My guess would be that not having Perl is not the issue... unless you uncommented the section of code I mentioned in my last post. If you upload your code somewhere and post a detailed description of the error, perhaps I can help.Russell 27 wrote:I tried to compile something last night and did not work as expected, either I did not have it defined right in the code, or possibly the missing perl script was part of the problem, lots of things to know. Thought I would try adding the perl script as you had suggested in your post, see how that works.
I think I misunderstood: I thought you were offering to incorporate an alternate time display into xmas-icetube. But I guess you were explaining your current project?Russell 27 wrote:Not sure what you meant by that.jarchie wrote:Sounds nice. I'm open to code contributions.
I did stumble across that a while back, but before doing the IV-18 to-spec hack, I translated enough Russian to understand the voltages under which the tube was meant to be driven.Russell 27 wrote:I don't know if you have ever seen: IV-18_Dieter's tube archive, tube specs. [...] PhilD's attachment about VFD drives gives a very good account of tube magic, I'm sure you had already looked this over.
You have a good eye with respect to the Noritake guide; it's one of my favorite VFD references!
And thank you for pointing out those references, as I would not want to miss something.
The filament is meant to be run at 5v. The 75-95 mA figure is a property of the filament under normal operating conditions: 5v across the filament and a grid/anode voltage of 50v.Russell 27 wrote:It shows filament voltage @ 5V and current @ 75-95 milli amps, 85 Ma nominal.
I believe this is an error in that reference. The anode-grid voltage should be 50 volts with 70 as the absolute maximum. The to-spec hack uses 50-60 volts on the anode/grid and 4.6 volts of high-frequency square wave AC on the filament.Russell 27 wrote:Also shows Anode grid Voltage @ 20-30 volts and expected current. In your test you went to 50 volts, maybe just in trial.
That sounds fine. The acceptable range for the filament voltage is 4.3 to 5.5 volts.Russell 27 wrote:Board voltage is a nominal 4.72 volts and current I measured through filament from stock kit circuit is 65 milli amps. Little low according to specs.
My guess is that it has to do with the history of the design.Russell 27 wrote:22 ohms resistance comes from the inline 22 ohm resistor, not sure how ADAFRUIT came up with this value.
The Ice Tube Clock is loosely based on the inGrid Clock. The IV-18 illuminates more evenly when the filament is driven at lower voltage, so the inGrid design used that resistor to drop the 5v power to a lower voltage for the filament, deliberating running the tube out-of-spec.
Originally Q3 was a 2907 transistor with very little voltage drop, and R3 served its intended purpose. But without a resistor at the base, Q3 sourced too much current from the MCU, which caused some clocks to fail (see this thread). To fix the issue without redesigning the board, Q3 was replaced by a FET.
But as you've pointed out, the FET dropped voltage significantly and, when combined with R3, caused the dim digit issue, you mention. The filament does not fully heat near the ends, usually resulting in a final dim digit. Low filament voltage is also known to accelerate cathode poisoning, which may account for why the 3rd and 6th digit fade unusually quickly. Thanks to your excellent debugging, we know that the FET also causes problems with timekeeping during sleep.