BUFFER FOR BLUES...
I am posting this as general interest rather than burying it
in an existing thread. It is a JFET input buffer for the ZV4.
It has not been tested.
😎
I am posting this as general interest rather than burying it
in an existing thread. It is a JFET input buffer for the ZV4.
It has not been tested.
😎
Member
Joined 2002
Nelson Pass said:
Wow, straight from the Zen Master! Thank you, sir. I am currently playing around with a buffer jfet connection like you described at the other thread. The voltage gain is still quite high and I'm trying to find a way to lower it. I'll just scrap that and use this one. I can only sim it right now because my Woody Zen is in WA state...I'm in Californi-A!
The Source voltage on the JFET should be 10V not 13V.
Right now the weather is perfect in California.
😎
Right now the weather is perfect in California.
😎
Member
Joined 2002
Nelson Pass said:
Superstitious ?
Supposing the mentioned 2SK170 or 2SJ74 for the JFet.
Any other suggestion for a JFet (and where to get it)?
Allan, can you already vision the 8th Blues Buffer version ?(no W!)
Weather sucks big time overhere , but don't let that discourage you guys.
Maybe it isn't necessary to use the excotic Hitachi devices?
Would these be usefull for the JFET-buffer?
http://www.onsemi.com/pub/Collateral/2N5460-D.PDF
Steen😎
Would these be usefull for the JFET-buffer?
http://www.onsemi.com/pub/Collateral/2N5460-D.PDF
Steen😎
jacco vermeulen said:
Jacco,
NP superstitious? I've seen some of his mosfets biased at about 666.7mA
Next will be "Blues Buffer's Brother".
Steenoe, as designed by NP any Jfet that can take Vds=10V or more and about Ids=140mA(?) or more.
I was kinda wondering myself too if one of ON JFET's are any good.
ON does produce quite a bunch of them.
Actually i was more thinking of an Elliot's challenger when i read 666s :
"Blues Buffer B**ch"
Somehow i always visualise Rod as Darth Vader.
ON does produce quite a bunch of them.
Actually i was more thinking of an Elliot's challenger when i read 666s :
"Blues Buffer B**ch"
Somehow i always visualise Rod as Darth Vader.
On Semi parts work just fine. Get as high an Idss & high transconductance part as they offer.
No reason to get boggled, it's a Source follower, just 'upside down' due to the input being a P device.
Enjoy.
Grey
No reason to get boggled, it's a Source follower, just 'upside down' due to the input being a P device.
Enjoy.
Grey
I have the 2N5462 designed into the front end of my PLH proto(similar to fig;5). I'll be lighting it up for the first time today😀 😀 😀 The 2N5460 series seems to be quite high on the noise figure but I did not get to excited over to many other ON devices... I've never done anything J-FET before. We will see where I end up.
Zen v4jfet Cascoded
Found time to look for the lost brother. Anybody care to try this? Comments? Let me know if I missed something.
The jfet will dissipate about 100mW. Using the 2sj74 it will have about 4x safety margin with about 7V of stable Vds across.
Has anybody tried lower than 10Vds on a 2sj74 and still kept the coveted jfet sound? Now if only the guy selling 2sj74s will get back with me I'll have something to do this Christmas holiday.
Allan
Blues said:
Found time to look for the lost brother. Anybody care to try this? Comments? Let me know if I missed something.
The jfet will dissipate about 100mW. Using the 2sj74 it will have about 4x safety margin with about 7V of stable Vds across.
Has anybody tried lower than 10Vds on a 2sj74 and still kept the coveted jfet sound? Now if only the guy selling 2sj74s will get back with me I'll have something to do this Christmas holiday.
Allan
Hi Blues. Where do you get the SJ74? I just had a bunch from Ruach, selling J-fets in the "Marketplace" 🙂 Actually the postman delivered them today🙂
Nice schematic indeed, thanks for posting.
Steen😎
http://www.diyaudio.com/forums/showthread.php?s=&threadid=86778&perpage=10&pagenumber=1
Nelson, I would have a pulldown resistor at the input just to avoid accidental charging of the input cap. Resisitor value 100k-1M
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