Re: Neon light for AC outlet tester.

it would have to be the L-E one.

NT

Hi Jeff,

On page 81 of the GE Glow Lamp Manual, there is an interesting test circuit. It shows the neon light in a box with another light source. I think it explains why my ~20 year old battery powered fluorescent book lamp doesn't work very well at night when I use two rechargeable AA batteries. The lower voltage isn't able to turn on the lamp when there is no ambient light. I have to shine a flashlight on the lamp to get it to come on. When the batteries get a bit drained, it can take almost a minute for the light to come on with the flashlight trick. Once it's on, it provides very nice, even lighting.

Thanks for your reply.

The exact value isn't important. There's some effect on the brightness, but not much.

Yeah, that makes sense. The test setup shows that the light source is

A variation on the same test is to add something radioactive inside the neon lamp. The idea is for the neon to ionize at a lower voltage, thus making a better voltage regulator, memory device, or whatever. Radioactivity is also used to help fluorescent tubes start: Half-Life Emits Kypton-85 10.8 years Beta Promethium-147 2.6 Beta Tritium H3 12.3 Beta Thorium-232 14 billion years Alpha

My guess(tm) is that your 20 year old fluorescent tube had some kind of starting help from some radioactive material, which is long gone by now.

The voltage will not make much difference.

Many of the common neon bulbs will take about 90 volts to light. When they do light they act almost like a voltage regulator and will have about 70 volts across them no matter what the current is (within limits of blowing up) The higher brightness bulbs will often have more voltage across them. The resistor is to limit the current though them to a safe level. On an AC circuit you will have over 150 volts peak so most any common bulb will fire off.

If you have a way of slowly raising the voltage on the bulbs, you can check at what voltage they first light at. Then cut the voltage off and drop it to about 10 volts below that voltage. Then just touch the bulb and it will fire off. The extra heat eill be enough to make it light up.

Hi Ralph,

Thanks for the great explanation.