ramesh@whuts.UUCP (RAMESH) (02/09/88)
Could somebody on the net suggest to me the appropriate photodiode and IR LED to use for IR remote control systems. (The same type as used on remote TVs, VCRs etc.) I tried some Radio Shack Phototransistors but were too slow to detect the modulation from my TV remote. Thanks for any help. N. Ramesh @ ATT Bell Labs, Whippany, NJ -- N. Ramesh
psfales@ihlpe.ATT.COM (Pete Fales) (02/12/88)
In article <3719@whuts.UUCP>, ramesh@whuts.UUCP (RAMESH) writes: > Could somebody on the net suggest to me the appropriate photodiode and > IR LED to use for IR remote control systems. (The same type as used on > remote TVs, VCRs etc.) > > I tried some Radio Shack Phototransistors but were too slow to > detect the modulation from my TV remote. > Thanks for any help. I went through this some process about a year ago, and got several helpful responses from the net (about speeding up bipolar phototransistors). However, nobody had the right answer which I eventually stumbled upon myself: Most bipolar photdiodes and phototransistors have switching speeds on the order of tens of microseconds. Since the IR remotes use carrier frequencies with clock periods of around 25 microseconds, this does not work too well. You need to use a PIN (Positive-Intrinsic-Negative) photodiode. Radio Shack does not sell any. I used an SFH205 from Active Electronics, Framingham MA. The Texas Instruments TIL413 has been used for similar projects in Byte magazine. -- Peter Fales UUCP: ...ihnp4!ihlpe!psfales work: (312) 979-7784 AT&T Information Systems, IW 1Z-243 1100 E. Warrenville Rd., IL 60566