Neon Indicator bulbs/resistor

[selldoor]

Hi Chaps - need a bit of guidance - still fixing up the fridge freezer I started on almost 12 months ago!!! lucky we only get a couple of days for summer!!

Last pieces of the puzzle are the light - I can manage that - needs a new bulb and the green power indicator light.
It too has gone - weird,two bulbs gone, it isnt that old and eventually it really only needed a new thermostat ( Yes 12 months!!! but hey im busy)
Anyway I am also tight ( Do they use that in the US for someone who likes to hold on to their cash) so whilst I can just go and buy a nice new green light, I have taken the old one to pieces. Inside is a neon bulb and a resistor and I can buy 5 plain bulbs for less than the green one.
Probably a false economy as i'll never use the other 4 or will need one and wont be able to find them - anyway its still cheaper.

I am pretty sure that its Brown green yellow gold 150kohms but the yellow could be faded orange but I dont think so as that would be 15kohms which is nowhere near what I THINK it should be based on a complete guess looking at the ones I can buy.
Ha ha ha cant believe its taken so long to realise I can measure it, its not like its burnt!! - 150k it is.
Which nicely leads on to the actual query.
If I have a 150k resistor which if either of these bulbs will be best
http://cpc.farnell.com/jsp/search/pr...B2005%2B206059

I would prefer to use the 4mm bulb as it is nearer to the size I have but in the description is says Series Resistance @ 240V:220K 1/4W whereas the 6mm one says Series Resistance @ 240V:180K 1/4W.

I am guessing this means that for them to operate correctly that is the resistor they should have in series - anyone know? and anyone know what will happen if I use a 150kohm resistor with them

[crtfool]

Re: Neon Indicator bulbs/resistor

In theory, with a smaller than required resistor, you will get a higher voltage applied to the bulb - it could either be a bit brighter, or it could burn out much quicker. Why don't you just buy a replacement resistor to match what the bulb requires?

Or, since you are planning on buying 5 bulbs anyway, just try 1 and see what happens - the worst is that you would kill 1 bulb prematurely. Tape the remaining bulbs to a space inside the chassis if the refrigerator for future use - this way you will be able to find them when needed.

[selldoor]

Re: Neon Indicator bulbs/resistor

Hi thanks for that - Do you know for certain that the bit in the description
means the resistance of the resistor you are supposed to use with it.
I have also been looking on old board for a correct value or nearer resistor - if I have to buy one ( probably a pack of 10/20 ) I may as well just buy a green bulb. Yes when I get the bulbs I will just try one and see how long it lasts.

[crtfool]

Re: Neon Indicator bulbs/resistor

I know that all neon lamps have a resistor in series with the bulb - I'm pretty sure that they are not talking about the actual resistance of the lamp itself.

I just did some research, and it seems that the resistor is for current limiting purposes.

[selldoor]

Re: Neon Indicator bulbs/resistor

I have found a 33k resistor so with the 150 that will be a lot closer.
It will be a couple of days before I can get to it and will post the result.
Thanks for the help.

[budm]

Re: Neon Indicator bulbs/resistor

Is it NE-2?
http://www.allspectrum.com/store/neo...ads-p-146.html

[selldoor]

Re: Neon Indicator bulbs/resistor

Yes - Ithink its a NE2 4x10 I might get the bulbs later today.

[redwire]

Re: Neon Indicator bulbs/resistor

I think you've got lamps intended for 120Vac. NE-2 likes 90V around 0.3-0.6mA but the Chinese use 15,000 ohm resistors and drive them hard. So they die after a year or two. For 240Vac use 250k or so gives long life but a bit dim. 150k is 1mA and fine. There are also green neon lamps you can use.

[selldoor]

Re: Neon Indicator bulbs/resistor

Hi thanks for all the replies - got it fixed - its a bit dim ( like me eh HaHa) tried various resistors but still dim so probably the wrong amp bulb. Not to worry it glows enough to see the power is on and I suppose it saves a miniscule amount of electricity!