IR sensor, cannot make it working
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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:
The emitter is working
100K version i have checked , i will now check with PNP version
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
so by using TSOP1738 , we can attain that , isnt it ?,
Any good schematic for the same ?
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?
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 ----------
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
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
You may adapt to use only one transmitter circuit for all IR LEDs.
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 ?