[neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

Nick, Martin, thanks for the read! W dniu wtorek, 23 stycznia 2018 00:56:25 UTC+1 użytkownik gregebert napisał: > > There is 1 other thing that could be happening, and although it *wont* > cause ghosting, it *will* add confusion from the measured waveforms: If > the PNP driver turns-on momentari

[neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

There is 1 other thing that could be happening, and although it *wont* cause ghosting, it *will* add confusion from the measured waveforms: If the PNP driver turns-on momentarily, for a few usec, it will charge the parasitic capacitance (scope probe AND nixie tube). If the duration is short eno

[neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

Nothing special - I used Adobe Acrobat Pro DC (Version: 2018.009.20050) - selected *Edit PDF* then *Enhance Scans,* then from the *Enhance *dropdown, select *Scanned Document.* Then make sure *All Pages* and *Recognize Text* are selected, before pressing the *Enhance* button. The metadata is se

[neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

Ok, I have Acrobat Pro but I never get the results that I want when I try to do the same procedure. What, and how, do you do in the last three steps "optimise them, OCR the result and to set the metadata.", maybe I am doing something wrong. the problem I stumble upon the most is that the OCR is

[neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

Sure - I have a copy of Adobe Acrobat DC and used that - it allows you to assemble images into a PDF, optimise them, OCR the result and to set the metadata. Nick -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and

[neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

Nice! Can you share how you made the PDF? /Martin On Sunday, 21 January 2018 08:32:48 UTC+1, Nick wrote: > > I've created a properly optimised and searchable PDF with the correct > metadata from the JPGs below which can be found in the group library under > *Nixie > Tube Data -> Application N

[neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

I've created a properly optimised and searchable PDF with the correct metadata from the JPGs below which can be found in the group library under *Nixie Tube Data -> Application Notes*. A direct link is https://drive.google.com/open?id=1xC765xBVZGuaampIQOWhEyG5oeEfr9Bw I would encourage folk

Re: [neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

Another document on multiplexing can be found here: http://www.tube-tester.com/sites/nixie/dat_arch/ZM1200_valvo.pdf it shows how the Pandicon, the ZM1200 series of Nixies, designs should be made to get them to work properly. It shows a string of zeners in the power supply section that delivers

Re: [neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

You can also read about multiplexing Nixies here: https://threeneurons.wordpress.com/nixie-power-supply/ starting with the text "*Nothing Turns-ON Instantaneously"* /Martin -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from thi

Re: [neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

W dniu piątek, 19 stycznia 2018 19:01:52 UTC+1 użytkownik Jon napisał: > > Tomasz - which nixies are you using in this application? I seem to > remember some discussion from years ago that some tubes (maybe ZM1000?) > were particularly prone to ghosting and leakage effects even at microamp > cur

Re: [neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

Leakage in the NPN is of no concern. That gives a voltage across the 2k2 resistor of next to nothing, and won’t cause anything to wake up the PNP... Op vr 19 jan. 2018 om 21:29 schreef gregebert > From the datasheet, collector leakage current is about 100nA. Assuming all > of the NPN leakage cur

Re: [neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

>From the datasheet, collector leakage current is about 100nA. Assuming all of the NPN leakage current is amplified in the PNP, you would get 4-5uA of actual leakage to the anode from the PNP. That doesn't seem like enough current to me to cause a visible glow in a nixie. Your scope probe (10me

Re: [neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

And use a 50/50 divider, to make the voltage between anode and cathode of the tube as low as possible. Do not set it at 120V, but go for 90V, using equal resistors. If your HV is higher than 180V, try reducing that to at least 180V or perhaps 170V. Op vr 19 jan. 2018 om 18:52 schreef Frank Bemelma

Re: [neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

Tomasz - which nixies are you using in this application? I seem to remember some discussion from years ago that some tubes (maybe ZM1000?) were particularly prone to ghosting and leakage effects even at microamp currents. Jon. -- You received this message because you are subscribed to the Goo

Re: [neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

Well, the voltage divider is at half of 180V, more or less 90V. Even is some current was leaking through your anode transistor, the voltage between tube anode and tube cathode, is still to low to cause any glow. The tube’s digit will only glow with a fully turned on anode transitor and cathode tran

Re: [neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

W dniu czwartek, 18 stycznia 2018 19:29:02 UTC+1 użytkownik Frank Bemelman napisał: > > It is not the transistor that keeps conducting or leaking. The voltage you > see at the anode comes from leakage from floating cathodes from the other > tubes. > Oh it was just seconds ago when I underst

[neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

W dniu czwartek, 18 stycznia 2018 13:54:32 UTC+1 użytkownik GastonP napisał: > > Another option (just to help troubleshooting but involves no soldering) is > to change the driving sequence to avoid adjacent tubes to be driven one > after the other. For example if you are driving the tubes in 1-

[neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

I can recommend reading the Burroughs document N101 on multiplexing Nixies which can be found here, if you haven't done so already: http://worldpowersystems.com/ARCHIVE/Burroughs/index.html . /Martin -- You received this message because you are subscribed to the Google Groups "neonixie-l" gro

Re: [neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

It is not the transistor that keeps conducting or leaking. The voltage you see at the anode comes from leakage from floating cathodes from the other tubes. What you can do to kill the ghosting is connecting 10 diodes to all tube cathodes. Connect the anodes of the 10 diodes to the 10 cathodes of th

[neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

I've checked the driving circuit before posting with oscilloscope and there is absolutely nothing incorrect visible up to MMBTA92s collectors. I've taken photos of the bases of PNP transistors - the signal is clean, as visible below:

[neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

Hi Tomasz, to me it looks like there is some kind of either capacitive coupling or leakage between the different drivers. You can see this from the different levels of the voltages at anode. Besides what has been suggested to you, I would strongly advise to add a bleeder resistor between the

[neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

Thanks, I'll try pulling to HV/2. I already tried pulling down to GND, but it didn't change much. It decreased the "discharge time" of incorrectly opened PNPs. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and st

[neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

I didn't look at your waveforms (or schematics), but if your switching speeds are very fast, this can cause transistors to turn on when they should not. The inter-element capacitance can pull the control element to the active state, even if it's not reflected on the pin itself. Terry On Wednes

[neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

I'll be able to check it in few days. Power supply won't be overloaded for sure, it's a 0-300V 1A lab power supply :) W dniu środa, 17 stycznia 2018 22:03:24 UTC+1 użytkownik gregebert napisał: > > Can you check the signals on all 4 of the NPN bases at the same time? > Neglecting blanking, they

[neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

Can you check the signals on all 4 of the NPN bases at the same time? Neglecting blanking, they should look like 4 pulses, each 25% duty-cycle, with no overlap. The 4th picture looks like this sequence: - Anode 1 on - Anode 1 & Anode 2 both on - Anodes 1,2, and 3 on - Anodes 1,2,3,

[neonixie-l] Re: MMBTA92 & MMBTA42 anode switching circuit problem

For some reason pasting photographs in google groups doesn't work as I would wish it to. So enjoy the two extra copies of photos at the top, which I didn't see, as I was trying to paste something at the point I was writing at that moment. -- You received this message because you are subscribed