Yes, of course. Thank you Il giorno martedì 28 novembre 2023 alle 18:15:39 UTC Instrument Resources of America ha scritto:
> Be careful not to burn a spot on the screens phosphor coating. High > intensity, coupled with length of time in one spot is what determines if a > burn occurs. > > Ira. > > > On 11/28/2023 9:05 AM, 'Grahame' via neonixie-l wrote: > > I would guess that the bright spot is where the beam rests after drawing > the face and is waiting for the next refresh trigger. > > My own scope clock draws each face once every 20mS (16.66mS in 60Hz land) > synchronised to the mains. If a particular face takes, say, 8mS to draw > then the beam is parked somewhere and left blanked for the remaining 12mS > (in this example) waiting for the next face refresh trigger. So if the beam > is left on for the waiting period then it will appear as a very bright spot > at the parked position. You'd have to investigate the software you're using > for what triggers the face drawing and what happens in the waiting period. > > Grahame > On 27/11/2023 22:50, Max DN wrote: > > I'm attaching the voltage divider that I am using and the one that I'm > going to try using values calculated assuming 0.5mA current draw (which I > understand makes sense for this CRT). > > Sharing this useful website to calculate resistor values using parameters > from the datasheet, it is starting to make sense now! > > https://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1946/12/page45/index.html > > Blanking pin currently disconnected (still waiting for an optocoupler). I > wonder whether that will fix the bright spot (of course it will fix the > smears on the display). > > @ gregebert - I may find this latest update useful > > Il giorno lunedì 27 novembre 2023 alle 09:28:02 UTC Max Di Noi ha scritto: > >> Ok, I managed to make some improvements by changing some resistors on the >> voltage divider, I'll post my new layout later. >> >> Much better now, although I need to better understand how to calculate >> resistor values as at the moment I don't know current draws by each crt >> pin. >> >> I get a very bright spot on the clock image, I don't know if that's >> because I have not connected the blanking circuitry yet or overvoltage on >> A1 (I'm waiting for an optocoupler, hopefully it arrives this week). >> >> Picture attached. Getting there. >> >> >> -------- Original message -------- >> From: 'Grahame' via neonixie-l <neoni...@googlegroups.com> >> Date: 26/11/2023 11:21 (GMT+00:00) >> To: neoni...@googlegroups.com >> Subject: Re: [neonixie-l] Scope Clock with 3LO1i >> >> Hi >> >> £55 is expensive - you should be able to get them for £30. >> >> Have you tied the deflection plates to A2 for testing purposes or left >> them floating? They should be tied to A2. >> >> Can you turn the brightness pot down to fully extinguish the dot? If not >> you need to be able to. >> >> Grahame >> On 25/11/2023 18:28, Max DN wrote: >> >> @Grahame >> Thanks for the suggestion. I didn't know about CV2302 DH3-91, I see >> Langrex is selling it for £55 on eBay. >> >> Yes, my voltages were off. I have made some changes: >> Cathode is now -350V to ground >> A1 is +30V above cathode >> A2 is +150V above ground, that is +500V above cathode >> I'm having some problems with Grid voltage, I'm guessing... >> >> >> @gregebert >> This is the pinout I'm using: >> Pins 1-14 heater >> Pin 2 Cathode >> Pin 3 Grid G1 >> Pin 4 A1 (focus anode) >> Pin 5 n/c >> Pin 6 Grid G2 >> Pin 7 X1 >> Pin 8 X2 >> Pin 9 A2 (acceleration anode) >> Pin 10 Y1 >> Pin 11 Y2 >> Pin 12 Grid G3 >> Pin 13 n/c >> Pins 3-6-12 are all internally connected, other than on mine 3 is no >> longer soldered on the grid. >> >> Pin 3 or 6 or 12 (Grid) is connected to -525V (that's 40V above -485V >> negative voltage doubler in Cathode Corner's schematic), still not good >> (pic attached). I connected a few resistors in series 500k, then 1M to >> bring voltage down up to -250V, with not much difference. So it's clear I >> don't understand how to connect the Grid pin!! >> >> I did find a schematic here (suggests to reduce max negative voltage rail >> to -300V): >> https://www.catahoulatech.com/index.php?product=KIT-0001 >> >> https://www.catahoulatech.com/products/KIT-0001/OscilloscopeCrtDriverData.pdf >> >> I also find something else that is exactly what I'm trying to do. It's >> using different POTs and +350V vs -350V (whereas I'm using +250V and >> -485V)... Schematic attached. >> >> >> Il giorno sabato 25 novembre 2023 alle 10:07:25 UTC Grahame ha scritto: >> >>> Hi Max >>> >>> https://threeneurons.files.wordpress.com/2015/05/3lo1i.pdf >>> >>> gives the normal operation acceleration anode A2 voltage as 500V (WRT >>> cathode) and the focus anode A1 as 0 to 50V. Your voltages are higher, >>> especially the focus anode voltage. Hence the green splat rather than a dot. >>> >>> My experience with this tube and the 6LO1i which is the slightly larger >>> rectangular version is very poor. The phosphor literally turned grey, then >>> black and the light emission faded over a couple of months in use. It >>> wasn't that the phosphor burned with the image but the phosphor greyed >>> uniformly. Most odd. Might have it been a bad batch of tubes? IIRC someone >>> else has seen this effect. >>> >>> If you want a small tube then look out for a 1CP1 or DH3-91 or CV2302 >>> would be my suggestion. >>> >>> Grahame >>> On 24/11/2023 22:49, Max DN wrote: >>> >>> Hello, >>> >>> I managed to successfully build a scope clock almost entirely based on >>> Cathode Corner design using CRT 3RP1A. >>> >>> I happen to have a 3LO1i (I know it only lasts for 1000 hours...) and I >>> tried to modify the voltage doublers to use my circuit with this CRT but >>> I'm not too sure about the correct voltages. At the moment I have: >>> Grid: -480V; HTR2: -380V; HTR1: -384V; HTR1-HRT2: 6.3VDC; CATH: -384V; >>> A1: -248V; A2: +200V >>> >>> However I cannot get a small green dot, only a wide green shade, picture >>> attached. >>> I'm sure I'm doing something wrong with the voltage divider. Any >>> suggestions please? >>> >>> Thank you, >>> Max >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "neonixie-l" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to neonixie-l+...@googlegroups.com. >>> To view this discussion on the web, visit >>> https://groups.google.com/d/msgid/neonixie-l/669f964f-9fec-4cb1-8a03-f06a1749131en%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/neonixie-l/669f964f-9fec-4cb1-8a03-f06a1749131en%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >>> -- >> You received this message because you are subscribed to the Google Groups >> "neonixie-l" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to neonixie-l+...@googlegroups.com. >> To view this discussion on the web, visit >> https://groups.google.com/d/msgid/neonixie-l/3e5e58ba-b3f9-41ae-95c0-2fd4ac9291c4n%40googlegroups.com >> >> <https://groups.google.com/d/msgid/neonixie-l/3e5e58ba-b3f9-41ae-95c0-2fd4ac9291c4n%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> >> -- >> You received this message because you are subscribed to the Google Groups >> "neonixie-l" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to neonixie-l+...@googlegroups.com. >> To view this discussion on the web, visit >> https://groups.google.com/d/msgid/neonixie-l/05e95c29-8bc5-4b6f-abc2-c211936daedd%40googlemail.com >> >> <https://groups.google.com/d/msgid/neonixie-l/05e95c29-8bc5-4b6f-abc2-c211936daedd%40googlemail.com?utm_medium=email&utm_source=footer> >> . >> > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to neonixie-l+...@googlegroups.com. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/95489733-8556-4c02-8828-033acd00df03n%40googlegroups.com > > <https://groups.google.com/d/msgid/neonixie-l/95489733-8556-4c02-8828-033acd00df03n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to neonixie-l+...@googlegroups.com. > > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/d014913b-2639-4609-ac27-a011d8570946%40googlemail.com > > <https://groups.google.com/d/msgid/neonixie-l/d014913b-2639-4609-ac27-a011d8570946%40googlemail.com?utm_medium=email&utm_source=footer> > . > > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. 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