Building (TV) IR Transmitter- Not Working

Short version:

Building a fun project SONY TV remote with timed MUTE keys.
Using new original UNO board( yes. Pin 3 and IR lib included)
Code loads and works fine.
When using any regular LED, the LED works fine

But when testing with IR LED and using live video from phone, its not firing.
When removing the resistor, I see a very wimpy firing.
Purchased a replacement batch of IR LEDs with no change. Then got a working SONY remote and substituted that IR LED. No change. (Yes- all polarity is correct)

Then I added a N222 transistor with an additional 5V. Still no change!
I saw comments on; but that is not helpful.
It seems as if the IR LED is not getting enough power to correctly fire.[/i]

I’ve spent the entire quarantine lock down trying to get this 15 min project to work.
Help ?

Perhaps we need the long version if it includes the code you're using and a schematic showing how everything is connected. That might help a lot.


Friend Slapstick:

Thank you for the reply. It appreciated.
I don’t have Frazzle (?) so working on a visio diagram to attach as Jpeg.
Code attached. Note actual delay times coded are shortened for testing.
To my no-nothing novice eye, it APPEARS there is not enough power to fire the IR LED.
Yet it seems to be working correctly when using a standard LED. Its a design right
off the internet per Using IR Remote Controls with the Arduino - YouTube but with the addition of a transistor
for additional power. The serial port also correctly corresponds to the program.

I look forward to any insight.


tv_Master1.ino (2.35 KB)

There’s no guarantee that a phone camera will register the ir light. They used to, years ago, but modern ones have ir filters built in.

If you connected the led to the Arduino pin without a resistor, you may have damaged the Arduino pin. If you connected the transistor base to the Arduino pin without a resistor, that could also have damaged it.

I don’t have Frazzle (?) so working on a visio diagram to attach as Jpeg.

You don’t need Frazzle (Fritzing perhaps?) or Visio. Just draw a schematic on paper and take a photo of it with your phone camera. The part around the transistor, LED and associated components are most important.

BTW you get more reliable IR results from a phone using the still camera rather than video though as PaulRB says it’s not guaranteed that you’ll see anything.


Ladies and Gentlemen of the Jury:

Confident the board is OK as again, this project works great with standard LED.
My phone camera shows clear and bright momentary light from the IR LED when testing against a good remote. It does not capture anything when testing with the Ardunio. I have tried 3 different IR LEDs. Nada.
This is supposedly a standard design (See Using IR Remote Controls with the Arduino - YouTube )
The function of an IR LED and a standard LED is pretty much the same so Im at a loss as to the malfunction.
Novice Diagram attached. I believe it to be correct but again… the projects works great with standard LED. So kindly forgive and copy-paste errors. Code previously attached.
The Arduino will measure a thousandth of a second, probably detect anti-mater, but can’t mute a TV?

Patiently awaiting your collective keen insight and technical wizardry.

PAULRB: I don’t like Frazzles- more of a Doritos guy.


Please learn to post your images so everyone can see them without having to download them.

Your transistor connections are all wrong.

Base to Arduino pin. 500K is 100 times too high.
Collector to the led cathode. Not the anode as you have drawn. What value of series resistor are you using there?
Emitter to 0V.

Those 10K connected to the buttons are not needed. Wire the buttons from the Arduino pin to ground and use INPUT_PULLUP. The input pins will read LOW when the buttons are pressed.

Once you have connected the transistor properly, build another Arduino project with just an IR receiver. Now you can see exactly what the IR LED is transmitting.

If you really have a 150K resistor in series with the LED then it's never going to work (and I'm not convinced that any standard LED works in that circuit either).



Thanks kindly for your reply's. I took a wrong turn by mislabeling the base. collector and emitter. Updated
diagram attached. Push buttons removed for clarity.

Please Note: As it stands now, there is a very low IR Pulse when viewed thru camera phone. ITS THERE... but very low when comparing the IR brightness against an actual TV remote. Not enough to be received by the TV. I believe its a power issue but don't know where. Again (Mr. Slapstick) I assure you the circuit has normal brilliance with a typical LED.
The LED is brilliant...I am not.

1 Like

That looks ok now (although we can't tell if you connected the led correctly).

Try running the blink sketch on the led, instead of sending ir codes. Does that look bright (through your phone)?