I see that Ampslab.com has both types for a buck apiece if your purchase in twenty dollar lots--forty bucks for twenty 2SK170 and twenty 2SJ74. I might have to check into this baby!
🙂
🙂
I bought some from Shuro.de: check 2sk170 item no. 851706 (0,60e) and 2sj74 851707 (1,10e). BL version is ok.
Cambe said:
I believe that question has been answered a few pages back... One of the higher Idss versions
😉
Perhaps this question's been asked before: can the Fairchild 9240 fet be substituted for the IRFP9240. Fairchild's fets are substantially less money!
I have plenty of IRFP240 fets for the other half of the output (no need to purchase more); I just wondered if the Fairchild fet would mate to the IRF fet.
John🙂
I have plenty of IRFP240 fets for the other half of the output (no need to purchase more); I just wondered if the Fairchild fet would mate to the IRF fet.
John🙂
C1 and C2
Got a question on C1 and C2: what's the max. voltage across them? I have some good capacitors, but they are lower voltage spec parts.
Thanks!
Got a question on C1 and C2: what's the max. voltage across them? I have some good capacitors, but they are lower voltage spec parts.
Thanks!
Re: C1 and C2
We would need 5Vdc for the bias of the output mosfets.
On top of it, we would need to add 2Vrms input signal.
So, the maximum voltage across C1 or C2 would be about 11V
when the amp is operating as designed.
But, my preference is always the voltage rating of as big as the
rail voltage--just in case . . .
niner said:
We would need 5Vdc for the bias of the output mosfets.
On top of it, we would need to add 2Vrms input signal.
So, the maximum voltage across C1 or C2 would be about 11V
when the amp is operating as designed.
But, my preference is always the voltage rating of as big as the
rail voltage--just in case . . .
I am sorry if this has been covered before but how can one use another circuit instead of the tl431 type to balance the output fets?
protos said:
why?
if availability is reason - you can find them in every broken PC MoBo and PS
Yes availability was my main concern.We have a lot of good things here in Rio but access to electronic parts is lacking.I will have a better look around but I was wondering if there was a simple way around it.We just need a constant / adjustable bias voltage right?
I have scads of IRF9630 and 630 transistors. They have about half the wattage capacity of the 240 series, but do handle 200 volts.
They have lower transconductance, but since this is a unity gain amp, the lower transconductance probably wouldn't matter too much...
What do you guys think? Is this transistor capable of operating as the power component of the F4?
John🙂
They have lower transconductance, but since this is a unity gain amp, the lower transconductance probably wouldn't matter too much...
What do you guys think? Is this transistor capable of operating as the power component of the F4?
John🙂
Member
Joined 2002
Does any one have some suggestions for first power up of the F4, i mean after populating the boards wiring every thing up and double checking every thing, what should be done ? What should the pots be set at ?
Hints - Help ?
Hints - Help ?
P1 set to Maximum , P2 in the centre position (~ R5 value)
The reference voltage for a TL431 is 2.5 Volts.
With P1 set at 5K there's roughly 6 Volts across the gates of the OP T's, at the zero setting 8 Volts.
The reference voltage for a TL431 is 2.5 Volts.
With P1 set at 5K there's roughly 6 Volts across the gates of the OP T's, at the zero setting 8 Volts.
Member
Joined 2002
jacco vermeulen said:
Cool, i just don't want to blow this beast up, i just spend a good deal of money and time 🙂
Should a variac be used to power it up ?
You said P2 set to center position, ( ~R5 value ) does that mane set it to the value of R5 ?
Should i turn it on let it sit for a bit to warm up then set P2 to get 2.5V on TL431 ?
Sorry for the questions, with the alephs you just drop in a resistor an go 🙂
Jase