we're working on a project which is about visualizing the approximate amount of people in a room. we dont want to count the people exactly, its more about the 'movement' or approximate fluctuation of people in that room. we want to visualize that with ten 12v fans one after another, upon which we'll put a textile fabric which then, when looked at it from the side, will show a curve, depending on which fan is blowing at which rate. each fan stands for one minute, so the whole installaton should visualize the last ten minutes activity in the room.
here is a sketch of our current setup. for simplicity weve only put one fan into the sketch, imagine there are ten of it, connected logically.. also, were using four uln2803, connecting three fans to each of it and the last one on the fourth..
- arduino gets power from macbook
- fans get power from 12v external power supply
- sketch shows only one fan, weve connected 10 in the same logical manner
- sketch shows only one uln2803, were using four, three fans per each, one on the fourth
- fan specs: 12v dc, 1.4 W
it looks like its random: when connecting more than one fan, at one time or another, without action from us, the notebook crashes... we assume the setup is sucking too much current from the computer... not a good sign... what could the problem be?
what kind of ir-sensor could we use as a simple light barrier? its really not about accuracy. we thought about using a simple distance sensor, place it in between the entrance door and let it trigger as soon as the distance measured is less than maybe one meter (when someone passes through)... could this work?
thanks for your help! s&r