Re: Connect a wire to an IR receiver?

> > I would like to control multiple devices with my computer. On the
> > transmitters page[0] it shows how to use the serial port, so I was
> > thinking to build something like this:
> >
> > DTR >---(1N4148)---(R)---> device's IR cathode
> >
> > 1/ would it work?
>
> You have to be a bit more precise. Most IR controlled consumer
> electronic do not have a "cathode" (an IR diode?) but a demodulating
> chip, TSOPxxx or similar. This removes the modulation from the signal.
> So most likely what you propose would not work. How to eliminate the
> modulation from the sent signal has been discussed here before, for
> example here:
> https://sourceforge.net/p/lirc/mailman/lirc-list/?viewmonth=202003&viewday=20

My bad, I misunderstood how an IR receiver worked.
I thought it only was an IR diode that transmitted the modulated
signal to some chip for its demodulation.

Does the serial driver support non-modulated signals?

> > 2/ is it dangerous for my PC or my device(s)? I plan to connect 3 on my computer
>
> I would recommend deploying opto couplers, like 4N26, to achieve
> galvanic isolation. Connect the catode of the IR diode (pin 2) to ground
> of the PC, the anode (1) through a resistor (1k?) to the sender signal,
> the emitter (4) to the ground of the receiver, leave base (6)
> unconnected, the collector (5) to where the TSOP was, with a pull-up
> (10k?) to Vcc.

Thanks! I guess if I use the USB port for the Vcc it will lose the
galvanic isolation?
Also can I connect the collector (5) to multiple TSOP or each device
must be isolated from each other?

> > [0] https://www.lirc.org/transmitters.html
>
> Be aware that this is a 20 year old document. How many 20 year old IT
> documents are still "valid"? (OK, you asked us, so there is hope for you
> ;-)).

The documentation is always up-to-date right? :p