gszekeres - I spelled it wrong
or szekeres
his name is Greg Szekeres
this search did WELL:
http://www.diyaudio.com/forums/sear...id=80608&sortby=lastpost&sortorder=descending
last six month
I would recommend tortello thread
or szekeres
his name is Greg Szekeres
this search did WELL:
http://www.diyaudio.com/forums/sear...id=80608&sortby=lastpost&sortorder=descending
last six month
I would recommend tortello thread
Hello,
Here is one PSU you might be looking for.
But then you should be very careful with 40,000uF.
Enjoy!
Traderbam -
"In any case, this design does not require matching as it is single-ended."
Cool. I did not know that. This would make my life easy indeed.
And like you have said, I think DC coupled operation isn't so ... nice. Offset is annoying to play with for lazy bum like myself. I got fed up and never tried again. But I think you will be happy with coupling caps.
Don't worry, I will try some BJT when I get a chance. I never said they are bad. I found it difficult to play with ... back when I was building this amp. ... darn 3~4 years ago! Now I do play with BJT.
Tomo
Here is one PSU you might be looking for.
An externally hosted image should be here but it was not working when we last tested it.
But then you should be very careful with 40,000uF.
Enjoy!
Traderbam -
"In any case, this design does not require matching as it is single-ended."
Cool. I did not know that. This would make my life easy indeed.
And like you have said, I think DC coupled operation isn't so ... nice. Offset is annoying to play with for lazy bum like myself. I got fed up and never tried again. But I think you will be happy with coupling caps.
Don't worry, I will try some BJT when I get a chance. I never said they are bad. I found it difficult to play with ... back when I was building this amp. ... darn 3~4 years ago! Now I do play with BJT.
Tomo
Tomo
don't you think the PS design you posted has too large capacitors, and inductors, for a szekeres?
I was thinking about 2*4700µF and 2.2 or 4 mH
4*12000µF is the same capacity that is used on a ZenV4 PS (for speakers, not for headphones!)
don't you think the PS design you posted has too large capacitors, and inductors, for a szekeres?
I was thinking about 2*4700µF and 2.2 or 4 mH
4*12000µF is the same capacity that is used on a ZenV4 PS (for speakers, not for headphones!)
Hello,
RJM has used this design in his Szkeres-JFet alternative. So it works. I guess if you know how to do it right, you can have as much capacitance as you want.
Vripple2 = Vripple1*1.77/(L * C)
L is in Henry.
C is in micro-farad.
So in your case.
Vripple2/Vripple1=0.085
with L = 2.2mH, C = 4700uF X 2.
That I think is a good value.
Tomo
RJM has used this design in his Szkeres-JFet alternative. So it works. I guess if you know how to do it right, you can have as much capacitance as you want.
Vripple2 = Vripple1*1.77/(L * C)
L is in Henry.
C is in micro-farad.
So in your case.
Vripple2/Vripple1=0.085
with L = 2.2mH, C = 4700uF X 2.
That I think is a good value.
Tomo
Oops
I've juste seen that it's written "only for lightning" on my transformer :/
is this important?
I've juste seen that it's written "only for lightning" on my transformer :/
is this important?
damn
my resealer has no more IRF510, nor 512 513...
only 520, that has different specs :/
Is there a good alternative?
my resealer has no more IRF510, nor 512 513...
only 520, that has different specs :/
Is there a good alternative?
no problem, I should buy it
Even an IRF530 would do, although it has somewhat higher input capacitance
Even an IRF530 would do, although it has somewhat higher input capacitance
Bricolo/Tomo,
Kristjan replied that the power supply is not regulated because it isn't. It is "smoothed" or "filtered" but not regulated. It is the unregulated kind. What is recommended for this amp is a regulated supply if I have quickly read the thread and the first schematic right. That means an ACTIVE regulator supply. This could be anything from an LM317/LT1086 or other linear regulator chip to some discrete regulator of some kind.
/UrSv
Kristjan replied that the power supply is not regulated because it isn't. It is "smoothed" or "filtered" but not regulated. It is the unregulated kind. What is recommended for this amp is a regulated supply if I have quickly read the thread and the first schematic right. That means an ACTIVE regulator supply. This could be anything from an LM317/LT1086 or other linear regulator chip to some discrete regulator of some kind.
/UrSv
Yes Bricolo. The mosfet that FA Schmidt used is the Hitachi 2SK216. It can be had at MCM Electronics.
G
G
OK, now I'm sure it's the 2SK216
thanks
but now, since it has other specs that the IRF510, I need to re-calculate every resistor value
How can I do this? Can you give me some formulas?
fa-schmidt hasn't said the values he used :/ he only said the bias current he used fot the 2sk216 was 250mA
what is the bias current?
thanks
but now, since it has other specs that the IRF510, I need to re-calculate every resistor value
How can I do this? Can you give me some formulas?
fa-schmidt hasn't said the values he used :/ he only said the bias current he used fot the 2sk216 was 250mA
what is the bias current?
200-250 is well enough for driving evenBricolo said:
low impedance 32 ohms Headphones in a perfect way.
no need to make the transistor operate too hot
Cool transistors work well
but what is the bias current?
is it the gate current (seems too high for being this), the input current, the output current...
is it the gate current (seems too high for being this), the input current, the output current...
ok
so, we aproximate that I(D)=I(S)
or are Mosfet not like bipolar transistors? I mean, on a bipolar transistor, I(C)=I(B)+I(E)
so, we aproximate that I(D)=I(S)
or are Mosfet not like bipolar transistors? I mean, on a bipolar transistor, I(C)=I(B)+I(E)
No. For a FET there is no current flowing in through the Gate as such. I(D) = I(S) in the cases where no other currents are present. In case of an amp there will be some current going to the load so in this case it is not true. In this case it is 250 mA when the amp is not used i.e. the DC bias current.
/UrSv
/UrSv
Ok
so, fa-schmidt uses 250ma bias current (I still don't know how he calculated this, and why he uses this value)
for class A, we want Vds=Vcc/2, I am right
so, it Vcc=15V, we must adjust Vds to 7.5V
am I right?
so, fa-schmidt uses 250ma bias current (I still don't know how he calculated this, and why he uses this value)
for class A, we want Vds=Vcc/2, I am right
so, it Vcc=15V, we must adjust Vds to 7.5V
am I right?
The ouptut will be in class A no matter where your bias point is. There is only one device in the circuit. The voltage at the gate is biased a 2/3 of the VDD. In other words 10 volts. There is no current flow through the gate to source( or there is so small an amount that it is insignificant). Use Rs to adjust the current flow through the FET.
G
G