Have you tried the circuit in the J.B Dance book below? Here they use a center tapped transformer and also a much lower value capacitor, only 33nF versus 250nF in your circuit - I've only evere seen 33nF used in real instruments using these indicators.
Quite a few of the Z550M/ZM1050 are broken internally, I have a box of them, and that seems to be due to the welding of the internal parts coming loose when shaken or hit hard (the same problem exists with the B9012/NL9012 tubes - I have a few broken ones of those too with internal pieces that have come loose) - sometimes you can hear these loose pieces if you shake the tube very carefully close to your ear. What usually happens is that a rather large round center piece comes loose and in the worst case shortens some of the electrodes but usually only makes it hard or impossible to get all digits to light up poperly and some of them trigger easier than others due to the distances between electrodes are differing, shaking the tube a little moves that effect around so other digits will start to work and vice versa. /Martin [image: JBDance-Z550M.JPG] On Thursday, 11 February 2021 at 06:02:24 UTC+1 gregebert wrote: > If you have an isolation transformer, can you put a scope on the cathode > line to verify the ripple is not excessive ? Rk and Ck create an RC filter > around 77Hz, and the line is 50-60Hz, so there could be some ripple. > > On Wednesday, February 10, 2021 at 8:26:51 PM UTC-8 [email protected] > wrote: > >> I tried varying it with absolutely no effect. It runs perfectly at 5v >> with the capacitor moved to the other side of the resistor. However I was >> clocking slowly. It may not run at spec speed. I seem to remember reading >> of using 5 to 8 volts for the logic. >> The data sheet shows the following which I'm inclined to believe. I will >> try Ck directly on the pins tomorrow. Someone must have tried this circuit. >> [image: 8453 Cct.JPG] >> >> On Wed, Feb 10, 2021 at 11:12 PM gregebert <[email protected]> wrote: >> >>> I suspect the differential voltage between lit vs non-lit numerals is >>> too low. The CMOS device is basically driving grids to determine which >>> cathode will be illuminated. I've seen similar behavior with an A-101 >>> dekatron. What voltage are you using for VDD ? Is it 8V as indicated on the >>> schematic, or a more-conventional 5V ? >>> >>> On Wednesday, February 10, 2021 at 7:22:25 PM UTC-8 [email protected] >>> wrote: >>> >>>> I think you are wrong. The literature explains this tube is designed to >>>> be driven by 5v logic and it does work. The steering electrodes are close >>>> to the Anode voltage which is grounded and only 5v pulses (square waves) >>>> are needed. Note all the cathodes are connected together internally. >>>> I got to thinking about the C1 position. The data sheet shows it per my >>>> schematic and I can't believe they made that mistake several times >>>> including the hand drawn notes of the designer. I think maybe I needed to >>>> have C1 directly on the socket pins and will try that tomorrow. >>>> Thanks for your interest though but you are thinking Nixie Tubes, this >>>> is a special tube with steering electrodes.. >>>> >>>> >>>> On Wed, Feb 10, 2021 at 9:42 PM chuckrr <[email protected]> wrote: >>>> >>>>> That schematic is so wrong in so many ways. You need high voltage >>>>> transistors operating the tube cathodes. >>>>> >>>>> You need high resistance drving the transistor bases. You need a >>>>> buffer such as 4049 or 4050 driving the >>>>> >>>>> resistor, which in turn drives the transistor base. Only then would I >>>>> dare to use the 4028....to operate the buffer, which in turn operates the >>>>> >>>>> transistor base via appropriate high resistance. That is the only >>>>> sure fire way I know of to attain noise-free performance from CMOS logic >>>>> >>>>> driving cold cathode tubes. That schematic there is a noisy deal. >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> ---- Original Message ---- >>>>> From: "peter bunge" <[email protected]> >>>>> Sent: 2/10/2021 8:15:21 PM >>>>> To: "neonixie-l" <[email protected]> >>>>> Subject: [neonixie-l] 8453/Z550M erratic >>>>> >>>>> Using the schematic from the data sheet >>>>> [image: 8453 Circuit.jpg] >>>>> This works with the count moving around but other numbers flash >>>>> erratically, especially close to the number that is supposed to be lit. >>>>> *When I moved the bottom of C1 to the other side of R1 it works >>>>> perfectly. It is rock steady and does not care about line voltage or the >>>>> 5v supply (shown above as 8v but used at 5v)* >>>>> If this is an error it is continued through all the documentation and >>>>> is consistent. Changing the value of C1 up and down by 10 had little >>>>> effect >>>>> but a smaller C1 helps a bit. My Rst are all directly on the socket pins >>>>> and the wires are all about 5 inches long. >>>>> I have varied the line voltage with little effect. >>>>> Any suggestions??? >>>>> >>>>> -- >>>>> 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 [email protected]. >>>>> To view this discussion on the web, visit >>>>> https://groups.google.com/d/msgid/neonixie-l/b996ef0b-edbb-4c77-8ec1-57255dd58a82n%40googlegroups.com >>>>> >>>>> <https://groups.google.com/d/msgid/neonixie-l/b996ef0b-edbb-4c77-8ec1-57255dd58a82n%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 [email protected]. >>>>> >>>> To view this discussion on the web, visit >>>>> https://groups.google.com/d/msgid/neonixie-l/202102101842701.SM05295%40ADT-IM1 >>>>> >>>>> <https://groups.google.com/d/msgid/neonixie-l/202102101842701.SM05295%40ADT-IM1?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 [email protected]. >>> >> To view this discussion on the web, visit >>> https://groups.google.com/d/msgid/neonixie-l/9543e23e-ebb0-46e7-8624-ddcf4a843667n%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/neonixie-l/9543e23e-ebb0-46e7-8624-ddcf4a843667n%40googlegroups.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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