of RE or big valued RE? What is your personal opinion on EF complementary output stage that don't use RE (just connecting Emitor-Emitor-output line)?
- Status
- Not open for further replies.