What is the correct way to connect a single IR emitter to 2 IR outputs? In this situation, it will be a Xantech 283-00 Blink-IR connected to both a Crestron CP2 and a Xantech 789-44. I'm guessing it's not as simple as just paralleling them, that there's probably a resistor or diode involved somewhere.

Any help appreciated.

Run the Crestron output INTO the 789-44, then the Emmitter into the 789-44.

Deb,

Connect the negative side of your flasher directly to the ground connection on each unit.

On the positive terminal of each unit, attach a diode.... connect the other end of the two diodes together and connect the postive lead of your emitter to that junction.

If you hook the diodes up backward, the only problem you will have is that it will not work.... just reverse them in that case.

The purpose for the diodes and to allow current flow from either unit through the emitter through its diode while the other unit effectively blocks a path back into the non-sending device.

No big deal to do. The diodes will lower the voltage to the emitter a little but, but I have not had a problem with that in an application.

You will often see lots of answers to questions such as the one you posed. The reason there have only been two answers, and I (who tend to go on and on about how to do stuff) have nothing to add is that the two answers above pretty much cover everything. Heck, I'm only responding to make sure you know that it has been covered and to get your subject back to the top of the list.

I appreciate the help, and am glad there are only 2 answers. Could've easily turned into a 3-page discussion.

After 10 years in the business, you'd think I'd know the answer, but it's a situation I'd never come across and didn't want to waste time troubleshooting after the fact. I went with the diode solution since I happened to have some (I'd done it before using 3 separate wallwarts to trigger a single power controller so it made sense). Worked first try, which is always the goal.

Impaqt & Warren, thanks much.

Just curious, are the diodes really necessry? I know it's good practice but does the unused driver care if it sees an incoming IR signal?

Let the discussion begin!!
I agree with Thon I don't think that the diodes are necessary. Xantech connecting block's use resistors to buffer the outputs

The only question is whether or not the Crestron or the Xantech block care if they see an IR pulse coming in through the out door. Probably not, but it beats troubleshooting after the fact.

No need for extra diodes. IR emitters used by Xantech, Crestron and almost everyone else are infra red liight emitting diodes (IR-LEDs). That's why you always have to watch their polarity during installation.
Wire them in series (positive side of first emitter to signal out/tip, negative side of first emitter to positive side of second emitter, negative side of second emitter to ground/sleeve.
Have done it often and works always.

WJS,

I think they're talking about 2 drivers driving the same emitter, although you are correct for one driver driving 2 emitters.

Depending on the circuitry, it's *possible* two different brand components can drive the same emitter. However, it's also possible that something *could* be damaged by direct connection (without diodes), due to differences in internal resistance, ground paths, voltages, etc. You won't know for sure, unless you either try it and see, or examine schematics for each device.

Bottom line -- why take the risk, when diodes are only a few cents?

Thank you Tony,

Many times blocking diodes are not really necessary, but, since many will read these posts, and there is no way to know what different types of equipment someone will try to apply it to, I felt it responsible to stay on the safe side.

Bottom line is that, if you use the blocking diodes, your equipment is safe from any backfeeding, and will work.

Without the diodes, it might work, might work intermittently, might not work, or might damage something. You have to rememeber.... it is not Infrafed going through the wires, but DC voltage pulses representing the pattern of the IR.

No sense taking the chance. Diodes are too cheap and too easy to use.

What's the specs for the proper diode for this purpose? (ie: please provide enough info in order for me to purchase them -- I don't know much about diodes)

Thanks

The diode used is not all that critical since you are dealing with a very low voltage and current.

Most any silicon diode rated at 1 amp or more would be fine... the LED current draw is well below that range.

Radio Shack part # 276-1144 will work fine if you don't want to go looking anywhere else.

You can buy them much cheaper by looking around, but if you only need a couple that probably isn't worth your time.

In more formal terms, a 1N914 germanium diode, also called a switching diode, are the little glass-encapsulated ones; the little black ones would most commonly be a 1N4001, 1N4002, 1N4003 (these are all the same basic silicon diode with progressively higher reverse voltage specs, which is irrelevant since we use voltages less than will blow any of them) light power diodes.

As long as they are just plain diodes, probably any one will do because the voltages and currents we deal with are very small in the world of diodes.