I am trying to use a FET with a BS2 to be used as a "people sensor". Is this possible? Would the schematic at this link (http://www.amasci.com/electrom/electro-f1.gif) work?
2007-09-28 08:44:50 · 5 answers · asked by Quackmaster7000 1 in Science & Mathematics ➔ Engineering
The FET will detect a charge, so if people are walking by on a rug they may generate a static charge which could be detected. The link to a simple FET charge detector claims to be able to detect a person combing their hair with a plastic comb several feet away.
If you are looking for occupancy detection then an IR motion detector is the way togo.
An other simple means of detection are using light beams and an "electric eye" or pressure sensitive pads which sense the weight of a person walking on them.
2007-09-28 12:48:01 · answer #1 · answered by MarkG 7 · 0⤊ 0⤋
The charge held by a human is used in some elevator buttons, as well as capacitive changes caused by the finger, but these are contact devices.
Although the FET can have an input impedence of 100 Meg Ohms, that is hardly a good remote input device.
You can use optical, heat, motion, sound, radar (optical and RF), smell, and other methods to detect human presence, but you have to decide what level of complexity you want to endure.
I would use IR beams for simplicity. You break the beam, you must be human, or at least big!
2007-09-28 13:16:27 · answer #2 · answered by Warren W- a Mormon engineer 6 · 0⤊ 0⤋
Unlikely. That is a primitive electrometer. It does not detect humans but electrical charges. Since I can not think of any useful way to actually charge a human and then securely detect that charge, you will more likely get random signals from such a circuit than anything else.
If you want to detect humans, a simple IR motion sensor is MUCH better. You can probably get them for around $20 and they usually work just fine.
2007-09-28 08:54:34 · answer #3 · answered by Anonymous · 1⤊ 0⤋
That schematic wouldn't work because if it could detect humans it would also detect other things. You would have to do something like the source link to my post did. They dedicated a large portion of circuitry to filtering out unwanted noise. They also give good explanation as to why the noise filtration is needed.
2007-09-28 10:48:30 · answer #4 · answered by erdaj 1 · 0⤊ 0⤋
If it is extremely sensitive, it could possibly detect human presence, by the electrical signals, sent by the brain!
2007-09-28 09:45:21 · answer #5 · answered by Dragon'sFire 6 · 0⤊ 0⤋