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#181 |
diyAudio Member
Join Date: Jun 2011
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Thank you Biosonar for that info. It helps enormously.
I have thought that the J113/J175 version should have source resistors for power dissipation reduction. Now I will start a PCB for that configuration. While we are talking about the J113, my datasheet shows gate at the left-most pin. The actual JFET has gate at the right-most pin. What is the deal with that? For Idss, my J113 devices are all between 14mA and 28mA. I have tested hundreds. I bought a bag of 1000. Slowly working my way through them. My J175 devices are between 20mA and 24mA. I have tested 100. More are on the way. My assertion is that the combined Idss of each 1/2 of the buffer must match. The parallel buffer elements are all connected at the output. So, there will be a PCB for un-degenerated FJETs like the J270 and 2SK304. That pcb is on the way to me. There will be a pcb for degenerated JFETs like the J113 and J175. |
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#182 |
diyAudio Member
Join Date: May 2005
Location: Pennsylvania
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Here is another possibility for CCS mini-beast using the Toshiba 2Sk209 GB jfet. This design was suggested by Wayne from Pass Labs. Remove R4, R5 and add a gate resistor to the input:
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#183 | |
diyAudio Member
Join Date: Jun 2011
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Quote:
Rochester has good candidates for through-hole JFETs. I have ordered some to evaluate. I will also build J113/J175 through-hole versions. |
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#184 |
diyAudio Member
Join Date: Jun 2011
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After new information from Biosonar, I have changed the basic cell. Here is the schematic.
I have added G-D-S transistors. The original transistors are D-G-S. Now the builder can choose D-G-S devices or G-D-S transistors. You can choose one of each. The J113 is D-S-G and the J175 is D-G-S. These two can be used with this new board. Last edited by woofertester; 22nd January 2021 at 04:02 PM. |
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#185 |
diyAudio Member
Join Date: Jun 2011
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Here is the PCB.
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#186 |
diyAudio Member
Join Date: Jun 2011
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Both D-G-S and G-D-S pinouts are supported on this Mini B1 Beast
I am sorting the JFETs I have and have ordered additional types to characterize. You can also use all P-JFETs if you reverse the power supply polarities. Aye, Keptin. Reverse the polarities. Last edited by woofertester; 23rd January 2021 at 08:49 PM. |
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#187 |
diyAudio Member
Join Date: May 2019
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Sounds like "reworse".
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#188 |
diyAudio Member
Join Date: Jun 2011
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I have found a surplus JFET that is reasonably priced and has good gm and low noise. The limiting factor is that the device max voltage is 15v. If I want to use + / - 15v rails, is this a reasonable approach for the basic cell?
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#189 |
Official Court Jester
diyAudio Member
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well, not exactly
when you put more than one CCS in chain, there goes trouble go here and download some reading material: Erno Borbely site , zip file - for benefit of DIY community - Zen Mod Blog cascode them with bjts, shown in numerous Papa's thingies, same as in SissySIT etc.
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my Papa is smarter than your Nelson ! clean ![]() ![]() ![]() |
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#190 | |
diyAudio Member
Join Date: Jun 2011
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Quote:
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