eastman@tsbmacgw.nrl.navy.mil (04/30/91)
I live in an apartment with a couple of other guys, and for reasons of safety to my stereo, I keep it in my room with a set of speakers in the living room. What I would like to build is a device that I could point my remote at, that would have some sort of phototransistor receptor and driver circuitry, which would then drive an IR emitting diode in the same room as the stereo. Does anyone out there have any ideas/comments? Inparticular what kind of wire should I use from the receiver to the emitter, what kind of photodiode and IR emitter should I use, have any articles been written on this, etc... respond by email or post. thanks, Curt Eastman
csmith@plains.NoDak.edu (Carl Smith) (04/30/91)
In article <216@ra.nrl-cmf.UUCP> eastman@tsb.nrl.navy.mil writes: >I live in an apartment with a couple of other guys, and for reasons of safety >to my stereo, I keep it in my room with a set of speakers in the living room. > >What I would like to build is a device that I could point my remote at, that >would have some sort of phototransistor receptor and driver circuitry, which >would then drive an IR emitting diode in the same room as the stereo. > >thanks, > >Curt Eastman I recently built such a device in a couple hours, using that GP1U52X infared reciever/demodulator that Radio Shack sells. It recieves a 40 KHz infared signal, and outputs a logic high when present, and a logic low when not. It has 3 pins. Power, ground, and ttl out. I inverted the ttl out with a not gate, and used this active low signal to toggle a 555 timer on and off. The 555 is set in astable mode at 40 KHz, using a circuit like that shown on page 7 of the 555 timer IC Circuit book that Radio Shack sells, but the connection from pin four (reset) is removed from Vcc and connected to the output of the inverter. This is how the IR Reciever and inverter toggle the 555 on and off in pulses of 40 KHz. The output of the 555 is connected through a 47 ohm current limiting resistor in series with an IR LED. This IR LED can be placed wherever you please, by putting it on a long piece of ordinary speaker wire. This works fine with some remotes and not with others. It works with my RCA VCR, but not with the remote for my stereo. I suspect this is because of the automatic gain control and limiter built into the IR reciever. In the abscence of an IR signal the reciever cranks up it's gain looking for a weak signal. When the remote's IR hits it, it saturates the reciever for the first couple pulses, until the automatic gain control adjusts. If whatever is recieving your remote signals can handle this, all is well. Otherwise this won't work, and some modification would need to be made... Have Fun Carl D. Smith Jr. Senior EEE student, North Dakota State University. (Yes, 3 e's. We get an extra e at NDSU.)