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"Inverted" Aleph J?
"Inverted" Aleph J?
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Old 23rd December 2017, 12:17 AM   #21
xrk971 is offline xrk971  United States
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"Inverted" Aleph J?
Quote:
Originally Posted by juma View Post
Xrk,
take care about polarities - bottom PSU rail is in this schematic positive
Yes, I saw that and was wondering if I should flip the schematic vertically to keep with top flows down convention?
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Old 23rd December 2017, 12:35 AM   #22
juma is offline juma  Germany
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Helpfull conventions are nice
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Old 23rd December 2017, 12:42 AM   #23
Zen Mod is online now Zen Mod  Serbia
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"Inverted" Aleph J?
Quote:
Originally Posted by xrk971 View Post
I saw your question after I updated the schematic as I got to the later post where Juma corrected it.

The manufacturer’s spec sheet says it’s interchangeable. I have built circuits thus and that appears to be a true statement. Why is that the wrong answer?

https://www.nxp.com/docs/en/data-sheet/BF862.pdf

not to be nit-picky , but one thing is how you're drawing schematic , and another thing is that part is having interchangeable electrodes ;

in that circuit , and all circuits on earth , LTP is having cathodes/emiters/sources in tail ; put any other electrode there , and it's no longer LTP

fact that with BF862 ( and good number of JFets ) you can turn them upside down is sort of lucky coincidence , but also one you don't need to overuse

I didn't study/search are there any consequences ( voltages, capacitances) but frankly I wasn't so keen to use that convenience at all .... sort of keeping with convention
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Old 23rd December 2017, 12:44 AM   #24
xrk971 is offline xrk971  United States
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"Inverted" Aleph J?
Quote:
Originally Posted by Zen Mod View Post
not exactly always ...... and also not exactly figure carved in stone by Papa
The words “assuming” and “typical” don’t tie the 1.2amp bias down to anything in stone. Simply as an example to guess what kind of dissipation and power output could be.

Quote:
in that circuit , and all circuits on earth , LTP is having cathodes/emiters/sources in tail ; put any other electrode there , and it's no longer LTP
If flipped upside down, it would maybe be called a LNP (Long Neck Pair)
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Last edited by xrk971; 23rd December 2017 at 01:01 AM.
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Old 23rd December 2017, 01:00 AM   #25
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Old 23rd December 2017, 06:22 PM   #26
Nelson Pass is offline Nelson Pass  United States
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"Inverted" Aleph J?
You do need to use the Harris IRFP9140 devices though.
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Old 23rd December 2017, 07:44 PM   #27
indra1 is offline indra1  Indonesia
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In case of interest. There is this epay specspecialty in Texas claiming to have some 1800 pcs in stock of Harris IRFP9141 (item id 321945025104) for $5 and offer quantity discount. Similar enough spec to IRFP9140 except for 80V Vdsmax which should pose no problem for an Aleph build. Just search for IRFP9141. I also still see a few epay seller offer metal can TO3 Harris IRF9140.
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Old 16th April 2018, 04:54 AM   #28
sarathssca is offline sarathssca  India
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Hi .. any updates on BF862 based inverted aleph j ??
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