Please point me (Noob)  in the right direction. - Page 1
Forum section: electronics / projects

author: wblackledg
author_rank: Regular Contributor
timestamp: March 28, 2015, 01:35:20 am
content: Please point me in the right direction. I'll try and figure it out from there.Noob question,So how can I (my 6V battery powered circuit) detect the presence of an entity (entering a room, touching the device, talking, etc. ) and and turn on otherwise stay asleep and not drain the battery? Capacitance based on touch? noise detection? Motion detection?if you can link me to an example circuit that would be great too.thanks in advance.

author: xrunner
author_rank: Super Contributor
timestamp: March 28, 2015, 01:53:59 am
content: One way other than what you mentioned is to put a visible or IR laser on one side of the door and a detector on the other side (if there's only one way in.

author: wblackledg
author_rank: Regular Contributor
timestamp: March 28, 2015, 02:00:37 am
content: Quote from: xrunner on March 28, 2015, 01:53:59 amYes, thats another idea I hadn't thought of.Basically I'm looking to detect something very small critter (bug) going into a small hole. I probably should have mentioned that earlier.thanks.

author: xrunner
author_rank: Super Contributor
timestamp: March 28, 2015, 02:10:30 am
content: Quote from: wblackledg on March 28, 2015, 02:00:37 amWell, if it doesn't weightoo muchto little and it's walking on the ground you might be able to use a FSR (force sensitive resistor) but you'd have to look at the specs to make sure it would register a small weight.

author: wblackledg
author_rank: Regular Contributor
timestamp: March 28, 2015, 02:26:40 am
content: that's really cool! thanks. I'll have to read up on how it actually works because I'm not familiar with it.

author: xrunner
author_rank: Super Contributor
timestamp: March 28, 2015, 02:32:23 am
content: Quote from: wblackledg on March 28, 2015, 02:26:40 amI used to have one around here somewhere ... I'd test it for you. How much does the bug weigh is the real question.

author: wblackledg
author_rank: Regular Contributor
timestamp: March 28, 2015, 02:34:21 am
content: Quote from: xrunner on March 28, 2015, 02:32:23 amI guess like a honey bee or so. (oh and thanks for offer).I found this.I think this is pretty close to what I want.Anybody have a clue what the circuit would look like?http://www.nature.com/ncomms/2014/140804/ncomms5560/fig_tab/ncomms5560_F1.htmlwonder what the circuit would look like?

author: mrkev
author_rank: Regular Contributor
timestamp: March 28, 2015, 02:46:08 am
content: Basically you can use any "property" of environment that is gonna change in the presence of that bug.- it's large enough and you want it to go through narrow space - > use light gate (f.e. photo transistor with LED)- weights enough - > use wblackledg's method.- makes sound or vibrations in otherwise quiet place - > small electret microphone- it's warm -> IR detector- If it likes water -> monitor water levelThere is always gonna be some power consumption since you need the detection circuit to operate at all times. uC with sleep mode would be IMHO best solution. Just make the circuit switch on the "wake up" interruption.

author: mrkev
author_rank: Regular Contributor
timestamp: March 28, 2015, 02:54:39 am
content: In the case you've posted, I would make oscillator with tank's cap made from two electrodes (dielectric is air) and measure the frequency with uC. When freq. change in short time, that means something is between the electrodes.It could be done drawing few mA (depends on how you program the uC)...

author: wblackledg
author_rank: Regular Contributor
timestamp: March 28, 2015, 03:04:11 am
content: Quote from: mrkev on March 28, 2015, 02:54:39 amvery cool. Do you know of a schematic you could point me to that uses this on anything, and I believe with some playing around on my end I can figure out how to use it in my circuit (I hope).thanks.