[mythtv-users] USB to Serial Adapter cable for IR Blaster?
Gary Buhrmaster
gary_buhrmaster at usa.net
Wed Mar 17 02:49:21 UTC 2010
Kirk Bocek wrote:
> Gary Buhrmaster wrote:
> > To make things cleaner in the long run I plan to use some
> > optoisolators to run the signals from the blaster to the
> > DTA units thanks to the ideas from others that have done
> > the same thing from tivo's to the DTAs.
>
> Gary, if you've got some information you can share on optoisolators, please
> do. This came up as I was getting my Motoroa DTA100s working. They come with
> an "IR In" jack and a wired IR receiver so you can put them in remote
> locations. It was mentioned that with an optoisolator you could connect the
> DTA directly to an IR emitter port. It would be a cleaner way to avoid
> cross-talk between multiple emitters than by using black electrical tape.
Note that I have *NOT* yet built this (was waiting
for some free time to show up to verify the ir blaster
pinouts and to verify the blaster has internal current
limiting so I do not have to add in a resister to the
blaster wires), but from information at:
http://forums.tivo.com/pe/action/forums/displaythread?postID=10435840&ie=x#e10435840
and http://www.nteinc.com/specs/3000to3099/pdf/nte3041.pdf
this is what I *plan* to build. The result should be a
cable with a "bump" in the middle for the optoisolator.
(ASCII art schematic follows. Fixed font required
for viewing)
NTE3041
+------+
--------+ +-------+1 6+ +--------+ +--------
////////| | | | | | |////////
////////+=========*=== +--+2 5+--+ ===*===*=====+////////
////////| | | | | | |////////
--------+ +--------+ +3 4+---------------+ +--------
+------+
Mono plug Stereo plug
to blaster to DTA
There are also some cheaper (by component costs) mosfet
designs around, but since I am doing only a few, this
seems cheap enough, and I liked the idea of full isolation.
Here is the mosfet design for a tivo (which probably works
with many ir blasters; a 10 second look at the circuit looks
like it should work): http://grayeng.net/TiVotoComcast.htm
The individual also sells pre-assembled units on ebay.
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