Tunnel Diode flipflop

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Tunnel Diode flipflop

Postby Starfire » Tue Apr 23, 2013 3:55 pm

Latest attempt at a tunnel diode flipflop with two tunnel diodes driving each other.

The idea is when one diode oscillates the coil will have one end in opposite phase to the other so that the other diode will flip opposite. The coil is between diodes and other coils are chokes going to a central choke in the feed line. Every thing in very small and at this stage frequency does not matter - just get it going and hope it quantum switches.

If it quantum switches the rise and fall times should be very fast - f/sec ??

8-)
DSCN0147[1].JPG
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Re: Tunnel Diode flipflop

Postby Doug Coulter » Tue Apr 23, 2013 8:55 pm

I wish you the best of luck on this. As far as I understand these, this *should* work, and work well. However, up at those speeds, the tiniest detail of layout - the stray L's and C's and how they couple, are of extreme importance. So, like with my fusor, I guess you spend more on instrumentation than the thing itself! Or you wind up hunting in the dark.

This would be a great example to bring up when people complain "why is this so expensive, it's only a couple bucks worth of parts?". Yeah, but making it work with only a couple bucks of parts IS the key - and worth paying someone to work out, and that someone needs the right gear and the right training. If it was simple, any fool could do it.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Tunnel Diode flipflop

Postby Starfire » Wed Apr 24, 2013 7:03 pm

Theory says it should be possible to achieve better than an attosecond (300 attoseconds is the time taken for the Electron to jump an Atom ) - This is because it quantum tunnels and electrons get across the diode in an instant taking no time. Perhaps a window to the forth dimension :lol:

But now the bad news - I can't get the thing to work - I may have used too much heat as the diodes don't take much. Oh well, more diodes, low temp solder this time and try again - the fun is in the trying, success makes one arrogant ;)
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Re: Tunnel Diode flipflop

Postby johnf » Fri Apr 26, 2013 12:16 am

John
you of all people should know the pnpn junction is very lightly doped to make these
a bit of heat will make it into a pn junction I think this is why Tek put these in sockets in the 465 scope trigger circuit

used to have four of them wrapped in foil but I haven't seen them for quite a few years
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Re: Tunnel Diode flipflop

Postby Doug Coulter » Mon Apr 29, 2013 5:16 pm

I strongly suspect Mr Futter is right - I also would try playing with those two side by side inductors. That setup just doesn't seem exactly right to me, but that's a guess. You'd mainly just get capacitive coupling between them as shown, and maybe not in the right phase to make it "go". The inductors look on the large side for your speeds (~~~100 mhz type coils is what I see there, tops). Their self-resonance might also be an inhibition to correct operation.
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Re: Tunnel Diode flipflop

Postby Starfire » Thu May 02, 2013 6:38 pm

John
It is the kid in me being impatient :) I had used tunnels before with solder but many years ago so I may need to relearn.

Doug
the main inductor is one turn fine between the diodes but is very hard to see in this pic (need to enlarge) - freq is not important - just to get osc on the curve.
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Re: Tunnel Diode flipflop

Postby Doug Coulter » Sat Jun 08, 2013 5:51 pm

Ah, I didn't see that tiny turn. I hope you didn't melt your diodes - I'm usually careful with that sort of thing, since they are a bit scarce. Can you rig up a tester that sees if you can make one oscillate at a time?

I believe I recall Tektronix used something like what you're doing at some point to enhance rise times/reduce time jitter. I'd have to go search, or ask Joe Sousa to find out.
I know they did some trick back in the day of tubes to get ghz sampling, in effect, for repetitive waveforms, and it used tunnel diodes.
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