Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Old November 20th 15, 08:55 PM posted to sci.electronics.repair
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Default NE-51 Neon Bulbs

Just acquired a bunch of these lamps. They're in the same mini-bayonet
style as lamps like the #44/47. But would anyone know if these lamps can
be connected directly to 120 volts? Or do they need a resistor, @ if so,
what value?

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Old November 20th 15, 09:02 PM posted to sci.electronics.repair
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Default NE-51 Neon Bulbs

Madness wrote:

Just acquired a bunch of these lamps. They're in the same mini-bayonet
style as lamps like the #44/47. But would anyone know if these lamps can
be connected directly to 120 volts? Or do they need a resistor, @ if so,
what value?

Oh, you definitely need a series resistor. About 100K is typical.

Jon
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Old November 20th 15, 10:08 PM posted to sci.electronics.repair
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Default NE-51 Neon Bulbs



"Jon Elson" wrote in message
...
Madness wrote:

Just acquired a bunch of these lamps. They're in the same mini-bayonet
style as lamps like the #44/47. But would anyone know if these lamps can
be connected directly to 120 volts? Or do they need a resistor, @ if so,
what value?

Oh, you definitely need a series resistor. About 100K is typical.


Of 3 hits from searching NE51 - voltage rating was stated variously from
105 - 120.

Confusingly, one page displayed a picture of a filament bulb.

If a "bunch" of them is sufficient to sacrifice one, I'd peel the base cap
and see if there's a resistor in there.

Anything with a plastic lens cap probably has a resistor in the base.

Ionisation voltage is usually 70 - 90V, across the mains with a 100k
resistor in series would reveal the volt drop of the bulb - anything much
above 90V suggests an internal resistor.

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Old November 21st 15, 04:14 AM posted to sci.electronics.repair
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Default NE-51 Neon Bulbs

On Friday, November 20, 2015 at 2:55:22 PM UTC-6, Madness wrote:
Just acquired a bunch of these lamps. They're in the same mini-bayonet
style as lamps like the #44/47. But would anyone know if these lamps can
be connected directly to 120 volts? Or do they need a resistor, @ if so,
what value?


anywhere from 100,000 - 200,000 ohms, 1/2 watt or larger. Smaller resistor, brighter light, shorter bulb life.
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Old November 21st 15, 04:34 AM posted to sci.electronics.repair
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Default NE-51 Neon Bulbs

Thanks for the replies, everyone. I forgot to mention that my lot (about
30) is of vintage GE NE-51's, not the modern "NE-2 w/ plastic lens" variety.
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Old November 21st 15, 01:38 PM posted to sci.electronics.repair
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Default NE-51 Neon Bulbs

On 11/20/2015 3:55 PM, Madness wrote:
Just acquired a bunch of these lamps. They're in the same mini-bayonet
style as lamps like the #44/47. But would anyone know if these lamps can
be connected directly to 120 volts? Or do they need a resistor, @ if so,
what value?



Hello,

While I recall that they need the dropping resistor, since you have a
bunch of them, I might try destructive testing, and break one apart to
see if there is an internal resistor or not.

Regards,
Tim

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Old November 21st 15, 03:12 PM posted to sci.electronics.repair
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Default NE-51 Neon Bulbs

In article ,
Madness wrote:

Just acquired a bunch of these lamps. They're in the same mini-bayonet
style as lamps like the #44/47. But would anyone know if these lamps can
be connected directly to 120 volts? Or do they need a resistor, @ if so,
what value?


Madness-

NE-51 does NOT have a resistor inside!

One thing you can do with them, is build a relaxation oscillator. From
a 90 to 100 volt DC source, connect a series resistor, with a capacitor
across the bulb. Perhaps 470K Ohms and 1 uF. Try different values to
change the flashing rate. For smaller values, it can be used as an
audio oscillator.

Another variation is to have several bulbs, each with its series
resistor. But the capacitors are connected from bulb to bulb in a ring.
The result is a somewhat random flashing. I once built one with 5
generic neon lamps using two small 45 Volt batteries in series. Some
people would become engrossed, trying to figure out the flashing
sequence!

Fred
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Old November 21st 15, 03:32 PM posted to sci.electronics.repair
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Default NE-51 Neon Bulbs

On Sat, 21 Nov 2015 10:12:31 -0500, Fred McKenzie wrote:

For smaller values, it can be used as an audio oscillator.


I remember repairing a church organ that used such oscillators,
one for each key... That was some 40 years ago :-)
Sawtooth oscillators do produce a nice sound.

Cheers!


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