Post by thread:help infrared detector want read right when motor

I bet it is RF or EMI noise being picked up by the detector. Look at the data output from the detector when the motor runs and see if it doesn't suddenly become very active as if it was receiving IR data. I have used Sharp detector modules before and they absolutely require a high quality ground. Mine used to false-trigger if I brought a finger tip near the photo transistor in the front of the detector case. I was either emitting short bursts of 33 KHZ infrared carrier or inductively coupling noise in to the high-gain amplifier which is in that metal can along with the photo pickup, a band-pass filter, and some switching circuitry. Basically, those things are extremely unstable if not grounded well. Obviously, if they pick up a steady stream of noise pulses, your data capture system will never see valid frames to lock on to and it will just discard all incoming data. Martin McCormick WB5AGZ Stillwater, OK OSU Center for Computing and Information Services Data Communications Group Kent Berry writes: > the infrared detector want read right when i have the motor run( i,m using >the L293d motor control chip ) when the motors are not running the detector >works fine >i dont know if its the noice or the ground or both can some one help

Martin McCormick wrote: > I bet it is RF or EMI noise being picked up by the detector. > Look at the data output from the detector when the motor runs and see > if it doesn't suddenly become very active as if it was receiving IR > data. I have used Sharp detector modules before and they absolutely > require a high quality ground. Mine used to false-trigger if I > brought a finger tip near the photo transistor in the front of the > detector case. I was either emitting short bursts of 33 KHZ infrared > carrier or inductively coupling noise in to the high-gain amplifier > which is in that metal can along with the photo pickup, a band-pass > filter, and some switching circuitry. Basically, those things are > extremely unstable if not grounded well. Obviously, if they pick up a > steady stream of noise pulses, your data capture system will never see > valid frames to lock on to and it will just discard all incoming data. Ditto. My thoughts and experiences exactly. Michael ************************************************************************* When the way of the Tao is forgotten, kindness and ethics must be taught. Men must learn to pretend to be wise and good. -- Lao Tzu *************************************************************************

In message <spam_OUT35E0AB9D.27D6TakeThisOuTblacksand.com>, Mike Ghormley <.....mikegKILLspam@spam@BLACKSAND.COM> writes >Martin McCormick wrote: > >> I bet it is RF or EMI noise being picked up by the detector. >> Look at the data output from the detector when the motor runs and see >> if it doesn't suddenly become very active as if it was receiving IR >> data. I have used Sharp detector modules before and they absolutely >> require a high quality ground. Mine used to false-trigger if I >> brought a finger tip near the photo transistor in the front of the >> detector case. I was either emitting short bursts of 33 KHZ infrared >> carrier or inductively coupling noise in to the high-gain amplifier >> which is in that metal can along with the photo pickup, a band-pass >> filter, and some switching circuitry. Basically, those things are >> extremely unstable if not grounded well. Obviously, if they pick up a >> steady stream of noise pulses, your data capture system will never see >> valid frames to lock on to and it will just discard all incoming data. > >Ditto. My thoughts and experiences exactly. > One other point, is the supply to the detector well decoupled, it should be fed via a resistor and have a decoupling capacitor to ground - not doing this really messes them up. -- Nigel. /--------------------------------------------------------------\ | Nigel Goodwin | Internet : nigelgKILLspamlpilsley.demon.co.uk | | Lower Pilsley | Web Page : http://www.lpilsley.demon.co.uk | | Chesterfield | | | England | | \--------------------------------------------------------------/