On 03/12/15 02:27, Arfa Daily wrote:
"Fred McKenzie" wrote in message
...
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
Ha ! I built one too when I was an apprentice. I seem to think that the
circuit was in Practically Witless magazine. There used to be an aerosol
deodorant at the time which had a blue spherical cap. I had about 12
neons in my version, and had them poked through holes in one of those
caps - a bit like a WW2 sea mine. Quite by chance, the neon that flashed
slowest was the one that poked vertically out of the top. It was all run
from a single 90 volt battery, housed in a box made from modeling
plasticard under the deodorant cap. The one thing that I do recall is
that it also had a switch to alter the way the neons flashed. I seem to
remember that one leg of all the neons were joined together and
connected to battery -ve. Likewise, one leg of all the caps were joined
together. When they were left 'floating', the flash of the individual
neons was very 'soft' and hypnotic and random. The switch took the
commoned capacitor legs to battery -ve. With the switch closed, the
flashes were much 'sharper' making the whole display much more
'frenetic' looking. The current drain was so small that a battery lasted
a year or more (which was just as well, as they were expensive. I think
I still have a bunch of neons somewhere. I might try knocking one up
again ... :-)
Arfa
When I was about 10, I had a Tandy Radio Shack kit of 5 neon bulbs in a
row, that had a plastic box.... oh, hang on - let google find an image ..
(later)
that, the Science Fair Goofy-Lite
http://my.core.com/~sparktron/130P1.JPG
The Radio Shack, Science Fair, P-Box kits
http://my.core.com/~sparktron/pbox.html
Interesting that it flickered differently in the dark, or with ones
finger acted up differently.
Ran from 6V. There was an option of making it sequential rather than random.
Schematic
http://my.core.com/~sparktron/130P6.JPG
I also built the Three Transistor Short Wave Regenerative Receiver kit
http://my.core.com/~sparktron/110P1.JPG
Happy Days. Had to be quick with the soldering iron or the box would melt
--
Adrian C