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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details.

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Old 14th Apr 2015, 7:06 pm   #21
russell_w_b
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Default Re: "beehive" neon lamp

My Beethoven shotfiring exploder has a resistorless BC neon bulb in it. The function of it is not just to provide an indication that the main capacitor has been charged via the voltage doubler, but to 'strike' and prevent further charging.

It's driven from a hand-magneto type 26A as found in telephones, and so the internal resistance of the transformer winding will limit the current which, in any case, can't exceed 100mA.

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Old 15th Apr 2015, 7:32 am   #22
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Default Re: "beehive" neon lamp

I have got some of those type of neons.
They do indeed have resistors fitted in the base and work fine on regular mains AC voltage.
I also have one of the fuse holder type that can be used to indicate polarity on a DC supply as one end or the other lights up depending on polarity.
I have absolutely no idea about the stubby one that is a little bit larger than an MES though.
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Old 15th Apr 2015, 9:53 am   #23
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Default Re: "beehive" neon lamp

If you can get hold of a copy of Newnes Wireless Constructor's Encyclopedia a similar lamp is used in making a mechanical (scanning disc) television. I don't have a copy to hand but I am certain it mentions something about a resistor in the bayonet base that can be removed to make it glow brighter. I too recall these being used as a nightlight.
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Old 15th Apr 2015, 10:34 am   #24
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Default Re: "beehive" neon lamp

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Originally Posted by Refugee View Post
I have got some of those type of neons.
They do indeed have resistors fitted in the base and work fine on regular mains AC voltage.
I think my Beethoven exploder neon is another 'special' as it has no resistor fitted (it is written on the cap that it must not be burned without a series resistance).

When you think, I suppose neons were used far more prolifically in that period from the 1930s - 1960s and there must've been lamps made for all sorts of industrial purposes.
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Old 19th Apr 2015, 1:29 pm   #25
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Default Re: "beehive" neon lamp

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Originally Posted by Alistair D View Post
Never seen one that doesn't need current limiting but I prefer to prove it rather than assume.
Theory dictates they all need current limiters when used from a low impedance power source so you could consider that as proof, but someone could have found a practical workaround that we don't immediately recognise as a current limiter. I think its safe to have not the assumption, but the hypothesis that a resistor will be needed. Both for research purposes (a lot less work to disprove something from samples than to prove it) and for practical purposes (you won't have the problem of cleaning up shattered glass).

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Originally Posted by kalee20 View Post
Well, it doesn't act like a short-circuit (zero volts whatever the current), but it does have a negative incremental characteristic (voltage drop decreases as current increases), thus for stability, an external limiting impedance must be connected in series which is greater than this negative slope resistance.
Thank you, I worded that rather carelessly.
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Old 21st Apr 2015, 9:14 pm   #26
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Default Re: "beehive" neon lamp

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Originally Posted by Refugee View Post
I have absolutely no idea about the stubby one that is a little bit larger than an MES though.
I have an identical one, I think, to your "stubby" one.
It has a magnifying lens end as part of the glass bulb. It is fitted with an internal series resistor, and was 'rescued' from an old German-made (?pre-war) water heater. I think it was original, so it is probably of German manufacture. Tony.
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Old 22nd Apr 2015, 12:24 pm   #27
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Default Re: "beehive" neon lamp

I have no idea where my stubby lamp came from but it is a magnifying type and it has 380V stamped on it with no makers name. Perhaps it came from something industrial.
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Old 26th Apr 2015, 6:55 pm   #28
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Default Re: "beehive" neon lamp

I had a rummage in the overflowing "miscellaneous bulbs and neons" box in the workshop today, and found the German one mentioned in post #26 above, still in its chunky little Bakelite holder. It has neither a maker's name or built-in lens, but I found a similar one with an integral lens made by Osram. Both have internal series resistances. Tony.
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