[mythtv-users] CIR... Where to purchase? (also an aside re DC SdCv)

Mike Thomas mt3 at pfw.demon.co.uk
Tue Mar 4 22:10:05 UTC 2014

On Tue, 4 Mar 2014 07:37:49 -0600
Leif Pihl <leif at pihl.us> wrote:
> Gents: 
> I have an Intel DH77KC motherboard, equipped with C.I.R. (Consumer
> Infra Red). The connections are illustrated at labels "S" and "T" in
> the diagram shown at this URL:
> http://www.intel.com/support/motherboards/desktop/dh77kc/sb/CS-033204.htm
> The "T" connector MAY have five pins,  and  the "S" connector does
> have seven pins. 
> I need to purchase a C.I.R. (Consumer Infra Red) Receiver and
> Emitter, as discussed on page 27 of the PDF shown at this link:
> http://www.wit.ru/download/DH77KCspec.pdf 
> The problem is, I have no idea where to find a pair of "C.I.R."s.  
> ***  	Can anyone provide a hint and/or link to the relevant
> part(s)? 

Dear Leif,

You don't need an emitter unless you are attempting to send infra-red
signals from your computer to another device, for instance a set-top

Reading the document you pointed to, it is clear to me you'll need to
solder up a cable with a 0.1" PCB header on one end and an infra-red
receiver chip on the other. You'll need to take anti-static precautions
whilst making up the cable and house the chip in a little box so it
doesn't get rogered when it falls on the carpet. You can get a
selection of chips from any decent electronic component suppliers. I
use http://rswww.com/ and http://www.farnell.co.uk/ frequently. They
both stock lots of different LEDs and photodiodes, each with slightly
different response spectra and they both have offices around the world.

Without reading the Microsoft specification it is unclear whether an
ordinary photodiode will do, so unless you're adept at designing your
own pre-amp for your photodiode, what you really want for a receiver is
a combined photodiode, high dynamic range amplifier, high-pass filter
and line driver. There are plenty of chips which do that on those web
sites. However, from my experience of trying those very same chips, you
may find you get nowhere.

So I think the rider to your question is "Can anyone find a part that
works?" What I'm saying is don't spend too much money on them because it
might not work for you.

I have a Sharp telly and I bought a Sharp remote control receiver chip
with all the filtering and whatnot. Like you, I imagined the receiver
chip would be all fine and dandy with that telly in the room. But would
it work with other remote controls? Would it buggery.

The problem was the signal from the remote control became completely
blotted out by the infra-red from the telly's own back-light.
Theoretically with a programmable remote control it should be possible
to have it send its signals in the gaps when the telly isn't
illuminating the room, but try as I might I couldn't teach my remote
controls to do that.

Compact Fluorescent Lamps also give off tons of infra-red, so even if
you find a remote control which can transmit its signals in the moments
when your telly isn't lighting up the room, it's still likely to get
stuffed by your room lighting. Frankly I'm amazed that any infra-red
devices work these days, but maybe it's something peculiar to my house.

I know they work for most people, but I ended up using bluetooth. The
casual reader might like to know that I found this device to be the
most reliable of the remote controls I tried:


It's still on sale. The manufacturer calls it a 'Focus RM-518 Remote
Control'. It's a bluetooth keyboard and trackerball in the shape of a
remote control. It comes with a USB dongle with a flashing activity
light and appears to the computer as a HID. It'll work with windows and
linux (at least), and it has a 30ft+ range in my experience. It's based
upon the lc-power chipset. There can be several remote controls and
dongles within earshot of each other and they don't garble each other's

A driver for this chip is present in the kernel (it's a common keyboard
driver chip), but it maps the keys incorrectly for this remote control,
so I wrote a kernel patch which will map the keys properly. Combined
with the proper .Xmodmap it is possible to use seamlessly both inside
and outside MythTV. I can supply the files upon request.

> -----
> BTW, perhaps I should mention that I'm also shopping for a 5V to 3.3V
> DC Stepdown Converter. I have two burnt out (old style) AirPort
> Expresses, so I have some interest in doing the project described at
> URL:
> http://evolver.fm/2013/06/06/airplay-on-the-highway-put-apple-airport-express-in-your-car/ 
> That page has this link:
> http://www.ebay.com/itm/281058278731?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
> for one such DC Stepdown Converter.  
> Any chance to purchase both items from the same company would be
> icing on the cake. ----- 

Maplin sell lots of power conversion thingummies and adapters as do the
other companies I listed.

> Tanks... 

What? They're in Kiev already?

> LP
> .


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