Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

IR sensor, cannot make it working

Status
Not open for further replies.
If the IR emitter works and you still don´t get the signal, try to increase R2 up to 100k-220k or you should add supplementary circuitry for the sensor. A PNP transistor might help. See details:
 

Attachments

  • IR circuit_2.JPG
    IR circuit_2.JPG
    24.9 KB · Views: 101
  • IR circuit.JPG
    IR circuit.JPG
    26.3 KB · Views: 103
The emitter is working
100K version i have checked , i will now check with PNP version
 
Last edited:

The two infrared components used in this circuit must be ‘band’ compatible, so generated IR light by diode and the respond of photodiode to the same wavelength.
Also need to consider operating point of the receiver input circuit is rather dependent on ambient day-light levels and the value of R2 may need to be adjusted a little to ensure a voltage of between 0.5 V and 1 V on the collector of T1 when no signal is being received.
 

I would start with an analog ohmmeter and check how the detector diode responds to IR light from the LED. You will also see if and how much the surrounding light affects the detector diode. Often, an IR filter is needed to suppress the stray-light effects. Your circuits can work also without the PNP or NPN transistors; you can adjust opamp gain for the best results.
 

The receiver using now have ohms range at 0.9M ohms for visible light and its 60 to 180 Ohms in the case of IR radiations, using a higher resistor decreases the range of IR, I am using 1K and it gets a range of some 5cm only



jiripolivka said:
Often, an IR filter is needed to suppress the stray-light effects.
Click to expand...
so by using TSOP1738 , we can attain that , isnt it ?,
Any good schematic for the same ?
 
Last edited:

The IR modules are designed to receive pulsed IR rays.TSOP 1738 will not responds to continuous IR rays without pulsations, accepts only 38kHz. Need to change the transmitter side also. Use IC555 to generate 38khz signal and connect an infrared LED to its output.
 

I cant use a pulsed, then I should go with the IR diode and photodiode
 

Why? What's the limitation imposed for this circuit?
 

jiripolivka said:
I would start with an analog ohmmeter and check how the detector diode responds to IR light from the LED. You will also see if and how much the surrounding light affects the detector diode. Often, an IR filter is needed to suppress the stray-light effects. Your circuits can work also without the PNP or NPN transistors; you can adjust opamp gain for the best results.
Click to expand...
The receiver using now have ohms range at 0.9M ohms for visible light and its 60 to 180 Ohms in the case of IR radiations, using a higher resistor decreases the range of IR ? I am using 1K and it gets a range of some 5cm only
How can i implement IR filter here ? , what component should I add ?

---------- Post added at 03:08 ---------- Previous post was at 02:59 ----------
mister_rf said:
Why? What's the limitation imposed for this circuit?
Click to expand...
I am making an obstacle detector, by making a pulse circuit, the whole circuit becomes huge, because I have to use some 8 such sensor in the project
if I can make a circuit such that it can just make on and off an LED accoding to the IR falling on it can be more helpful for the project.

The pulsed switching makes the coding also tedius
 
Last edited:

You mention coding. A pulsed transmitter can be made with the 10F200 from Microchip plus a small driving mosfet (if needed)(see:PIC10F200 ). It is hard to envision anything much smaller compared to your original plan of using discrete components. The receivers are highly integrated and very small. If you don't want to do the coding of an MCU, transmitters can be made using multivibrators. Working circuits for such have been posted on this forum recently.

The biggest advantage is that the the pulsed systems work well in various lighting conditions. A simple IRED transmitter and phototransistor or other detector will have poor range and be quite susceptible to interference.

Maybe it is time to rethink the requirement for a non-pulsed system.

John
 
  • Like
Reactions: varunme

    varunme

    varunme

    Points: 2
    Helpful Answer Positive Rating
jpanhalt said:
You mention coding. A pulsed transmitter can be made with the 10F200 from Microchip plus a small driving mosfet (if needed)(see:PIC10F200 ). It is hard to envision anything much smaller compared to your original plan of using discrete components. The receivers are highly integrated and very small. If you don't want to do the coding of an MCU, transmitters can be made using multivibrators. Working circuits for such have been posted on this forum recently.

The biggest advantage is that the the pulsed systems work well in various lighting conditions. A simple IRED transmitter and phototransistor or other detector will have poor range and be quite susceptible to interference.

Maybe it is time to rethink the requirement for a non-pulsed system.

John
Click to expand...
Thanks for nice suggestion
yes for my prototyping, I am using this non pulsed system, and the time for giving the working model is now too less, so i have to go with the available one
the circuit i have posted is working isnt it ?
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top