> Thanks everyone for answers, I will probably use some cheap VFD to test the
> 9.2% PWM @3,3V on high frequency. I'll measure current and will look on it on
> oscilloscope to see on which frequency the filament will be heated so
> frequently, that it won't have time to really cool (current
Thanks everyone for answers, I will probably use some cheap VFD to test the
9.2% PWM @3,3V on high frequency. I'll measure current and will look on it
on oscilloscope to see on which frequency the filament will be heated so
frequently, that it won't have time to really cool (current will be
[mailto:neonixie-l@googlegroups.com] On
Behalf Of Bill van Dijk
Sent: Tuesday, March 07, 2017 2:40 PM
To: neonixie-l@googlegroups.com
Subject: RE: [neonixie-l] Rookie question about driving VFD filament
<20% of 5V is technically 1V >
Please let me add a word of caution on the pwm issue here.
rom: neonixie-l@googlegroups.com [mailto:neonixie-l@googlegroups.com] On
Behalf Of taylorjpt
Sent: Tuesday, March 07, 2017 12:30 PM
To: neonixie-l
Subject: Re: [neonixie-l] Rookie question about driving VFD filament
An important aspect of the filament has not been discussed in this thread:
Yes, the
While on the subject of VFD's, anyone know of a particular VFD that has a
long lifespan ?
I'm reluctant to build a clock with them unless I'm certain they have a
long lifetime, as I've seen the VFD on my kitchen stove is fading near the
filaments (I suspect electron bombardment on the cathodes
An important aspect of the filament has not been discussed in this thread:
Yes, the filament needs to be heated so that it emits electrons efficiently
but it also sets the potential difference between the cathode (Itself) and
the anodes (the segments). For the later reason you can't simply
No, the filaments are tungsten and tungsten has a huge positive
temperature coefficient. The ideal drive would be a constant current,
voltage capped source. A resistor approximates that quite well.
I would not connect them in series for the same reason it's a bad idea
to connect vacuum tube
> Do I understand correctly, that they work just like a resistor?
It *is* a resistor, one with a largish positive temperature coefficient.
> My plan is to drive IV-6 filament by directly PWMing it from 5V or 3,3V. It
> normally requires 50mA@1V, so if the filament works just like a resistor,
Hello Ten
> Another idea is to connect 4 tubes in series. Of course it will make a
> voltage gradient across tubes, but I plan to drive anodes at 50+V, so maybe
> it won't be visible - does anybody have any experience with driving
> filaments like that?
> A step-down converter sounds good, but I
