On Thu, 2005-02-24 at 17:44 -0500, Dan Wilga wrote: > At 1:39 PM -0600 2/24/05, Robert Denier wrote: > >On Thu, 2005-02-24 at 14:12 -0500, Dan Wilga wrote: > >> I have two Dish 311 receivers. Rather than deal with an IR blaster > >> that either requires an ugly LED attached to the two units, or a > >> blaster that is subject to interference, I made a really cheap (about > >> $15) hardware modification that allows me to make a hardwired > >> connection directly from the 311's board to a small interface board > >> that sits inside my HTPC. The interface board is connected to a > >> serial header on the PC's motherboard. > > > >I certainly agree this is doable. Is there any reason to do this other > >than for cosmetic reasons? I remember someone was selling a simple tiny > >transmitter that connected with clear doublestick tape that was fairly > >unobtrusive. I wouldn't think having to physicaly modify the hardware > >would be worth it unless perhaps you ended with a simpler or more > >reliable setup software wise. I suppose if you needed this to look > >absolutely professional, it might be useful. > > It's partly for cosmetic reasons, but also for cost. If you don't go > with one big blaster transmitting to all devices, and instead opt for > the one LED attached to each receiver, then every time you add a > receiver the cost could go up. > > My hack consists of a board with a few resistors and an > opto-isolator.
I love those toys. My favorite were the ones that would handle about 20 amps AC and you could drive small motors or other power devices from a simple TTL signal source or any voltage between around 3-25 volts. Because of the optical isolation you could do it safely without being too concerned of accidently frying things. (I'm sure the one your using is much simpler/smaller.) I'd have to see your circuit to comment, but the addition of one ideally makes it impossible to fry your recievers components no matter what you plug into the new external connection. Good luck on your project. > Most serial ports could probably handle up to 6 or 8 > devices (using additional optos). Probably the most expensive parts > are the 1/8" stereo jacks; you need two per receiver, in order to > have a clean-looking installation with a jack on both ends of the > cable. > > I also scavenged the stereo cables to go from the PC to the > receivers, and a short length of ribbon cable to connect to the > motherboard's serial port connector. > > _______________________________________________ > mythtv-users mailing list > [email protected] > http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
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