Audiojumble 03/03/24

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jack
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#31 Re: Audiojumble 03/03/24

Post by jack »

Morgan Jones wrote: Thu Mar 07, 2024 7:43 pm Arrived. Disappointment. Insufficient poke. Just about managed to produce an orange glow in an 85A1 neon). I am told that:

If it's blue, it's air.
If it's green, it's barium.
If it's pink-purple it's argon.

And Jack's large nixie managed a blue glow with his tester, which I assume is pokier.
Return it for a full refund!!

Either that or rebuild it as a BEAST!
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#32 Re: Audiojumble 03/03/24

Post by Morgan Jones »

I'll measure what it produces first. But it certainly didn't glow a fluorescent tube when held in contact.
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#33 Re: Audiojumble 03/03/24

Post by jack »

Morgan Jones wrote: Thu Mar 07, 2024 10:55 pm I'll measure what it produces first. But it certainly didn't glow a fluorescent tube when held in contact.
My one uses 8xAA, so 12V rather than the 6V of yours... Same available current, twice the voltage, so as you say, presumably pokier.
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#34 Re: Audiojumble 03/03/24

Post by Morgan Jones »

Further experimentation shows that you need to have your fingers on the contacts or surface of a fluorescent tube or regulator valve to make it work. But I don't recall you doing that? And it's certainly not in the instructions. I don't much like having my fingers near the tip of a high voltage. Perhaps a wire wool pad on the contacts to a lead to a battery contact at the tester would solve that problem. I wondered if yours might have bigger battery.

I've just measured 6kVpk-pk at 56kHz into 10M//3pF (high voltage oscilloscope probe). That's quite a bit. Not entirely sure such a thing should be readily available.
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#35 Re: Audiojumble 03/03/24

Post by Morgan Jones »

And I've just measured the current drawn from those AA cells. 1.92A! No wonder it pulses 1s on, 1s off - the battery needs time to recover. All in all, a dangerous piece of kit. No need to make anything pokier - if this can't produce a visible glow from residual gas in a valve, then it's probable that there just aren't enough gas atoms for their glow to be visible. I shall try again in the dark. But very carefully now I know how dangerous it is.

Explanation of attached 'scope trace. Ignore the aliasing, the time base was set slow to capture the current waveform as the oscillator started. The cursors give the current, so top cursor is at zero and bottom cursor midway between the (sinusoidal) peaks at -1.92A. Measurement was made using current probe in series with battery to tester. Battery is four AA.
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#36 Re: Audiojumble 03/03/24

Post by jack »

Maybe it’s the much lower frequency that forces the requirement for an earth path?

My unit runs around 270kHz…
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#37 Re: Audiojumble 03/03/24

Post by Morgan Jones »

Could very well be. Either way, it doesn't do what I hoped it might, and further thought and testing says extra poke wouldn't help. So I haven't spent 250 Euro or wasted time making something of my own. I suppose you could call that a win. And I've learned something. I've also noticeably flattened the AA cells (now reading 1.521V as opposed to 1.570V new).
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