universal remote with headphone jack

Hello, I am trying to create a universal remote with my android. I have been trying to light a remote led using my android headphone jack, but I have had no success. I am running ARA Smart Rem on my android to produce the signal. I pressed the button on the remote and I can see the light on my webcam, but I can not see the light when I power it with the headphone jack. I connect a stripped headphone plug with a pair of with alligator clips to the led. The media volume is all the way up. How do I get the light to light up?

sort by: active | newest | oldest

Have you got the polarity of the LED the right way round? The long leg is positive, to short one is negative.

Have you got a resistor wired in series with the LED? If not, you may have blown the LED. The resistor value should be about 330ohms.

Have you wired up to the right bits of the headphone jack and have you tested that the headphone plug wires are not broken. I've tried to salvage some old headphone wires before but there was not current when I connected whatever I connected across it - its worth checking that it works.

Hope this helps,


jbaker22 (author)  theredbryophyte1 year ago

The polarity is right. I double checked by swapping it. I do not have
resistor. I believe the problem may be because it is not getting enough
power. I can only get 1.5 vac on my craftsman 82022. That is full volume
from my computer, and .45vac from my phone. I plugged the audio into an amplifier and got 1vac, but no light. The ambient vac form the air is
.1 vac. The headphone jack is fine. I can play audio since it is a 3.5mm
to component, and it is 0 ohms. I have wired it to left right, and both
with the negative staying negative. Am I not getting enough voltage?

I'm not sure that you can rely on the Craftsman multimeter to tell you the true voltage. True - the voltage is alternating but it doesn't alternate regularly like AC. [do you know whether the voltage ever goes negative]

If you've got access to an oscilloscope then you could measure the peak voltage. The voltage needed for IR LEDs seems to be in the range of 1.2V to 1.5V. You could also try with a visible red LED to test if the phone side of it is working. It also might be an idea to check that the IR LED is still working: connect it up to 5V (USB if you don't have an Arduino or similar) with a 330ohm resistor through it and check with your webcam - you definitely need the resistor with 5V.

jbaker22 (author)  theredbryophyte1 year ago

I hooked the audio to my tv, then hooked the led to the speaker. The led was not destroyed. I saw it led work, but the tv did not turn off. I guess there is no winning here.

It might be sending the wrong code to the TV. If you have an Arduino you could see what code it is sending: Arduino-Infrared-Remote-tutorial. If you do, you'll want to be using the code in Step 4 so you can see the side sent in step 5. Compare the code for your phone remote and the code from the original remote.

Do you have a light on you TV which flashes when you use the remote. If so, is it flashing when you use the phone remote?

jbaker22 (author)  theredbryophyte1 year ago

I do not have a flashing light on the tv. If I do read the code with my arduino, what do I do with the code. I know the code is wrong.