| From: Alistair Fletcher | 6/02/99
15:55:56 |
| Subject: Touch Lamps | post id:
515 |
| I have a touch lamp. My question
is: Why do they only switch on through direct contact with the skin, and
not by touching the lamp with other
objects? | |
| From: Jeremy | 8/02/99
15:46:52 |
| Subject: re: Touch Lamps | post id:
610 |
| I think these "Touch lamps" you
are refering to are either: 1) a touch switch - in which case they rely on the capacitive reactance to ground via the human body in order to trigger a switch. or 2) a plasma lamp - which only requires a very small current to earth in order to affect the path of the high-impedance plasma source. In both cases it is the very slight reactive+conductive path to earth through the body which does it. If you don't make suitable contact then they just don't know your there! (Damn back to aliens again!) | |
| From: Michael Wain | 11/02/99
22:18:00 |
| Subject: re: Touch Lamps | post id:
1014 |
| Touch Lamps work on the fact that
the small amount of STACTIC ELETRICITY in you body is picked up by the
Touch plate that then tells the opto/triac in the lamp to sw ON or OFF ,
now in a eletic strom the small amount of STACTIC ELETRICITY in the air is
amplified by each stike as RF and that RF is picked up by the Touch lamp
which will send the lamp crazy, just listen to a AM radio on a distinct
station next time there's a strom arould
!..cheer's | |
| From: NIGEL | 20/07/99
22:34:21 |
| Subject: touch lamps | post id:
25197 |
| Why when you tuoch a touch lamp,
it can "tell" the difference between your bare flesh and turn on, and
anything else and not turn on? | |
| From: Grant | 20/07/99
22:37:01 |
| Subject: re: touch lamps | post id:
25198 |
From memory, by capacitance. Your body has a different value to that of other objects & the lamp has been 'tuned' to that value. | |
| From: Mark Dawson | 21/07/99
10:33:55 |
| Subject: re: touch lamps | post id:
25230 |
| Have you noticed that your touch
lamp viabrates? If I touch my lamp very lightly, I can feel a high freq.
vibration that goes when the power is disconnected. I believe these lamps work via a voltage drop. A small current is run through the metal base and when you touch it, the current drops and triggers the lamp. My lamp also goes on when I run my electric whipper snipper from the garage powerpoint (both are on the same circuit). | |
| From: otron | 21/07/99
11:11:09 |
| Subject: re: touch lamps | post id:
25247 |
There are numerous designs. One that I understand is by making your body act as an antenna when you touch the metal of the lamp. In detail, you may remember making a crystal radio as a child. How that worked was basically having a tuned circuit (an inductor and capacitor) connected to a diode. The diode was connected to as long a bit of wire as you could find. This wire picked up the radio waves (AM radio stations) and chopped off most of the carrier wave (ie the 612 to 1116KHz wave or carrier part of the signal), and left you with a modulated audio wave. I won't go into further detail than that - but this fundamentally is how those lamps can work. Your body increases the amount of radio waves (or noise in this case) that the diode picks up. Once a threshold of noise is reached, a DC voltage is produced (the level of RF noise in this case is directly proportional to the DC voltage produced). Now, if this DC voltage is deemed high enough, a signal is sent to additional circuitry to say "hey, someone must have just touched me, because I'm picking up a lot of noise". The lamp circuitry then toggles the light on or off or increments/decrements the lamp brilliance. Brilliant hey? | |