DIY Infrared range disappointing, TV left wanting more...

I have constructed what I like to call a circuit...and maybe therein lies the problem. The folks over at have been gracious enough to post the schematic to the hardware that they also sell in the store. I have followed this as close as I could, however I have gone astray in 3 areas.

PROBLEM The unit works, my television turns off/on but only if I am within 3ft from it. The website states that their device works at over 10 meters (18+ miles right?...I'm kidding, just a little Imperial system humor).

3 known differences
1. R5 calls for 1k2, I don't have one...I used a 1k and a 330 in series.
2. C4 and C5 call for 10uF, I used 10uF for both. However, one of them is 16v and the other is 50v.
3. I don't have a 6v battery, so I have tried 5v, 9v, and 12v with the same results in each case.

Would any of these 3 mistakes cause my range to be 10x less than the site claims? 

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Rowen275 years ago
may or may not have anything to do with your problem, but to get the correct voltage (6v), connect four 1.5v batteries (AA's or AAA's, aught to do it) in series.
Re-design5 years ago
You need a lens to focus the led.
Since there can't be any DC in the LED, try making the 100R resistor into 10R


I'd be considering exactly what IR led you're using also - different lenses will have different angles/power ratings.
earthtown (author)  frollard5 years ago
The IR LEDs High Output 5mm:
forward voltage 1.2V
forward current 100mA
viewing angle to 1/2 intensity 45 degree

I also have some wide(r) angle LEDs, would adding 2 of them in the same polarity configuration (resulting in a total of 4 LEDs) change the output?

I'm looking about the the house for a parabolic mirror to try and implement as well...somebody's flashlight is getting cannibalized.
The tighter the beam the better the throw, the wider the beam, the easier it is to aim.

...those seem pretty typical - I'd be thinking you're not allowing enough current through them, but I'm not entirely sure how the circuit works - looks like it amplifies the audio into a fake digital signal.
earthtown (author)  steveastrouk5 years ago
I gave the 10R a run, improved range by about a foot...progress is progress right?
In that case, the 100nF cap is vital. We've proved that the current limiting resistor itself isn't doing much, so the impedance of the 10uF's must be significant.