indeed sorry I didnt mean that. however it does some very strange things. amplifying signal from your fingers in just a voltage follower arrangement sometimes.
yeah hanging as in locking high and slowly returning, I have noticed it for years this and never really questioned it. very strange. just set up a voltage follower circuit, and pop your finger on the input a few times and see what happens. sometimes it will lock high and slowly fall
niceee!!! what you gunna do with those???
Well, everyone needs one I think but these pins are for a couple of people I know. Spreading the word etc 
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oh was it a mistake to order 3?? I can try and sort it out tomorrow morning if you wanted just the 1??? aaah cool man thanks a lot everyone needs a “90’s toy” on their backpack hahaha
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Oh, not at all, that was very much intentional. Maybe a mistake to order only three (but let’s start with this, I’ll get some more next time).
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The gates have a tiny bit of capacitance, and since they also have very high impedance (they’re basically reverse-biased diodes, more or less), once you charge things up it makes sense that it’ll stay that way for quite some time (time constant is R×C for tiny C but very large R).
I’m still gonna build yours! Must have all the kosmos. Also is it wrong to want a second splashback?
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I like to view it as, HASL is $15 less. Gold plate is standard for end products. HASL is likely to corrode over time. I don’t know if that’s a problem for art and panels though, or only for soldering after storage.
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Don’t do this:
Do this (from the tech note I posted just a few posts below the bad design 
; the right opamp is unused):
This works if you have a split supply; for single supply designs you have to construct a mid-supply rail (see the tech note for how to do that).
(also, as noted elsewhere, there’s no noticeable difference between TL074 and TL084 so if you have the former, you don’t need to buy the latter. But whichever you use, don’t leave the unused opamps hanging…)
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Ah, I knew I had to do something to keep the unused op amps from being a nuisance. Thanks for this very handy summary. I’ll be playing with my tl074 pdips very soon (I’ve been saying that for a week but life keeps getting in the way.)
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After a quick trip to Anchor Electronics for some DPDT on-off-on switches, I used my last stash of box jacks and finished the switched multiple. Switch seven somehow doesn’t turn off the right side in any of the three positions, but otherwise looking good. I deliberately used the same color LEDs on both sides.
The dual multiple is done except for the jacks.
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Won’t turn off? What the heck lol
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Sorry for the delay CTorp the switch multi is rad I’d love one of those! Let me know $ when you order, thanks!
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You may have explained this elsewhere. Why the feedback loop and not ground the minus input as well?
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The inputs aren’t perfect, and there’s always a tiny input offset (for TL07x it’s couple of mV) so if you just connect both inputs to the same voltage with no feedback, it’ll end up amplifying it’s own offset.
Wiring it up as a voltage buffer avoids that; the negative feedback keeps it stable, and using 0 V means that both inputs and outputs stay within the “common mode” limits.
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So would you expect it to potentially oscillate if both inputs were grounded ( no feedback loop ) or what would be the draw back of it amplifying it’s own offset?
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I think it falls under “undefined behaviour”; probably more “drawing current doing nothing” than oscillating wildly, but if you’re unlucky it may do weird things.
(also the output pin is next to the negative input pin in the standard dual and quad pinouts so there’s not much of an excuse for not doing the right thing ).
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But if the risks of oscillations are limited one could argue the positive input is always next to the negative so the GND is close as well. Ok, I get the picture.
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