Many thanks for all your replies and advice.
DC seems t be the way then, with some series resistance on the filament
supply.
I'll start in that direction and get something working on the bench.
- Richard
On Friday, 16 June 2023 at 20:32:01 UTC+1 Moses wrote:
> Richard,
>
> Same here! I
Richard,
Same here! I started to experiment with the IV-21 tube and how to drive it
recently. I have some drivers on the way. I don't have much experience with
VFDs at the moment.. but I did light one up on the bench recently.
I used the datasheet recommended filament voltage/current on the
Adding series resistors also reduces the current spike during power-on.
Hard to say what fails first with VFD's; ones that I've seen such as the
displays on kitchen appliances which run 24/7 show phosphor degradation
after a few years. If you frequently power-cycle the filaments, then you
Assuming you drive the filaments in parallel rather than in series, a DC
voltage would be fine. If you drive them in series then (I assume) the
voltage gradient might be visible. A decision to drive in parallel has a
knock-on effect - I couldn't come up with an AC drive that had a constant
The IV-22 has very low filament voltage. Something like 1.2V IIRC. That
makes the voltage gradient across the display face low and I didn't notice
a brightness gradient while running one with DC. Used a simple buck
converter for the filament and a boost converter for the anodes and grid.
fredag
You'll be fine with DC. If you can't see a visible difference in brightness
across the tube then it probably doesn't matter. People say there are
lifespan issues with DC but I haven't seen that yet on my VFD clocks. I
just use DC and bias the grid ~ -3vdc.
On Thu, Jun 15, 2023, 10:45 PM Richard
