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Author Topic: NOR Gates  (Read 10045 times)

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Grumpy

What are you trying to build, is it a ring counter for the tetra, if so i built this some years ago and had it running, i used 2 74HCT74 D types and 1 Nor gate, i can dig the circuit out if you wish.


For pulse width and phase delay i used 2 monostable for each Channel, i went on to design my digital delay monostable using a 1nS delay line chip which formed the basis of my Explosion in the wire experiments.

Quote
If I am using 3 of the 5 inputs, what do I do with the other 2?
Just connect them to one of the used inputs

When building the monostable be careful, some chip manufacturers have slow and bad timing abilities, there are some monos that can work down to 80nS, to be honest it was a long time ago i cannot remember which chip or manufacturer i finally chose, it worked ok because all 4 channels had a mono board and therefore any slow responses were evened out across all 4 boards which just left the phase adjustment to the required firing alignment, the minimum pulse width was restricted to the datasheet specs though, which is why i went on to build the digital mono's that were adjustable in nS increments.

The problem with the Tetra is we do not know how fast or at what frequency it should be running at and because at the time people were speculating it should be running at 60MHz i gave up due to the complexities of running it at such speed, from tests you would never be able to run the brooks coils at such a high speed anyway they would appear as capacitive loads due to the 1.8km of wire i used for each coil.

One thing though i did pickup fast switching transients across the output doughnut coil and at the time i did not realize any significance to that.
« Last Edit: 2013-12-31, 13:31:59 by Peterae »
   

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Thanks Peter.  I am looking to drive both the tetra and the 6 coil ring.

Since I am using avalanche transistors, the pulse width is set by the delay line, which also shuts the switch off, so I want to keep this.

I have a Johnson counter that worked a long time ago. I'm just getting back into it and forgot a lot.

EDIT:
What voltage level did you use?
   

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Hi G

The tetra was early days for my experimenting, i used lowish voltage and never got it running at high voltage.

You may have trouble with Avalanche, i never got mine working over 1khz pulse repetition, it would sure be interesting if you manage to give it a good try.

Yes i also build a Spheric MK2 using a Johnson counter, This attached circuit has not come out very good it you want a close up let me know and i will try getting it a bit better.  O0
   

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Thanks I may try the Johnson again.

My problem with the avalanche stacks has been reliably triggering them using a ferrite bead as a trigger transformer per the work by Baker. 

I may try using the overvoltage method as it will trigger better that way, but I have to devise a good way to apply the voltage and stay isolated from it going through the trigger circuit.

They will easily free-run at high repetition rates.
   

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Sounds good G

Good luck with your build, it's always good to have a plan  O0
   
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