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Archived discussions on CrazyEngineers

@pratik20990 • 01 Oct, 2009
i have made an IR sensor circuit on breadboard which is this-

[​IMG]

i made this circuit on breadboard and when powered it with 9V battery the red LED started glowing. then i placed a piece of white cardboard with a 2cm thick black line over the IR LED and detector but the red LED doesnt stops glowing neither on black surface nor on white surface.😒😕

this is the spacing of my IR LED and IR detector as on breadboard-

[​IMG]

i could not understand what the problem is.😒😒😒 please help.😕😕😕
@pratik20990 • 01 Oct, 2009 one more thing my battery is getting heated up. is this normal?
@reachrkata • 02 Oct, 2009 Which is the IR receiver you are using? Can you give the part number?
From what i understand from the circuit, you want to stop the RED led when the IR Led is ON. Right?

- Karthik Raman
@pratik20990 • 02 Oct, 2009
reachrkata
Which is the IR receiver you are using? Can you give the part number?
From what i understand from the circuit, you want to stop the RED led when the IR Led is ON. Right?

- Karthik Raman

yes you are correct. i am making this circuit for line follower bot and according to this circuit when the IR rays fall on the receiver after reflection from a white surface the inverting input of the op-amp becomes high and the output becomes low which should stop the red led from glowing. i am using a piece of thin cardboard with a white surface for testing and what i think is the cause of the error is the improper reflection from the surface. should i use some other thing if yes then what? and i dont know the part number of my IR receiver but it is like this-
[​IMG]

one more thing is that i am not sure of the connections of my 10K preset resistor which is like this-
[​IMG]


i have connected the top pin to the + input of the op-amp and the other two pins are one to 5V and other grounded. moreover i have not adjusted its value i have just connected it to the breadboard as it is.
@Muffy • 03 Oct, 2009 @pratik20990 : Reverse bias the receiver diode, inter change the polarity . It should work. When ir is indecent on the diode the reverse leakage current increases ,saturating comparator, turning on led.
@shivang27 • 04 Oct, 2009
pratik20990
i have made an IR sensor circuit on breadboard which is this-

[​IMG]

i made this circuit on breadboard and when powered it with 9V battery the red LED started glowing. then i placed a piece of white cardboard with a 2cm thick black line over the IR LED and detector but the red LED doesnt stops glowing neither on black surface nor on white surface.😒😕

this is the spacing of my IR LED and IR detector as on breadboard-

[​IMG]

i could not understand what the problem is.😒😒😒 please help.😕😕😕
try to perform this,in separate palace where light is limited.it may be due interference of light.
@pratik20990 • 04 Oct, 2009
Muffy
@pratik20990 : Reverse bias the receiver diode, inter change the polarity . It should work. When ir is indecent on the diode the reverse leakage current increases ,saturating comparator, turning on led.
what do you mean by reversing the polarity? earlier i was connecting the longer leg of the diode to the supply voltage 5V and shorter leg was grounded. now i connected the shorter leg to 5V supply and longer leg was grounded. but still nothing happened.
@Muffy • 04 Oct, 2009 Reverse polarity of receiver diode . The diode labeled "IR receiver D1" , connect the anode of diode to pin 6 of lm324 and the cathode to the voltage divider network (at the junction of 2 resistors).

Make sure your transmitter led is working.Since IR is invisible to the human eye you cant look at it and figure out if its working or not. If your cell phone is equipped with a camera , train it towards the led and you should see a pale blue spot on the screen.
@pratik20990 • 08 Oct, 2009
Muffy
Reverse polarity of receiver diode . The diode labeled "IR receiver D1" , connect the anode of diode to pin 6 of lm324 and the cathode to the voltage divider network (at the junction of 2 resistors).

Make sure your transmitter led is working.Since IR is invisible to the human eye you cant look at it and figure out if its working or not. If your cell phone is equipped with a camera , train it towards the led and you should see a pale blue spot on the screen.

i tried this also and my led is also working fine but still it doesnt works out. tell me about the 10K preset resistor. do we have to alter its value for proper working.

pls if anyone can provide me any working circuit for this.😕😒
@just2rock • 08 Oct, 2009
pratik20990
i tried this also and my led is also working fine but still it doesnt works out. tell me about the 10K preset resistor. do we have to alter its value for proper working.

pls if anyone can provide me any working circuit for this.😕😒
yes check POT with preset value check & calculate 5k or so.reverse ploarity for IR D1 at OPAMP PIN6,same for against 100 ohm resistance...pls check resistance values sametime
@Jhonabraham • 12 Oct, 2009 Thanx for the advice. actually dont know which is the exact folder for this topic.

so the problem is:
i want to implement a feed back system which will read rotation of the the DC motor. now i m going to use IR-sensor. i need to know that what shall i do to make my IR-sensor working. i want to mount the transmitter and receiver across the GEAR or DISC mounted on the DC motor with a hole in it.
I want that when the Ir light passes through the hole of this gear/disc then the ir receiver shall generated a pulse.
distance between the transmitter & receiver is the main concern.(i want to make it that much sensitive).
@qaisarpk1 • 18 Oct, 2009 use LDR instead of IR . it is much easy to use and it will fine as line follower.
just put LDR in place of ur R1 resistor .
@pratik20990 • 19 Oct, 2009
just2rock
yes check POT with preset value check & calculate 5k or so.reverse ploarity for IR D1 at OPAMP PIN6,same for against 100 ohm resistance...pls check resistance values sametime

ya i had set the value of preset resistor to around 5K but still its not working.

please tell me about the reflecting surface which should be used as i am using a piece of white cardboard....
@Tula Dwarakanath • 14 Mar, 2012
pratik20990
yes you are correct. i am making this circuit for line follower bot and according to this circuit when the IR rays fall on the receiver after reflection from a white surface the inverting input of the op-amp becomes high and the output becomes low which should stop the red led from glowing. i am using a piece of thin cardboard with a white surface for testing and what i think is the cause of the error is the improper reflection from the surface. should i use some other thing if yes then what? and i dont know the part number of my IR receiver but it is like this-
[​IMG]

one more thing is that i am not sure of the connections of my 10K preset resistor which is like this-
[​IMG]


i have connected the top pin to the + input of the op-amp and the other two pins are one to 5V and other grounded. moreover i have not adjusted its value i have just connected it to the breadboard as it is.

In the above pot, when you use the two adjacent terminals, it gives the total value of the pot. If we use the top terminal along with any of the other two terminals, it gives a variable resistance which can be adjusted by moving the disc on the top.

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