Parts....
mike_diy,
You may be met with resistance on this unless you formulate a BOM, something Ed LaFontaine suggested earlier. Basically, without doing the work, (or at least some of it), people are reluctant to help around here. It also shows that you want to help the collective by offering up a BOM that helps everyone if correct.
If you compile the BOM with supplier, brand, part (value, voltage, current, etc...), supplier part number, and quantity, people will have something to comment on. Without it, people will say whatever they want like, "Mmm, hard to believe all i want is a pair of pyjamas".
Nelson does say what resistors he uses in the Ax article, and sites manufacturers for the FET's as well. If you look around a bit in other threads you will see what others have used for other PassDIY/Fx projects. Lastly, Peter Daniel and other have posted their own personal opinions on different parts in different circuits and different locations. Someone once told me "There is no such thing as a free lunch and nothing more expensive than a free drink."
Chris
mike_diy,
You may be met with resistance on this unless you formulate a BOM, something Ed LaFontaine suggested earlier. Basically, without doing the work, (or at least some of it), people are reluctant to help around here. It also shows that you want to help the collective by offering up a BOM that helps everyone if correct.
If you compile the BOM with supplier, brand, part (value, voltage, current, etc...), supplier part number, and quantity, people will have something to comment on. Without it, people will say whatever they want like, "Mmm, hard to believe all i want is a pair of pyjamas".
Nelson does say what resistors he uses in the Ax article, and sites manufacturers for the FET's as well. If you look around a bit in other threads you will see what others have used for other PassDIY/Fx projects. Lastly, Peter Daniel and other have posted their own personal opinions on different parts in different circuits and different locations. Someone once told me "There is no such thing as a free lunch and nothing more expensive than a free drink."
Chris
mike_diy said:
I am just asking recommended parts.
Not alternative parts, resources or PCB……papajammies
Be nice or I’ll bring democracy to your home
At last!!Democracy is found!!You had it all the time ,I bet.
As for parts the only question I had was the wattage on the jfet bias resistors. Someone said 3watts ;I said too big. Other than that question everything else was covered by NP. Looking through his many design article he has been casually specific that SUPER parts were not needed. I did all the parts from Mouser ,online, in an hour with delivery in three days. Opps..Had the jfets from Jackinnj...The Country Store.
Juma,
The only thing I would offer is with respect to the position of the outputs on such a compact board. Your layout makes the 2 of them a virtual point source of heat. It may benefit if they were rotated out onto opposite sides of the board. This would effectively give them more heatsink within which to dispense their heat. This does depend upon a particular heatsink you may have in mind. The article references TWO 8" X 6" sinks per channel. There is plenty of room.
The only thing I would offer is with respect to the position of the outputs on such a compact board. Your layout makes the 2 of them a virtual point source of heat. It may benefit if they were rotated out onto opposite sides of the board. This would effectively give them more heatsink within which to dispense their heat. This does depend upon a particular heatsink you may have in mind. The article references TWO 8" X 6" sinks per channel. There is plenty of room.
Yes, it does appear to be a possible optimization point, but I prefer this type of arrangement which offers a benefit of shorter traces in output section. However, I never experienced a problem in practice with "point source of heat" (I built Aleph and F4 this way) approach, so I'll stick to it (Aluminum is fast enough heat conductor, I suppose).
Thank's for input, Ed !
kraljmatjaz said:
Sorry, no, I don't have the means for that, but everyone is is free to do whatever he likes with it. I'll just make two pieces for me (home production)
Zen Mod said:
yeah ...... hotrod-ing is usual thing in Serbia .......
(I'm driving '84 hotrod-ed Stojadin ........ what's few hot mosfets comparing to that .....)
Especially when rods glow in the dark
jacco vermeulen said:
Yes, that's Stojadin !
Here is a headphone amplifier looking very much like a bipolar F5...
http://users.otenet.gr/~ATHSAM/headphone_2.htm
http://users.otenet.gr/~ATHSAM/headphone_2.htm
I saw this on the simulation, and had to see in real life. The response continues to rise the output was 2.83V into 8 ohms. I let the amp cook at 1.3 Amps, 24V for an hour and it stabilizes quite nicely. The heat sink is cooled with forced air at around 100LFM.
Simulation:
Results at 1W into 8 ohms:
(the AP only goes to 200kHz)
Simulation:
An externally hosted image should be here but it was not working when we last tested it.
Results at 1W into 8 ohms:
(the AP only goes to 200kHz)
An externally hosted image should be here but it was not working when we last tested it.
I built one channel with an IRfp240 and the Fairchild P channel
part named in the article, so I'm going to assume that the primary
issue is the IRFP9240.
Somehow I remembered commenting in the article about the
IR version of the IRF9240 with regard to the performance, but going
back, it appears that I probably remember it from this thread.
The IRFP9240 from IR suffers from the high frequency shelving of
the transconductance figure which makes it difficult to use in
Common Source applications. You need to replace it with a 9240
made by Harris or Fairchild (or anybody else). I used the Fairchild
FQA12P20 with good results, the ones you saw in the curve.
I recommend that you get a pair of FQA12P20's from Mouser as
a start.
The IRFP9240 from IR accounts for the second harmonic, which you
will probably note favors the + half of the output with increased
amplitude (2nd harmonic), and you should also see that this effect
occurs from the mid audio band up and is not seen at low frequencies.
This stems from the decreased gain of the P channel device.
The response peak on the top is likely also an artifact, and if it's
still there after replacing the P devices, there's a number of ways
to tweak it out. Alternately if you don't mind the distortion figure
of the IR P channel parts, we can tweak those for flatter response.
Last question, what is your supply voltage?
part named in the article, so I'm going to assume that the primary
issue is the IRFP9240.
Somehow I remembered commenting in the article about the
IR version of the IRF9240 with regard to the performance, but going
back, it appears that I probably remember it from this thread.
The IRFP9240 from IR suffers from the high frequency shelving of
the transconductance figure which makes it difficult to use in
Common Source applications. You need to replace it with a 9240
made by Harris or Fairchild (or anybody else). I used the Fairchild
FQA12P20 with good results, the ones you saw in the curve.
I recommend that you get a pair of FQA12P20's from Mouser as
a start.
The IRFP9240 from IR accounts for the second harmonic, which you
will probably note favors the + half of the output with increased
amplitude (2nd harmonic), and you should also see that this effect
occurs from the mid audio band up and is not seen at low frequencies.
This stems from the decreased gain of the P channel device.
The response peak on the top is likely also an artifact, and if it's
still there after replacing the P devices, there's a number of ways
to tweak it out. Alternately if you don't mind the distortion figure
of the IR P channel parts, we can tweak those for flatter response.
Last question, what is your supply voltage?