Hi David,

I do indeed have a scope and am starting to get the kind of results i
wanted now I have changed out the PSU for a more capable one.

So far, from my testing:

HV 200V.
Anode resistor of 3k9.
Voltage across anode resistor during pulse is between 42 and 48v (depending
on the individual tube - some are a little different)
This equates to a pulse current of about 12.3mA, which is within spec for
an IN14, which specifies a maximum pulse current of 13mA.  (and no idea
about an IN12, as I can't find any reference to multiplex current mode in
any of its' data sheets, but as it's a similar size, I'm assuming similar
values will be OK.

With two 'test' tubes I didn't seem to have any issues with ghosting as
long as a sensible blanking interval is applied, but once I've put the
whole assembly together, I will see what happens this time!

Thanks for the advice!

David

On Fri, 1 Feb 2019 at 05:05, David Forbes <[email protected]> wrote:

> Hi, I have some experience building multiplexed Nixie clocks that work
> correctly. Firstly, do you have an oscilloscope? It's difficult to
> understand what is going on without one.
>
> I found that 190V was sufficient to run ZM1040 tubes with a 10k anode
> resistor shared by all tubes. I would have to measure it again to know the
> current and anode voltage, because it's been about fifteen years since I
> last made one.
>
> Ghosting is a problem unless you time the anode and cathode switching
> properly. I turned off the anode, waited a few milliseconds for the tube to
> turn off, changed the cathode selection, waited a few milliseconds, then
> turned on the next anode. I also used PC board cathode wiring instead of
> discrete wires, to reduce capacitance.
>
> I remember that the anode current was 5 mA, and the anode voltage was
> 140V, but I could be off.
>
>
>
> On Thu, Jan 31, 2019, 4:46 PM David Pye <[email protected] wrote:
>
>> Still testing,and indeed, finding gremlins :-/
>>
>> Even the copy of Elektronische Anzeigebauelemente Electronica 171 has a
>> gremlin in it, being largely misprinted with huge sections missing,
>> including conveniently, the section on pulsed nixie operation.
>>
>> On a slightly different note, when anode-multiplexing, I can't see why
>> one anode resistor doesn't suffice, as only one tube is ever on at once.
>>
>> I was pondering this kind of layout:
>>
>>
>> HV supply->Anode resistor->Multiplex drive circuitry->TUBES
>>
>> Any reason why that would be ill-advised?
>>
>> David
>>
>> On Fri, 25 Jan 2019 at 20:53, gregebert <[email protected]> wrote:
>>
>>> Make sure you test the DCDC converter under full-load. Every one of
>>> these I've ever designed & built always worked beautifully under low load,
>>> and as the load increases all sorts of gremlins start creeping out of the
>>> jungle.
>>>
>>> Some of them are easy to spot, like overheating. Others require you to
>>> go poking around with a scope to find excess voltage or current.
>>>
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