I was searching for a project that my friend Pat (an expert woodworker) can do while the surgery on his right elbow heals.
We are both in our late 50s, early 60s and play a weekly game of EDH down at the local. I'm into hobby electronics and am basically a toymaker.
I decided to start a little project, something that would let me work in Pat's wood shop, doing the stuff he can't right now (due to the surgery), and help keep him from going crazy with enforced idleness.
I came up with a life counter that uses IN-12 nixie tubes for the display, and rotary switches to adjust them. We wanted to use as much off-the-shelf components as we could, to minimize the amount of work in the woodshop we would have to do.
Here is what we have so far.
We've also come up with gears, images and so forth that will give this project a Steampunk / Dieselpunk feel to it.
We're making only three of them. Seems a waste to make just one, and more than three would make this a bigger project than I want.
You can see from the abacus-style life counter (I make those too) the scale of these devices.
We've made the final major addition to this project, one I thought of last night after seeing the reflected glare of the overhead lighting on the glass faces of the nixie tubes.
The old displays in the past used hoods to shade them so the nixie tubes didn't have to be driven hard for brightness (and shorten the life of the nixie tube).
So we added a 'hood' of leather. It looks pretty good. All we have left now is some trim, additional decoration, installing the 'power on' indicator and hitting it all with a protective polyurethane coating.
And finally, a picture to give you the scale of this unit....
We had to design and install a strobing circuit. The original setup used way too much current in order to keep the nixie tubes 'always on'.
We figured flickering them on and off really fast would still look good but reduce current consumption by at least 60%. We were only getting about an hour and a half out of our 4.5 volt battery pack.
Our strobing circuit worked well. We made some changes to the values of the resistors, added a diode and got a cycling rate where the display is only on 30% of the time, at 70 cycles per second.
The battery pack was bumped up to 6 volts and the unit now runs for 6+ hours!
I have completed the other two strobe circuits and tomorrow I install all the electronics in the other two units. I will have to change the current limiting resistor for the 'power on' LED, though. It is too bright as it is, right now.
The installs went well, but I neglected to calculate the current drain for the Nixies. Wound up putting a 10k resistor in series with each tube. This dimmed them a tiny bit but you can still see them quite well and the batteries should last even longer.
Here is the strobing circuit, with the 10k ohm resistor added: