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DIY Stompboxes => Building your own stompbox => Topic started by: electrosonic on July 20, 2013, 01:45:13 PM

Title: J112 for gain stage
Post by: electrosonic on July 20, 2013, 01:45:13 PM
I noticed these are cheap at newark, less than $0.08 each. I see merlin uses them for signal switching in some of his designs. Any reason they couldn't be used for a gain stage?

Andrew.

This is the link to the Canadian site.  http://canada.newark.com/on-semiconductor/j112g/n-channel-jfet-chopper-35v-to/dp/26K3591?MER=PPSO_N_C_EverywhereElse_None (http://canada.newark.com/on-semiconductor/j112g/n-channel-jfet-chopper-35v-to/dp/26K3591?MER=PPSO_N_C_EverywhereElse_None)

The newark part# is 26K3591
Title: Re: J112 for gain stage
Post by: Thecomedian on July 20, 2013, 06:56:13 PM
they could be subpar for amplification. Their design is pretty good for switching.

http://www.onsemi.com/pub_link/Collateral/J111-D.PDF

http://www.physicsforums.com/showthread.php?t=301905

If any amplification it performs isn't very linear, it might have a good "tube sounding overdrive" quality to it. It's not too expensive to buy a few and try it out, swap other Jfet transistors intended for amplification in and out and have a quick "by-ear" test.
Title: Re: J112 for gain stage
Post by: gritz on July 20, 2013, 07:42:55 PM
^^^what Thecomedian said^^^

I had some leftover J117 (also a "switching fet, but "P" type) and had a go at making a multi stage distortion thinger with them. Whatever I did it sounded rather harsh and fizzy (with the caveat that I'm not the world's foremost authority on fet preamps...)  I mused that it was possibly something to do with their very low "on" resistance making them clip very square, or somesuch.

However, nothing ventured, nothing gained. At that price it's worth grabbing a few and trying some stuff. It's possible that if you use them in a circuit that doesn't explicitly clip hard (like a treble booster) then they may work well. They may also be ok as source follower unity gain buffers and so could replace the rather finite-in-supply J201 in that role. It's worth a try.
Title: Re: J112 for gain stage
Post by: Thecomedian on July 21, 2013, 10:15:37 PM
I'll have to try that, too, someday Gritz. They are non-linear for transistor devices, so instead of multi-stage, a single stage with good biasing MIGHT sound useable.
Title: Re: J112 for gain stage
Post by: duck_arse on July 22, 2013, 11:39:47 AM
they look like a good choice for shunt-work  in tremolos and slow gears and phasers etc. and they will probly drop straight into a 2n5457 circuit. probly. at 0.08c each, you can't go wrong.