[vdr] Which DVB-T

Marko Mäkelä marko.makela at hut.fi
Tue Feb 21 23:15:15 CET 2006


On Thu, Jan 26, 2006 at 10:09:52AM +0200, Marko Mäkelä wrote:
> On Thu, Jan 26, 2006 at 12:38:44PM +1000, Torgeir Veimo wrote:
> > On Thu, 2006-01-26 at 00:55 +0200, Marko Mäkelä wrote:
> > > Apparently, the bundled IR receiver module does not work with 3.3 volt
> > > supply.  So, the Hauppauge guys chose to drop the 5 volts from the PCI
> > > bus by R47 (49.9 ohms) to something like 4.1 volts, so that the cheap
> > > IR receiver will still work and not kill the I/O pin on the cx23882.
> > > 
> > > Next step for me is to get a 3.3 volt capable IR receiver and connect
> > > my hardware to the 3.3Vaux and PME# lines on the PCI bus. 
> > 
> > Do you know any drop-in replacement modules? I've always though the
> > bundled one had too low sensitivity as well.
> 
> I'm planning to get a Vishay TSOP31236
> (http://www.vishay.com/ir-receiver-modules/), which has a wide supply voltage
> range of 2.7 to 5.5 volts.  I'm planning to solder a cord directly on its
> pins and to apply heat shrink tube, so that I can avoid building a case.

I wasn't able to source these, and I'm not sure of the modulation frequency.
38 kHz might be closer.

I got an Everlight IRM-3638N3 today.  I could also have got a Sharp GP1UD
series receiver.

When I first connected the receiver, I was severely disappointed, because
it would not work reliably from 20 cm distance.  The output was 2,15 V
at the operating voltage 3,20 V (I modified the card to use 3.3Vaux),
while it should be at least 2,7 V at 3,0 V.  I connected it to the newer
Nova-T PCI 90002 that I hadn't modified in any way.  There, the output
was steady 3,3 V, no matter if I pressed any button on the remote control.

Well, I thought, I'll attach my wake-on-remote circuit
(http://www.iki.fi/~msmakela/electronics/worc5/) to the Nova-T anyway,
and I'll buy another receiver later.  After I finished the soldering work,
I decided to give it another try.  With that circuit, the output of the
receiver is connected to an input of an ATtiny12 microcontroller, and an
output of the ATtiny12 is connected to the IR signal input of the cx23882.
The output was very close to Vcc, and the range was very good (at least
10 meters).

I'll publish an updated version of the wake-on-remote circuit as soon as
I get a new board for the prototype manufactured.  I'm now trying to use
PME# as the wake signal instead of Wake-on-LAN, but for some reason
(probably bad soldering) it doesn't work.  The advantage of PME# over
Wake-on-LAN is that all modifications can be made on the PCI card.

In other words, I'm afraid you can't simply replace the receiver with
a better one.  You will also have to rewire the power supply of the
receiver.  To do that, desolder R47 and solder a +3.3V wire from the
PCI slot to the top pad.  The bottom pad goes to a +5V supply from
the PCI slot.  Of course, you'd be doing that at your own risk.

	Marko



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