[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.





More information about the mythtv-users mailing list