I need to connect a RCA DRD515RB to an IR emitter in 2 ways?

1) To drive the DSS box itself. This box has the IR receiver in the middle of the menu button keypad. So if you glue the emitter to the IR sensor, you have glued it to the button.

2) The box can drive a VCR with its own IR emitter. I would like to send that IR signal back into the IR system so that I only need one IR emitter glued to the VCR. One suggestion was to glue the VCR emitter to an IR receiver for the xantech system. I was wondering if there was a simple opto-isolator solution, but have been unable to find info on the control signals used on the Xantech IR bus.

I have two suggestions.

First, call the tech guys at Xantech. They are good and will help you figure this out if there is a reasonably simple way to do it. Tell them I told you to call.

The second suggestion is just to try it. It may be as simple as this, which looks a heck of a lot worse on paper than it does in practice:

The LED output from the RCA goes to the optoisolator's input diode. Of course, be sure the polarity is right or everything will grind to a halt.

Use the Xantech bus's power so you are working in the correct voltage range. The guys at Xantech recommend the 782 because the 781Cs occasionally take a dump but the 782s do not. Every time a 781C goes bad, you have saved a bit of money for the customer but caused a free service call (while making less money on the system to begin with). I never use 781Cs any more.

Assuming the opto output is an NPN (I think they all are), connect a 390 ohm current limiting resistor from the +12V to the output collector. This means that when the transistor is on, a max of about 30 mA will flow out of the emitter.
Connect a low current diode (e.g. 1N4148) to the output emitter to keep current from going back into the opto output transistor from the bus.
Connect a resistor from the output emitter to ground so the output is pulled down to zero when the transistor is off. This should be high enough so that the voltage dividing effect of it and the 390 ohm resistor does not pull down the maximum output voltage and drain current that would otherwise go to the output. I would try 1K to begin with, although a higher resistance might be needed.


When I first read your post I thought this was a frivolous idea, but the more I think about how wrong it looks to have two LEDs on a piece, the more it makes perfect sense. I prefer putting the LEDs inside the equipment, but that is more frivolous than your idea!

Ernie

Thanx for the info. I was looking for a description of a simple opto-isolator circuit for this problem. I'll take the description and work out a schematic.

Any ideas on how to flash the IR for the RCA itself? It seems like going inside the unit is the most reliable given the location of the IR receiver. I was considering trying a high-output IR emitter stuck to the shelf near the box, but I'm concerned about reliability.

What opto-coupler would you recommend (part number 4N22?)

I've had quite a lot of success placing the flashers inside the units. You don't have to worry about them falling off, etc. and it really doesn't take all that long. Just make sure you test the unit before opening the case as the warranty may be voided when you do open it. Depending on the IR system you are using, you could treat the IR output of the sat as a sensor input on your IR system, thus only using one flasher on your VCR.

I just got done doing what G_Gifford stated but with a couple twists. I took a pair of side cutters and cut the red plastic off the flasher. If you look real close it has a seam. Cut on that and the lenses will pop off. My DTC-100 may be like your RCA. When I took the case off and got to the front panel I noticed the eye is directly behind the menu button as well but the menu button has an offest arm that actually pushes in a button on the circuit board at about the 7 o'clock position. There for it gives the appearance of being in the center of the unit while having the eye in the center. I just found something to wire tie the emmiter to so it would stay in place over the eye. I also put the internal emiiters in my JVC vcr and a Pioneer 850 receiver. It took a couple hours to do it nice and wire tie everything off. I was also able the route the wire out of the case where the plugs go by bending a little metal. I didn't have to drill one hole on any of them.