jmateus:
I have replied to your E-mail four times. I know the first 3 failed for some reason. Did you receive the 4th?
I have replied to your E-mail four times. I know the first 3 failed for some reason. Did you receive the 4th?
Re: Q matching
You can get excellent results without matching. There are different opinions on matching on this forum about the necessity of doing so. I match for everything I build because it gives me something to do with my curve tracer.
lgreen said:
You can get excellent results without matching. There are different opinions on matching on this forum about the necessity of doing so. I match for everything I build because it gives me something to do with my curve tracer.
Re: thanks
I like your web site. You are quite the DIY kind of guy! I doubt that many here have built that many projects.
lgreen said:
I like your web site. You are quite the DIY kind of guy! I doubt that many here have built that many projects.
Re: Re: thanks
That I am able to make anything is a testiment to you guys who post designs and answer questions. I cannot understand the circuits with a transistor but can do fine with opamps and volt. regulators. I am someone who can stuff a board and make basic measurements, but generally cannot do the math (sorry AndrewT) and I have limited time so don't want to read the Self and other books. So I like to make stuff but couldn't do it without you guys.
Steve Dunlap said:
That I am able to make anything is a testiment to you guys who post designs and answer questions. I cannot understand the circuits with a transistor but can do fine with opamps and volt. regulators. I am someone who can stuff a board and make basic measurements, but generally cannot do the math (sorry AndrewT) and I have limited time so don't want to read the Self and other books. So I like to make stuff but couldn't do it without you guys.
Re: Re: Re: thanks
Hi lgreen - You do have a way of doing very practical things tho - 😀
For example - I like the way you took an old amp chassis and used it for your case. I just scored an amp for parts (cheap) and I'm adopting your idea to use it as a case for my Krills. So we are all learning from each others ideas - and that is what DIY is all about. 😉
lgreen said:
Hi lgreen - You do have a way of doing very practical things tho - 😀
For example - I like the way you took an old amp chassis and used it for your case. I just scored an amp for parts (cheap) and I'm adopting your idea to use it as a case for my Krills. So we are all learning from each others ideas - and that is what DIY is all about. 😉
Matching once again
My assembly is proceeding slowly but steadily..
I'm ready to solder my matched pairs of transistors but I'm not sure if I identify the pairs correctly....
I think that the pairs should be as follows
Q1-Q2
Q7-Q10
Q8-Q11
Q9-Q12
am I right ?
(Steve you can't get along with this ...hahaha 🙂 )
My assembly is proceeding slowly but steadily..
I'm ready to solder my matched pairs of transistors but I'm not sure if I identify the pairs correctly....
I think that the pairs should be as follows
Q1-Q2
Q7-Q10
Q8-Q11
Q9-Q12
am I right ?
(Steve you can't get along with this ...hahaha 🙂 )
Re: Matching once again
Correct –
Also outputs Q13 - Q15, Q14 – Q16, Q19 – Q20 (on 100w amp) 😀
Marinos said:
Correct –
Also outputs Q13 - Q15, Q14 – Q16, Q19 – Q20 (on 100w amp) 😀
Matching continued
If matching parameter is Hfe it should be the same in a pair or it should have an intended difference ?
I'm asking because using my DMM I mesaure 1837s around 170 and 4793s around 155. Having some spare of both I could find some better matches 😉
If matching parameter is Hfe it should be the same in a pair or it should have an intended difference ?
I'm asking because using my DMM I mesaure 1837s around 170 and 4793s around 155. Having some spare of both I could find some better matches 😉
matching hFE using the built DMM tester is a waste of time.
Build a test jig that maintains the SAME Vbe across the tested pair and check that the Ic or Ie are very close.
Clip the pair together so that they are near matching temperature.
If Vce is matching and Vbe is matching and Ic is matching then power dissipated will also match. This and the thermal coupling ensures that the Tj is very close to matching.
If Tj varies then you cannot check for matching Vbe and hFE.
Build a test jig that maintains the SAME Vbe across the tested pair and check that the Ic or Ie are very close.
Clip the pair together so that they are near matching temperature.
If Vce is matching and Vbe is matching and Ic is matching then power dissipated will also match. This and the thermal coupling ensures that the Tj is very close to matching.
If Tj varies then you cannot check for matching Vbe and hFE.
Hi Andrew,
Thanks for your reply. My question rised because the matched pairs comes from Steve and I don't Know the matching procedure.
Is the test jig you are describing is similar to the one that I match Idss of jfets ? I suppose you measure Ic or Ie placing a resistor to the appropriate leg. Any reference to a schematic ? Googling gives a lot but not all of them are similar.
Thanks for your reply. My question rised because the matched pairs comes from Steve and I don't Know the matching procedure.
Is the test jig you are describing is similar to the one that I match Idss of jfets ? I suppose you measure Ic or Ie placing a resistor to the appropriate leg. Any reference to a schematic ? Googling gives a lot but not all of them are similar.
Marinos said:
Hi Marinos,
I use an instrument made for testing transistors. I could buy 8 or 10 good DMMs for what it cost, so I hope it is more accurate. I can no longer do the matching myself. I trust the person doing the matching to follow directions.
Thank you both Andrew and Steve,
If I combine your answers I'll use the pairs as they came.
I understand that using an Instrument for matching (or a special test jig) doesn't mean just equal Hfes 😉
If I combine your answers I'll use the pairs as they came.
I understand that using an Instrument for matching (or a special test jig) doesn't mean just equal Hfes 😉
Using an External Bridge (pair)
I've started to build my Krill and hooked up my power supply, it uses an external pair of bridge rectifiers that I happened to have laying around and the intent was to feed rectified 35V to the boards in phase and out of phase, bypassing the big regulator diodes that are on the board.
I see that its more complicated than this...or is it? Has anyone done this before or is anyone able to tell me what to connect where?
I've started to build my Krill and hooked up my power supply, it uses an external pair of bridge rectifiers that I happened to have laying around and the intent was to feed rectified 35V to the boards in phase and out of phase, bypassing the big regulator diodes that are on the board.
I see that its more complicated than this...or is it? Has anyone done this before or is anyone able to tell me what to connect where?
Re: Using an External Bridge (pair)
It shouldn't be more complicated than this. You are simply substituting one bridge for another. Make sure your polarities are correct.
lgreen said:
It shouldn't be more complicated than this. You are simply substituting one bridge for another. Make sure your polarities are correct.
I would agree if I had a single bridge. But as I said I have a pair of bridges, to separately rectify each phase (like those chipamp power supplies with 8 diodes); and the rectified AC phases connect to each other forming ground after the bridges. The board needs pre-rectified AC with a common ground that does not exist in my dual bridge setup.
lgreen -- Are you using the Krill board from Steve or your own? If you're using Steve's board you have to deal with the two different power supplies that are on the board. If you're using outboard supplies similar to the gain clones, you can connect where the big capacitors (C13 and C14) would normally be and then jumper over to the output of the two zener/pass transistor regulators. It's not a good solution as you lose regulation and the higher voltage rails for the voltage gain stage but it works. You still need to keep the local bypasses on the Krill board.