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Resource depletion mode
Posted: Sun Nov 11, 2018 7:05 pm
by cherler
So I've been screwing around with JFET cascodes for a hot minute, but getting through hole JFETs is a pain in the ass now. I'm cool with SMD, but it seems like it might be time to consider alternatives anyway. I was thinking about depletion mode MOSFETs as a potential alternative. They wouldn't be a drop in replacement, but maybe they can get there being depletion mode and having low/no gate current? Have ya'll used anything more common/actually produced in place of JFETs?
Re: Resource depletion mode
Posted: Sun Nov 11, 2018 8:04 pm
by BetterOffShred
Yeah it sucks man. I've bought a huge pile of J113s and those are my go to's now. The SMT 201s are unobtanium too, so yeah I'm in the same boat. I got a shit pot of 2N7000s and BS170s.. which are supposed to be interchangeable (reversed pinout) but I swear the 7000s sound better.
https://www.mouser.com/ProductDetail/Mi ... YUxMHwQ%3d
This is a good one, and I believe it's what Spaceman uses in the Saturn 5..
I'd like to see what some of the dudes who are good at this stuff think.
Re: Resource depletion mode
Posted: Sun Nov 11, 2018 8:08 pm
by cherler
I was just looking at that one! I think I'm just gonna order a bunch and give it a go.
Re: Resource depletion mode
Posted: Sun Nov 11, 2018 8:14 pm
by BetterOffShred
Yeah I think I ordered 20 or something a while back, I'll have to dig them up
Re: Resource depletion mode
Posted: Sun Nov 11, 2018 9:05 pm
by crochambeau
I've been happy using 2N7000 when I want to curtail any current feeding into that stage, but I have not used them as switches.
Re: Resource depletion mode
Posted: Sun Nov 11, 2018 9:32 pm
by cherler
I suppose there's really no reason I'd have to go depletion mode, I just figured it was a good way to preserve as much similarity as possible. The circuit I'm working on does a lot of wacky oscillation and sub octave stuff, so I'm not sure how much I'm riding on any one particular property of the 2n5457's I'm using.
Re: Resource depletion mode
Posted: Sun Nov 11, 2018 9:58 pm
by BetterOffShred
You should let us peep that schematic..

Re: Resource depletion mode
Posted: Sun Nov 11, 2018 10:01 pm
by AZX309
i mean you can always try things out. i have an all mosfet big muff right now and it great
in terms of depletion mode, People smarter then me are into/ exploring them. i know one of the electrofoods guys has an V4 simulation using depletion mode. they are next of my list of things to explore after shitty op-amps.
Re: Resource depletion mode
Posted: Sun Nov 11, 2018 10:14 pm
by BetterOffShred
AZX309 wrote:i mean you can always try things out. i have an all mosfet big muff right now and it great
in terms of depletion mode, People smarter then me are into/ exploring them. i know one of the electrofoods guys has an V4 simulation using depletion mode. they are next of my list of things to explore after shitty op-amps.
Yeah I have the all mosfet big muff schematic, looks dece. I like mosfets in most things
Re: Resource depletion mode
Posted: Mon Nov 12, 2018 1:46 am
by eatyourguitar
I am really surprised that the TO-92 is available and the SMD version is not. when this was end of life 5 years ago everyone was saying two things, "buy them NOW", and "don't worry, we can just buy SMD 201 forever".
Stock Status: 84959
Price: $0.33
https://www.utsource.net/itm/p/1243065.html
meanwhile mouser is taking pre-orders till ON semi takes the bait. it could be a while and might never happen at all. some vendors for military applications have rules that they can not buy from UTsource or china so they just stack up orders on mouser.
Re: Resource depletion mode
Posted: Mon Nov 12, 2018 9:01 am
by cherler
No shit, that is by far the cheapest J201 I've seen in a long time.
Re: Resource depletion mode
Posted: Mon Nov 12, 2018 9:16 pm
by AZX309
holy shit that is cheep.
I ordered some MMBF201's for shits and giggles and was waitlisted for three months, i can only imagine its gutwenchlingly frustrating to have to wait for actual mass production use.