Please explain human EM interference with my XMAS lights

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Discussion Overview

The discussion revolves around the phenomenon of human electromagnetic interference with electric candles, specifically how the proximity of a human body can cause these devices to turn on or off. Participants explore the electrical properties of the human body and the behavior of different types of light bulbs, including incandescent and LED.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes an experience where an electric candle turned on when their hand was near, questioning the underlying mechanism and why this does not occur consistently.
  • Another participant suggests that a floating CMOS logic input could be responsible for the behavior, noting that static charge can influence high-impedance inputs.
  • A participant inquires about the presence of an on/off switch for the candle, seeking clarification on how the device operates normally.
  • It is confirmed that the candle does not have an on/off switch, prompting further questions about the type of bulb used and whether the behavior persists.
  • It is revealed that the bulb is incandescent, and the participant notes that there were multiple lights exhibiting this behavior while others did not.

Areas of Agreement / Disagreement

Participants express curiosity and propose various explanations for the phenomenon, but no consensus is reached regarding the exact cause of the behavior or why it occurs with some lights and not others.

Contextual Notes

The discussion includes assumptions about the electrical properties of the human body and the specific characteristics of the electric candle, but these aspects remain unresolved and are not fully explored.

stevenstritt
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I am aware that the human body has electrical properties, But was baffled by what I witnessed Christmas Eve. I had a malfunctioning electric candle in the window. I picked it up to check the tightness of the bulb, and it immediately came on. I set it down and it went off. Three times this happened before I discovered that I did not even need to touch it, but merely move my hand close and it would light up. My question is how can so simple a device as a light bulb react this way, and why does this not happen all the time?
 
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stevenstritt said:
I am aware that the human body has electrical properties, But was baffled by what I witnessed Christmas Eve. I had a malfunctioning electric candle in the window. I picked it up to check the tightness of the bulb, and it immediately came on. I set it down and it went off. Three times this happened before I discovered that I did not even need to touch it, but merely move my hand close and it would light up. My question is how can so simple a device as a light bulb react this way, and why does this not happen all the time?

Often with weird stuff like that, there is a floating CMOS logic input that is the cause. A floating CMOS logic gate input has very high input impedance, and static charge on your hand can generate enough of a field to push the gate input high and low. I've had this happen to me several times on prototype circuits where I wasn't paying attention and didn't tie off unused inputs.

How does this candle normally turn on and off? Does it have a button?
 
There is no on/off switch
thanks
 
stevenstritt said:
There is no on/off switch
thanks

Was the bulb incandescent or LED? Does it still exhibit this weird behavior?
 
It was incandescent. It was not actually at my house so I don't know. There were actually 3 lights behaving this way, and 3 others that didn't
 

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