Trying to sort out the transistor kit now. The transistor part numbers don't match the BOM or the Schematic, but here what I think is correct plus a couple of "calculated" resistors.
D1-D4 = SDUR60P60WT
Q3,Q4 = IRFP9240
Q5,Q6 = IRFP240Q7
Q7 = NPN = TIP31AG
Q8 = PNP = TIP32AG
R25,R26 = 10K .6 watt
R27,R28 = 4.75K .6 watt
R29,R30 = 475 .6 watt
D1-D4 = SDUR60P60WT
Q3,Q4 = IRFP9240
Q5,Q6 = IRFP240Q7
Q7 = NPN = TIP31AG
Q8 = PNP = TIP32AG
R25,R26 = 10K .6 watt
R27,R28 = 4.75K .6 watt
R29,R30 = 475 .6 watt
R25,26,27,28 can be what ever you want and need. This is what determinds the voltage your J-fets will see.
But R25 and R26 need to be the same. And R27 and R28 need to be the same.
Railvoltage/(R25+R27)*R27=cascode voltage.
But R25 and R26 need to be the same. And R27 and R28 need to be the same.
Railvoltage/(R25+R27)*R27=cascode voltage.
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Hi Bob - Were you simply asking the question in post #1231 or are you are building one of the non-cascode versions (V1 or V2) from the article?
It's tricky to keep track of all the different versions of this amp. If it's not a PITA, it may help to start any set of your posts with the version of the amp you're building along with the schematic you intend to use and/or point to an original post by you with that information. It will help a lot. If you start with the V3 schematic which is rationalized to the PCBs from the store, then you can mark up your schematic with "DNP", or something similar, for the parts that will not be populated for your specific build and update any part numbers, designations, or values you intend to use. It will help you and everyone here to keep track.
It may also be helpful to know what rail voltages you intend to run, if you intend to use Toshiba JFETs or LS JFETs at Q1 and Q2 in the article schematic, and any other helpful info you can provide re: your specific build.
It's tricky to keep track of all the different versions of this amp. If it's not a PITA, it may help to start any set of your posts with the version of the amp you're building along with the schematic you intend to use and/or point to an original post by you with that information. It will help a lot. If you start with the V3 schematic which is rationalized to the PCBs from the store, then you can mark up your schematic with "DNP", or something similar, for the parts that will not be populated for your specific build and update any part numbers, designations, or values you intend to use. It will help you and everyone here to keep track.
It may also be helpful to know what rail voltages you intend to run, if you intend to use Toshiba JFETs or LS JFETs at Q1 and Q2 in the article schematic, and any other helpful info you can provide re: your specific build.
I was considering a cascode V2 for no apparent reason. I'll stick with a normal V2 build which takes several questions off the table for me. I also found the attached BOM that shows the PN I actually have and their location. The part numbers of the transistors I have are not shown on any schematic I've looked at so far. Is there one out there that shows the IRFP9240 or IRFP240? If so I can't find it. But no big deal.
The case was finally delivered yesterday and the PS board is already built so I'm going to dive into it now and attempt now to drown.
Thanks for the continued support folks! I sincerely appreciate your time investment to help.
The case was finally delivered yesterday and the PS board is already built so I'm going to dive into it now and attempt now to drown.
Thanks for the continued support folks! I sincerely appreciate your time investment to help.
Since I didn't cascode, the information I needed was there. So not a problem but thanks for responding! The project is moving along nicely now. But we always think that until we plug it in, don't we? 😉
I would consider cascoding the J-fets if i where you.
With 32V rails you can go for: 32/(10Kohm+10Kohm)*10Kohm=16V
With 32V rails you can go for: 32/(10Kohm+10Kohm)*10Kohm=16V
6L6 I was attempting to follow your build at the front of this thread. I am using an AN-6224. Plus on page one you noted "Please remember that this build is showing the cascode circuit being used. It is not strictly necessary for 32V rails, but is required if you choose to use higher voltages. "and also" If building a v2, I would suggest not cascoding, simpler is better." which is always my policy. Am I OK with what I'm doing or do I need to circle back and cascode while it's still easy to do. Thanks for looking out for me gang!
Bob, if you do not cascode, it's recommended that you try to use lower Idss jfets to they don't run too hot. Cascode conveniently solves that also. 🙂
OK, I am thoroughly confused (yet again/continue to be/always) by this comment. So just use the transistors on the top of the output boards and leave off the diodes on the bottom?
yes. But turn the heatsinks around so you get the transistors on the bottom side and about 1/3 up on the sinks.
Thanks AudioSan. I will do that.
So is this correct going forward?
Q7 = NPN = TIP31AG
Q8 = PNP = TIP32AG
R25,R26 = 10K .6 watt
R27,R28 = 10K .6 watt
R29,R30 = 475 .6 watt
So is this correct going forward?
Q7 = NPN = TIP31AG
Q8 = PNP = TIP32AG
R25,R26 = 10K .6 watt
R27,R28 = 10K .6 watt
R29,R30 = 475 .6 watt
I suggest sticking with the original value of 4.75K for R27 and R28. That will give
you about 1/3 of the rail voltage across the jfets.
you about 1/3 of the rail voltage across the jfets.
OK. I have those resistors too.
Are the rest of those components correct? Especially Q7 and Q8 since the PN they are shipping isn't shown on a schematic or BOM that I can find.
Are the rest of those components correct? Especially Q7 and Q8 since the PN they are shipping isn't shown on a schematic or BOM that I can find.
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