Re: LIRC on Raspberry Pi3B+

On 2/4/19 3:27 PM, [email protected] wrote:
> Hi Alec and Bengt
> 
> Thanks to;
> - Bengt's hints & some similar pointers given at in the Raspberry forum
> - and also realizing that my iphone, which camera previously picked up 
> the the IR-light, seem not to show this anymore
> I could move forward.
Nice that I was able to help.
> 
> As much as this may sound like BS, it's true: it worked all along!
> My Iphones could not show the IR-LED activity (I have 2 and none picked 
> up on the IR)

Despite of the "folklore wisdom", not all smartphone cameras react to 
IR. Strictly speaking, a camera that does not react to IR is the better 
camera, since a camera is there ("normally") to see what the human eye 
sees. Here is an interesting thread that discusses these issues: 
http://www.hifi-remote.com/forums/viewtopic.php?t=100859
  (I am Barf there).

 > and also I had for some reason changed my setup to be as
> mentioned in the instructions - collector attached to 3.3V.
> As much as this may be right way, it gives a very weak IR-pulse => the 
> TV did not pick them up.
> 
> Using an older phone & camera showed me there was in fact an IR-pulse 
> but weak as h-l

200 ohms is a very high collector resistor. You will get approximately

(3.3 - 1.4 - 0.2)/200 = 0.0085 A = 8.5mA

which WILL give a faily short range. For the maximal ratings, see the 
data sheet for the IR lead. On top of my head, at least 100mA should be 
possible for continuous operation. For very short operation, you can go 
into the Ampere range. This is OK since the normal IR protocols does not 
send continuously for very long.

While at it, I would recommend using a MOSFET, 2N7000 or BS170 
https://en.wikipedia.org/wiki/2N7000 instead of the NPN. You can then 
leave out the base (gate) resistor, reducing the component count.

Greetz,

Bengt