I meant dekatron in my last reply to gregebert. I have 3 of these tubes, all apparently new (NOS). Per your suggestion I tried the other two. One is almost perfect but flashes the 2 a bit when 8 is selected. The third is perfect unless I hold the tube in my fingers by the glass where I get lots of random flashing. Remember that the really bad one works perfectly with the capacitor moved as I mentioned. I don't know if touching the glass affects it. More later, I will be away this morning. Peter.
On Thu, Feb 11, 2021 at 2:10 AM Dekatron42 <[email protected]> wrote: > 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. > 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/7085da7d-27dd-46f3-9bba-9e2d369dcc4fn%40googlegroups.com > <https://groups.google.com/d/msgid/neonixie-l/7085da7d-27dd-46f3-9bba-9e2d369dcc4fn%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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