Possibly Steampunk++ ?

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3 years 2 weeks ago #7713 by mcc
Possibly Steampunk++ ? was created by mcc
Hi,

before I decided to build a Nixie clock myself I saw quite a few Nixie Clock-vidieos.

Some videos show Nixie tubes with "flickering" digits...the shutter speed of the camera interfered
with a multiplexing frequency of the digits I guess.

Somehow this gave the clocks an extra touch of retro-high tech look.

With "dont harm or stress the nixies" as the number one priority:
Would it be possible to modulate the current/voltage of the common anode of each
nixie to resemble this slow flickering (its more an up/down fading of the lumnosiity)
of the digits even for the human eye without shutter implants? :)

Only my two cent of an idea...

Cheers
mcc

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3 years 2 weeks ago #7715 by Ty_Eeberfest
Replied by Ty_Eeberfest on topic Possibly Steampunk++ ?
Interesting. I've never thought about this before. At first glance I don't see anything wrong with your idea, in the sense that it shouldn't do anything bad to the Nixies.Now, how to implement it??

My designs are all direct drive so that's what I thought about first. The most obvious way to do it in a direct driven cathodes situation would be to get 6 HV pnp transistors, one for each tube's anode. Dedicate 6 MCU outputs to the job of driving the bases of the transistors. Write code to do some sort of random or patterned PWM to vary individual anode currents. Could get a bit tricky but not impossible to avoid unwanted interactions between anode PWM and the cathode PWM I use to control overall brightness.

In a multiplexed design it might actually be easier. I'm thinking the multiplexing frequency and sequence could be left pretty much as-is, but add code to "skip" tubes in some random or patterned manner. By "skip" I don't mean literally skipping tubes in the multiplex sequence. I mean do something like keep the sequence always the same but "forget" to fire the output for the anode of certain tubes at certain times. That seems unclear but I can't think of a better way to say it so I how it makes sense.

Look into it later when the dust is clearing off the crater.

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3 years 2 weeks ago #7718 by mcc
Replied by mcc on topic Possibly Steampunk++ ?
Hi Ty, (thats a rhyme! :)

(I have a Rev4 kit)

I didn't look at the source code but from what Ian wrote there is a main loop, which does the multiplexing.
I would guess that each circle "feeds" another tube and the "ON" time is derived from the current calibrating
step, the LDR reading and from the count of tubes (six in this case). So the resulting "ON" time is the max.
value, which is vaild for a certain tube.
Shorten this time should not harm the tube, I think... (Ian?).
Ian said in the other thread I started, that the loop runs at 100Hz.
Would it be possible to "overlay" (based on calculation, not on other coded loop) another evaluation, which
counts from 0 to max.time in a much slower way and to subtract that value from the time, which is used to
switch on a single tube? That way, the tube would "flicker" and all tubes would flicker synchronously -- more
beliveable than a different luminousilty for each tube...
For that the uC had to be fast enough so that the loop cycle frequency (100Hz) is (mostly) only dependant from
the "ON" time of the tube - or in other words: The loop could run much faster theoretically, if the "ON" time of
each tube would be set to "0".
If this works, no extra hardware or hardware changes would be needed...

What do you think?

Cheers
mcc

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3 years 2 weeks ago #7719 by Ty_Eeberfest
Replied by Ty_Eeberfest on topic Possibly Steampunk++ ?

mcc wrote: That way, the tube would "flicker" and all tubes would flicker synchronously -- more
beliveable than a different luminousilty for each tube...


Okay, I misunderstood your first post and thought you wanted to see the tubes all flickering independently rather than synchronously. Synchronous seems like it should be much simpler and easier. I think you have the right idea with your thoughts on how to implement it in code, but that's really something Ian should address. I'm not anywhere close to an expert on Ian's code, haven't studied it much, my role here is really more to handle the other sections of this forum but if I see a fairly general question in this Arduino Kit section I jump in.

Look into it later when the dust is clearing off the crater.

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3 years 2 weeks ago #7724 by Ian
Replied by Ian on topic Possibly Steampunk++ ?
I don't think that there is a big problem doing this. The controller is really quite fast and the way it is implemented already should make this an easy task.

General
The inner loop does 1000 iterations, the outer loop does 6 (one for each digit). Inside each inner loop there is a start point (the digit turns on) and a stop point (the digit turns off). All of this happens at about 100Hz! There is a maximum on time (999) and a dimmed on time (read from the LDR and goes from 100 to 999, so even at full dimming the tube is 10% on).


Single digit flicker
This might be another option, but I don't think it is what you are asking for. From my experience, a flicker is easy to do, the eye is very sensitive to this and probably just missing an impression would be enough. I would do this by modulating the digit, skipping an impression according to a random value, so say 1 in 3000 chance of not being lit for the impression of a single digit, so that would mean each tube would flicker once every 5 seconds or so.

Modulate all digits
Just vary the value that you get back from the LDR reading slowly!

You won't harm the tubes. If you have IN-12B, they are bullet proof.

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