...when one of the original prototypes was shipped to the UK, the customs folks here destroyed one of the tubes and the watch glass...
Not even a "Sorry" from them...
He looked at lithium cells, but the supplier would not let him have samples, and the MOQ was in the order of 10,000 units (or $$, I can't remember), so the "common camera battery" route was taken... Again, it's a compromise.
The reason the tilt-detector (a solid-state Analogue Devices unit) is used is that the HT converter is only activated whn the watch is at 45 degrees or so the the Earth. As you tilt the watch, you can just hear the HT boost converter starting (a very slight whstling) if you put your ear to the watch...
Assuming the HT supply is 90% efficient (typical for this sort of unit), to get 180VDC at 3mA, you need about 200mA at 3V from the battery - Obviously you can't let that run continuously as any battery would be flat in a few hours, hence the tilt-detectors.
Everything is a compromise... but it really does work...
Nicko
Making a nixie watch is enormously complicated - the power issues are complex - the tubes need 180VDC at a few mA to strike, but the batteries must last for 6 months or so. Each watch is hand made and uses lots of SMD components - the tubes are indeed not the smallest available as they are not made any more, so you can only use "common tubes" - the earlier 4-tube watch mentioned used JAN7009/4998 tubes which are extremely rare (the builder found a one-off small batch at a hamfest), and can't be used for commercial construction. It's not ideal, using these tubes, but it does work. Other common small tubes, like the Russian IN-17s have other problems (they are too deep).
I actually have one of these watches (a prototype), and it attracts nothing but admiration, even from my wife & daughter. You do need big wrists, though (I'm 6' 4" tall and 103kg)...
David only did this as a bit of fun - he deserves credit for producing something that's fun, with little profit (if any) for an awful lot of hard work.
Nicko
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...when one of the original prototypes was shipped to the UK, the customs folks here destroyed one of the tubes and the watch glass... Not even a "Sorry" from them...
He looked at lithium cells, but the supplier would not let him have samples, and the MOQ was in the order of 10,000 units (or $$, I can't remember), so the "common camera battery" route was taken... Again, it's a compromise. The reason the tilt-detector (a solid-state Analogue Devices unit) is used is that the HT converter is only activated whn the watch is at 45 degrees or so the the Earth. As you tilt the watch, you can just hear the HT boost converter starting (a very slight whstling) if you put your ear to the watch... Assuming the HT supply is 90% efficient (typical for this sort of unit), to get 180VDC at 3mA, you need about 200mA at 3V from the battery - Obviously you can't let that run continuously as any battery would be flat in a few hours, hence the tilt-detectors. Everything is a compromise... but it really does work... Nicko
Making a nixie watch is enormously complicated - the power issues are complex - the tubes need 180VDC at a few mA to strike, but the batteries must last for 6 months or so. Each watch is hand made and uses lots of SMD components - the tubes are indeed not the smallest available as they are not made any more, so you can only use "common tubes" - the earlier 4-tube watch mentioned used JAN7009/4998 tubes which are extremely rare (the builder found a one-off small batch at a hamfest), and can't be used for commercial construction. It's not ideal, using these tubes, but it does work. Other common small tubes, like the Russian IN-17s have other problems (they are too deep). I actually have one of these watches (a prototype), and it attracts nothing but admiration, even from my wife & daughter. You do need big wrists, though (I'm 6' 4" tall and 103kg)... David only did this as a bit of fun - he deserves credit for producing something that's fun, with little profit (if any) for an awful lot of hard work. Nicko