Calling EE's: Electrical phenomenon explanation requested!

[Qbranch]

Hello all, while sitting at my desk here in my dorm room, I've just witnessed a fascinating phenomenon. There's a little backstory:

The flourescent light over my desk went out, so I took the bus to Wal-Mart and bought an immitation banker's desk lamp. Upon getting it all put together, I read that it was the type you touch any part of it that's metal to cycle through off, dim, medium, and bright.

Here's where the phenomenon comes in: Whenever I turn on my broken flourescent light (the starter filaments in the bulb come on but the light doesn't start), my banker's lamp changes brightness, just like if I had touched it. It even works at a range of a few feet (between the broken flourescent light and the desk lamp).

I'm sure it's some sort of electromagnetic phenomena... but what's really going on?

-q

[IKE]

http://howthingswork.virginia.edu/in...ght_bulbs.html

This link has both how touch lamps and flourescent lamps work. My guess is that your flourescent lamp is giving off a High Frequency charge that the touch lamp responds to as a capacitance change.

I think it was Tesla that lit flourescent lights without even connecting them to wires.

[Dick Linn]

Have you tried touching the bulb (the glass part) in the fluorescent lamp to see if that will start it? I have one over the kitchen sink that seems to like a bit of extra stray capacitance or whatever to start up in the morning.

[Protronie]

Awesome but strange....
Why take a bus... didn't you bring your ride to school with you?

-p

[RyanCahoon]

After reading the linked page about how touch lamps work, it seems to me that the starter coil in your old lamp that you mentioned is most likely what's causing the new lamp to change. Fluorescent starter circuits work by pulsing current on and off (PWM anyone?) through the fluorescent gas, which helps to ease the atoms into the charged state, which is what causes them to fluoresce. Fluorescent lamps also usually use a transformer to step the voltage up that they use to power the lamp. So here you have a high voltage, fluctuating electric field. High voltage means the field is large, and allows the electrons to move around a lot (same idea that enables things like lightning and Jacob's Ladders) this fluctuating field is probably disrupting the fluctuating field that exists in the touch lamp (like inductive power), causing enough of a disturbance that to the device, it appears as if something has touched it.

That would be my guess.

--Ryan

[Qbranch]

So... I'm calling the concesus on my luminary phenomena that my flourescent lamp starter induced a current in the lamp's body which spooked the capacatince change detection circuit.

Cool! *goes back to experimenting with how far the bank lamp can be from the flourescent*

-q

[DonRotolo]

Originally Posted by Qbranch

*goes back to experimenting with how far the bank lamp can be from the flourescent*

Also vary the relative orientation of the two lamps - parallel will have a greater effect (=distance) than perpendicular.

The induced current from the old lamp into the new is indeed being treated like a change in capacitance by the touch lamp controller.

Now try it with electrical shielding betwen the two (e.g., aluminum foil) and then magnetic shielding (steel or some other metal that conducts 'magnetism') - what's the effect then? What does this tell you as to whether the phenomenon is electrical or magnetic in nature?

Don

[Al Skierkiewicz]

I think thee is something more simple going on here. The touch sensor by design is a very high impedance and as such is sensitive to electrical noise. As the starter tries to pulse the ballast in the old lamp, a noise pulse is produced. The noise travels through the air and false triggers the touch sensor. I bet the same effect will be had during cold dry months with static discharge.