Extra IR blasters for 9910 base ?

lifeisfun · Post by **lifeisfun** » Mon Jan 17, 2005 4:43 pm

Can I add extra IR blasters to the base of 9910 ?
I would like to have about 4 in total
Would this fry the inside parts ?
If so should I first disconnect the on board blasters ? ( I don't use them anyway only the remote one)

Thanks

lifeisfun · Post by **lifeisfun** » Sat Jan 29, 2005 5:54 am

Am I the only one interested to do this ?

zaphod7501 · Post by **zaphod7501** » Sat Jan 29, 2005 2:01 pm

I don't have this particular blaster but I do have a couple of others that I use (RCA and Zenith --- both send and receive each other's signals so I send simultaneous command to two different locations -- my A/V equipment is located at various places around the house) and they use 2 wire connections to the blaster.

I measured the output voltage with no blaster is attached at about 1.5 volts DC,and started writing a treatise on the reasons why it would be hard to do without some sort of electronic kit project. Then I grabbed my camcorder (any type of digital imager would work) and saw that there were 3 emitters within the base station. When the blaster is plugged in , one of the internal LEDs goes off. You could dismount the internal LEDs and connect them to wires and put them anywhere (within reason) that you want them. All would probably have to be connected for any to work (they are probably in series). You could do it ugly with wires just coming out the back or bottom or neatly by using miniature phone jacks and plugs like the original blaster. If you matched the original setup then each external LED you plugged in would turn off one internal LED.

This assumes that the 9910 works exactly the same as mine. I would grab a digital camera or any camcorder and have a "look" at the output of the 9910 base station both with the blaster connected and disconnected..

lifeisfun · Post by **lifeisfun** » Sat Jan 29, 2005 5:45 pm

Thanks for reply !
There is four IR LEDs in series and the one external is parallel to 2nd internal. I got couple of those ultra small external stick on blasters and tried to connect them but the refuse to work

I presume they are designed for 12V systems and inside the 9910 receiver I measured 2V only ....

zaphod7501 · Post by **zaphod7501** » Sat Jan 29, 2005 8:45 pm

Here are three questions that might help us get started on the right track.
Did the internal LED turn off when the external one was plugged in?
Is one of the 4 visible light (an indicator rather than IR?)?
Is the original blaster 2 wire or 3 wire? The add-ons?

Maybe I should have written out the big long explanation I was writing and added it as a footnote but here are some of the points I was going to make. This is very generalized. Accross any LED you will only see about 2 volts because the junctions act like a Zener diode when forward biased and clamps the voltage (actually it's a waveform but you would need an oscilloscope to view it). If you connect two or more in parallel only the one with the lowest threshold will turn on (and clamp the voltage), the voltage will be now too low to turn the other one on. Only perfectly matched diodes will run in parallel. In other words if you have an LED which turns on at 1.8 volts and one that turns on at 1.3 volts ; when the 1.3 turns on , only 1.3 volts will be present accross the LED and the 1.8 won't turn on because it need 1.8 and you only have 1.3 present.

If the polarity is wrong the diode will turn off and do nothing. Your add-ons might not be wired the same as the original, or they might have internal resistors added.

The internal diodes have no bias (or dropping) resistors (to control current) because they will use just one resistor that controls current for the entire series, while your add-ons might have them (and so won't work). My blaster has no resistors but turns off, and takes the place of, the internal LED when you plug it in.

If you wired your add-on blasters in series with each other then 2 volts could never turn them on. In series they would need at least 4 volts. In parallel with internal diodes only lower threshold LEDs would turn on.

If your add-ons do have current control resistors built in then they might work by connecting them from the source signal to ground (in parallel with the entire internal series) This would increse the load on the drive circut which may or may not make any difference depending upon it's design.

The turn on voltages vary because an LED is composed of many internal junctions , the number of which determine the threshold , IIRC.

You will probably have to substitute the external diodes for the internal diodes - not add on ; or turn off the internals as you add the externals if you are using diodes with no current control resistors.

It's really hard to be certain without good schematics. The basic way of turning on a diode is standard but there are many ways to accomplish the task.

lifeisfun · Post by **lifeisfun** » Sat Jan 29, 2005 9:52 pm

The polarity was ok since there was slight red light on impulse

Did the internal LED turn off when the external one was plugged in?
No the original external is paralel to 2nd in line on board ( there is 4 ofthem in chain - series)

Is one of the 4 visible light (an indicator rather than IR?)?
No there is 5th separate Red LED on board for that

Is the original blaster 2 wire or 3 wire? The add-ons?
2 wire and my add-ons 2 wire as well

I checked the original ext LED with ohm meter and it gives readin only half what I get from those I got

- that must be the problem ....

zaphod7501 · Post by **zaphod7501** » Sun Jan 30, 2005 12:03 am

Well , there are few things you could try. You could connect your extra blasters accross 2 diodes instead of one to increase the voltage available (requires soldering ). You could unsolder the original LEDs and attach them to long wires extending them from the case. You could build a little driver circuit triggered from the original blaster jack to drive lots of LEDs. (this might require some electronic knowledge , equipment , parts , research ,time , desire)

I don't know if there is any way to do your modifications without some rewiring and I don't know your level of elictrical ability so it's hard to advise ; and of course you don't want to kill the base in the process of experimenting.

While you might be able to take the original LEDs and mount them remotely (requires some soldering and attention to detail but no electronic knowledge) I don't think you could substitute your new blasters for the originals without some design work.

lifeisfun · Post by **lifeisfun** » Sun Jan 30, 2005 7:08 am

I tried that

There is transistor > resistor > feeding the diodes
When I measure the voltage before the resistor it's 4V
Unfortunately still not enough

What I like about the new external blasters is the ultra small size
and very thin leads. I Who designed the blaster included with the unit
didn't spent much time on it...
Looks horrible and the LED head sticks out of the 2" x 1/2" x 1/4" body.

Tommy Tyler · Post by **Tommy Tyler** » Sun Jan 30, 2005 12:55 pm

lifeisfun,

If you'll give me the brand name, model number, and any other descriptive info you have for the IR extender I'll see if I might have a schematic.

Tommy

lifeisfun · Post by **lifeisfun** » Sun Jan 30, 2005 1:53 pm

It is URC9910 RF receiver/IR emitter

Thanks Tommy

Tommy Tyler · Post by **Tommy Tyler** » Mon Jan 31, 2005 8:20 am

Sorry, I don't have any info on the 9910 at all. You probably don't want to do without it for a few days, but if you get desperate enough you can always mail the base unit to me and I'll be glad to reverse-engineer it and tell you all the ways to add additional blasters.

Tommy

zaphod7501 · Post by **zaphod7501** » Mon Jan 31, 2005 9:01 am

Hi Tommy , I don't have much time right now (work , you know) but he might be able to buid a simple driver box with a wall-wart transformer , a transistor , a few resistors and some jacks , that would plug into the existing blaster jack and drive as many extra blasters as he wanted.

MaskedMan · Post by **MaskedMan** » Mon Jan 31, 2005 3:27 pm

Tommy Tyler wrote:Sorry, I don't have any info on the 9910 at all. You probably don't want to do without it for a few days, but if you get desperate enough you can always mail the base unit to me and I'll be glad to reverse-engineer it and tell you all the ways to add additional blasters.

Tommy

Tommy, I have 8 of the basestations sitting in box, if you want one, Ill be glad to ship you one.

lifeisfun · Post by **lifeisfun** » Mon Jan 31, 2005 3:34 pm

I have XANTECH MODEL 789-44 CONNECTING BLOCK
would it be possible to use the URC box and feed the Xantech
on the IR receiver input ?

Tommy Tyler · Post by **Tommy Tyler** » Mon Jan 31, 2005 3:37 pm

Hey, Kemosabe,

I'll send the info by PM.

Tommy