View Full Version : Obstacle Detection problem

05-30-2009, 07:10 PM
hi friends
i built a Obstacle Detectior following the instructions in this blog


first it worked fine for upto 6 cms but when i reassembled the circuit the next day it didn't work i did give exactly the same connections but it just doesn't work !!
is there any way to check whether my ir reciever works or not i checked with my multimeter but it does not show any reading !!
by the way i did not use TSOP for this .[/url]

05-31-2009, 08:36 AM
Point a cell phone camera/ digicam at the ir led to check whether its turned on.
The fault is more likely to be with the ir LED or with the circuitry than with the photodiode.

05-31-2009, 11:35 AM
yes i did check with my cell phone camera and the IR LED is working fine.
when i connected the input pin from the reciever to the IR LED itself then the green indicator led lights up . so the circuitry is correct right ??

can anyone tell me what 4k7 in this circuit is


AND suggest another method that uses a TSOP instead of a photo diode !!

i found this on net


but the source code is incomplete , i am a beginner and i dont know how to write complicated programs

05-31-2009, 01:00 PM
4K7 is a 4700ohm variable resistor.

Better to chuck this and go for a TSOP. Using photodiodes for sensing is unreliable.
You dont need a microcontroller or any coding to make a obstacle sensor using a TSOP. Just a 555 running at ~38kHz is enough.

I will post more details regarding that if you want.

05-31-2009, 06:17 PM
YES i want to know more details about it please tell wat you know .

06-04-2009, 07:46 PM
Hi all,
Please google about this topic you'll find tons of info>I learnt TSOP's from google only.

Regards Akshay,

04-28-2010, 04:55 PM

A detailed guide on making obstacle sensor can be found here

May be this would help out most robotics beginners !

Have Fun!


04-28-2010, 08:42 PM
Woo! great tutorial! Now thats what I am talking about!!! Thanks!


04-28-2010, 10:29 PM
all ur tutorial are very nice and helpful, avinash_g :)

offtopic: Prashant bro, i want to send u a pm but i am not able to, also now cant find u on facebook.

04-29-2010, 06:39 AM
thanks all for the kind words !