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Does the IR LED in this circuit light just like the IR LED in a TV remote control?

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donrigor

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Does the IR LED in this circuit lights just like the IR led in a tV remote control?
I have tested it but the IR leds does not light when supplied with 5 volts.
It looks like it lights when it is supplied with 5 volts as circuit provides.
 

lm358+ir led

You show two IR LEDs in two different circuits. Which one are you asking about?

The receiver requires that you adjust the pot, R8, until this circuit is in the active region. Place a TV remove very close to D1 and then hold down a button that transmits continually, like the Volume UP button. Now, adjust R8 through its range watching for D3 to flash or flicker. If D3 is either always ON or always OFF, measure the voltages of pins 5,6 and 7 of the opamp U1 and report these to the board.
 

how to detect infrared led is working r not

If you want to test if the transmitter IR led is working, use some digital camera with live view, for example a cellphone camera is a good one. If you point the cellphone photo camera to the IR led and it is on, you will see it.

You can use this method to test any IR led (I'm not 100% sure about this), i've used this to check if a TV remote control is working or not.

I hope this can help.
Regards, Diego.
 

test infrared led on tv

[[You show two IR LEDs in two different circuits. Which one are you asking about?

The receiver requires that you adjust the pot, R8, until this circuit is in the active region. Place a TV remove very close to D1 and then hold down a button that transmits continually, like the Volume UP button. Now, adjust R8 through its range watching for D3 to flash or flicker. If D3 is either always ON or always OFF, measure the voltages of pins 5,6 and 7 of the opamp U1 and report these to the board.]]

When i adjust the potentiometer D3 lights permanently. My problem I don't know how D1 and D2 communicates, because as the circuit provides D1 transmits and D2 receives. How will i know that these two functions well?
 

show design of ir leds

At some point in the R8 adjustment range, the LED, D3, should go off. If it does not, then you have a wiring error or a defective component. Connect a voltmeter to pin 5 of the opamp. When you adjust R8, the voltage on pin 5 should vary from +5V to 0V. When the voltage on pin 5 is less than the voltage on pin 6, then the output pin 7 should go to 0V and the LED, D3, should be off.

You need to adjust R8 until D3 just turned from off to on. Then when IR light hits D1 it should cause D3 to go back off. This is because the IR light causes the voltage on pin 6 to increase.
 

amplifying the input to infrared leds

The PNP transistor at the input of the LM358 opamp goes high when the IR LED has no IR. Then the red LED is turned off.

I think the IR LED becomes a solar cell and produces a slightly negative voltage and current at pin 6 that will turn on the red LED.
 

how to test if an ir led is a transmitter

Cause D1 is reverse biased by LM358 input current, it's supposed to work rather as a photodiode. As far as I experienced, LEDs (as all semiconductor devices) have some photosensitivity. But they are very poor detectors, compared to a dedicated photodiode. Also using LM358 input current as diode bias is a rather dubious design to my opinion. The circuit may show meaningful operation under specific conditions. But if you can't get it working, better use a known good circuit instead of this artefact.
 

negative pin ir led

Thanks a lot Guys for the ideas!
Here i have modified the circuit, instead of using IR LEDs i use an LDR.

In the circuit, the D2 is permanently ON giving the LDR necessary light that makes D3 also ON and gives a reading of 3.5 Volts at pin 7 of LM358. When D2's light is interrupted (covering D2 with something) the reading on D3 becomes zero.

How do i make a pulse of 5 Volts making the ouput at pin 7 a 5 Volts instead of 3.5 volts?
Varying R8 to extreme left and extreme right doesn't produce a 5 volts at pin 7.
 

ir led d1

You had the collector and emitter of the PNP transistor connected backwards.
I fixed it.
Maybe it worked when connected backwards and maybe now the resistors will need to be changed for it to work.

The LDR was shown with its ground connection circling the schematic. I fixed it.

If you want the opamp to function in the reverse then swap the inputs pin 2 and pin 3.

You use the opamp as a comparator. Usually a comparator has some hysteresis added for a "snap-action". Without hysteresis the opamp will oscillate or it will amplify its own noise when the input voltage is at the threshold.
 

can a ir led work a 5 volts

The circuit should be able to detect a LDR resistance change. Unfortunately, a LDR has zero sensitivity at IR LED wavelength of 880 nm and 940 nm, it has a good matching with red and green LED however.
 

measure current of ir leds

donrigor said:
How do i make a pulse of 5 Volts making the ouput at pin 7 a 5 Volts instead of 3.5 volts?
Varying R8 to extreme left and extreme right doesn't produce a 5 volts at pin 7.
Click to expand...
Your circuit uses pin 1 of the opamp as its output, not pin 7.
The max output of the LM358 is about +3.8V with a 5V supply and no load. It is about +3.5V when the red LED is its load.
If it has a +6.5V supply then its output will go up to +5.0V.
 

infrared led circuits

Thanks for the information FvM!

Thanks a lot for that audioguru! i can output now a 5 volts.

Is this 5 volts enough to drive a counter?
 

ir transmitter led how many volts

The datasheet of the counter will show what voltages it needs for its input.
You forgot to say which counter (there are many different types).
 

ir led wavelength change

I'm going to use 74LS192 or 74LS163
 

advantage of lm358 in red led

I used 74LSxxx ICs about 31 years ago. Then I discovered CD4xxx Cmos ICs and have not used 74LSxxx ICs ever since. I use some 74HCxxxx Cmos ICs now.
 

74lsxxx series remote control circuit

I have read that CMOS is very sensitive. How did you use cmos 74HCXXX?
 

ir led transmitter to ldr

I have read that CMOS is very sensitive.
Click to expand...
Not very. They have effective ESD protection. It's O.K. to use 74LS, but 74HC is a good replacement. CD400X devices are particularly suited for slow logic circuits, less sensitive to interferences, and they have a comfortable supply voltage range.

But you may observe false counts when connecting a slow rising signal to a counter input. A schmitt-trigger (e.g. 74HC14) should be connected in between.
 

voltage ir led

Thanks for the idea FvM!

What does schmitt-trigger do to the counter?
 

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