Extra IR blasters for 9910 base ?

[lifeisfun]

Great !

Thanks

[zaphod7501]

First : I don't know if this will work with any brands other that Sony.
Second : the concept could work with any format that uses remote control data on a wired input.
Premise : In 1984 Sony used the identical chip from their remote control as a keyboard interface inside their TV to simplify wiring.
Requirement : they had to get data without a carrier wave.
Method : they connected the output of the chip to the IR receiver line through a very simple detector circuit.
Conclusion : to connect an IR remote signal to a wired input you have to run it through a detector circuit.
The Circuit : 5 resistors , one diode , one transistor , one mylar capacitor ; none of the parts is special at all. The value of one resistor and the capacitor might be critical as to the transmit frequency but might be broad enough to cover all the common one's in use.
My Limitation : I don't have a base station to experiment with but Tommy Tyler's been working with one and he would have to determine if adding a detector for a wired output was practical. Multiple wired outputs would need some isolation from each other.
I originally thought it would take a bandpass filter of some sort but the detector is very simple.

Tommy ?

[Tommy Tyler]

zaph and life,

If you're looking for just a voltage signal from an extender, the approach is different depending on whether it's a 9910 base station or a cone. With the cone, when you plug in an external LED (call it a blaster or stick-on if you prefer) it is pulsed at about 1/4 amp. So if you plug in about a 22 ohm resistor instead of an LED you should get a signal around 5 volts peak to peak. The problem is, that signal is floating, so you can't use it as a ground-referenced signal. As an alternative to AC coupling it, or using a voltage offset circuit, or any of that stuff, I'd suggest just using an opto isolator instead of a resistor. Put a 47 to 100 ohm resistor in series with the optosolator's diode to limit its current. (This assumes you don't mind weakening the output of the internal IR LEDs while you are doing this. If you need to keep the internal signal strength, plug in a 10 ohm resistor and apply the resulting 2.4 volt signal to an optoisolator through maybe about 47 ohms.) I haven't looked up the current rating of an isolator, and am not trying to give you a final design, just the general idea.

With the base station, the plug already provides a voltage signal because it's just in parallel across one of the IR LEDs. But again, that 1.5 volt signal is floating and not referenced to anything, because it's out in the middle of the string. You still might be able to squeak by with an isolator and small resistor. If you need ideas on how to use the small, floating signal, let me know what you are trying to do with it.

[Tommy Tyler]

Oh, and another thing. A good way to demodulate an IR carrier that doesn't depend on frequency is to just use a re-triggerable one-shot whose period is set to just slightly longer than the period of the lowest frequency you want to demodulate. For example, say you want to go as low a 25KHz carriers. That's a period of 40 us, so shoot for a one-shot period of say 50 us.

[bercy46]

Ok, got that problem fixed by attachin 150 ohm resistor on the Xantech IR input. Works great now.

I'm really stupid when it comes to electronics, and english is not my mother tongue.

Could you (or someone else) post a diagram or picture of this setup ? And adding detailed comments would be great too

Thanks.