| bitrex <user@example.net>: Apr 22 12:00AM -0400 On 4/21/2021 8:41 PM, John Robertson wrote: > Where's the fun in that? As I said, I know I can still get new tubes. > The problem is the system doesn't work well... > John ;-#)# There's this patent from '66 that describes a solid-state thyratron replacement: <https://patentimages.storage.googleapis.com/42/6a/0d/6e35c415a3f0e0/US3293449.pdf> It uses a couple of SCRs. It's to replace high-power thyratrons but I don't see why it couldn't be scaled-down. |
| bitrex <user@example.net>: Apr 22 12:04AM -0400 On 4/21/2021 8:41 PM, John Robertson wrote: > Where's the fun in that? As I said, I know I can still get new tubes. > The problem is the system doesn't work well... > John ;-#)# What's a "Wall-o-Matic"? |
| bitrex <user@example.net>: Apr 22 01:07AM -0400 On 4/21/2021 3:47 PM, John Robertson wrote: > This controlled a solenoid at around 24VAC or regulated (0A2 = -150VDC) > power supply for the tormat write-in and readout circuits. > John :-#)# I can't find a solid reference on what the gas in the 2D21 is, anyway. Only few references from the time period I can find don't agree, one paper says it's hydrogen: <https://books.google.com/books?id=IdB5E4STz5kC&lpg=RA5-PA37&ots=T6ZN06aJWy&dq=hydrogen%20in%202d21&pg=RA5-PA37#v=onepage&q=hydrogen%20in%202d21&f=false> Another says it's xenon: <http://phylab.fudan.edu.cn/lib/exe/fetch.php?media=exp:ajp000701.pdf> |
| bitrex <user@example.net>: Apr 22 01:14AM -0400 On 4/22/2021 1:07 AM, bitrex wrote: > <https://books.google.com/books?id=IdB5E4STz5kC&lpg=RA5-PA37&ots=T6ZN06aJWy&dq=hydrogen%20in%202d21&pg=RA5-PA37#v=onepage&q=hydrogen%20in%202d21&f=false> > Another says it's xenon: > <http://phylab.fudan.edu.cn/lib/exe/fetch.php?media=exp:ajp000701.pdf> Maybe a mixture of stuff. |
| bitrex <user@example.net>: Apr 22 02:43AM -0400 On 4/22/2021 1:07 AM, bitrex wrote: > <https://books.google.com/books?id=IdB5E4STz5kC&lpg=RA5-PA37&ots=T6ZN06aJWy&dq=hydrogen%20in%202d21&pg=RA5-PA37#v=onepage&q=hydrogen%20in%202d21&f=false> > Another says it's xenon: > <http://phylab.fudan.edu.cn/lib/exe/fetch.php?media=exp:ajp000701.pdf> I think it must be xenon, the first one is just wrong |
| DecadentLinuxUserNumeroUno@decadence.org: Apr 22 08:04AM bitrex <user@example.net> wrote in >> In case you missed it, he was backing me up. > I would hope so! You're team lead, now No... According to the LarkinPunk, I am a mere "technician" who "hates the magic" of engineers. |
| piglet <erichpwagner@hotmail.com>: Apr 22 10:04AM +0100 On 22/04/2021 5:00 am, bitrex wrote: > <https://patentimages.storage.googleapis.com/42/6a/0d/6e35c415a3f0e0/US3293449.pdf> > It uses a couple of SCRs. It's to replace high-power thyratrons but I > don't see why it couldn't be scaled-down. Thanks Bitrex, that patent even mentions a tunnel diode and UJT which are now very exotic devices. The struggle was to emulate the high impedance thyratron grid. It seems to me (I have never seen a thyratron) that a modern depletion mode mosfet would make a good front-end to a SCR in that a negative grid bias is required to keep the device non-conducting (if I understand thyratrons correctly). Here is a conceptual sketch: <https://www.dropbox.com/s/al1b8hj07i7jfpq/SED_Thyratron_Idea.pdf?dl=0> Possible fets could be BSS126 or LND150 and SCR with sensitive gates X0402NF or BT149G. piglet |
| bitrex <user@example.net>: Apr 22 09:21AM -0400 On 4/22/2021 5:04 AM, piglet wrote: > that a modern depletion mode mosfet would make a good front-end to a SCR > in that a negative grid bias is required to keep the device > non-conducting (if I understand thyratrons correctly). Well Fig 2 in the patent doesn't look like it requires anything exotic, the exotics look to be included in the "further embodiment of the invention" > Possible fets could be BSS126 or LND150 and SCR with sensitive gates > X0402NF or BT149G. > piglet Yeah, depletion mode MOSFET seems a plausible modern take on it. Only thing is a real gas thyratron the anode current is controlled by the control grid current when it's in the low impedance ionized state. In many switching applications though I expect this doesn't matter too much it doesn't matter what the impedance is in that state exactly, just so long as it's low enough to reliably fire the relay or whatever. And there doesn't need to be an analog to the screen grid, when the tube is used like a switch to ground it's usually connected to the cathode and just prevents the thyratron from firing until the positive-going pulse on the control grid is seen. You can see in a 2D21 a box-like structure surrounding all the other electrodes and I believe that whole structure is connected to the screen grid pin. |
| bitrex <user@example.net>: Apr 22 09:35AM -0400 >> I would hope so! You're team lead, now > No... According to the LarkinPunk, I am a mere "technician" who > "hates the magic" of engineers. Sounds like you have something to prove. Sometimes when I'm helping the little ol' lady in the library do her taxes some kid shows up with something to prove too and is like "No dummy you're doing that all wrong" and then I say "Okay.." and hand the job off directly to him, let him spend the next two hours with her while I go about my day. I'm not going to fight him on it he is the white-knight expert who has appeared in our time of most need. And it makes Ethel very happy! But that's interesting about the line voltage it seems to be a common misconception and 1954 was a long time before I was born. In any case my thoughts on the 2D21-dying issue have changed it's not hydrogen-filled it's probably primarily xenon. Hydrogen-filled thyratrons are more temperature-sensitive to both the temperature of the heater and temperature of the glass if they're too hot all the hydrogen tries to run away or react with the hot cathode. Obviously xenon won't react with the internal elements or the getter but it can still be absorbed by the glass or escape where the pins come in. So I still think the reason they end up malfunctioning in service is that the gas is escaping or being absorbed by the glass and reducing the operating temperature of the cathode may extend their life. |
| bitrex <user@example.net>: Apr 22 09:48AM -0400 On 4/22/2021 9:21 AM, bitrex wrote: > Well Fig 2 in the patent doesn't look like it requires anything exotic, > the exotics look to be included in the "further embodiment of the > invention" Oh okay I see what you're saying, instead of using a high-impedance SCR as the first element in a two-SCR pair there are better devices to solve that "struggle" of the inventor, now. |
| jlarkin@highlandsniptechnology.com: Apr 22 09:14AM -0700 On Wed, 21 Apr 2021 12:44:37 -0700, John Robertson <spam@flippers.com> wrote: >Control Center: >https://www.flippers.com/pdfs/Seeburg_V200_Pg_5113-5143_B&W.pdf >Relevant schematic is on page 5128 (pg 16 or the PDF). Yikes. The tube pins all go to off-page connectors, so it's not easy. -- John Larkin Highland Technology, Inc The best designs are necessarily accidental. |
| amdx <amdx@knology.net>: Apr 22 11:40AM -0500 -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
| HW <none@no.no>: Apr 22 02:53PM +0200 On Wed, 21 Apr 2021 01:05:27 -0000 (UTC), bob prohaska >What about "oscilloscopes" based on USB sound cards? From what I understand, most people who have tried both, prefer a standalone scope over a PC based one. >in the $200-500 range. You can get a very nice, brand new, hobby scope for that kind of money. The Rigol DS1054Z seems to be available for around $450. That is a four-channel, 50 MHz scope. It can easily be hacked for 100 MHz bandwidth. |
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