psfales@ihlpl.ATT.COM (Peter Fales) (03/18/87)
I have been trying to come up with a simple method to receive IR signals such as those produced by a television set remote control. Since I don't need a great range (even a few inches would suffice), I thought it would be fairly simple, but I have come to the conclusion that there is something I don't know. In the March issue of Byte, Steve Ciarcia claims to the the job with nothing more than a photodiode in series with a resistor (cleaned up through a voltage comparator). But I can't make this work. I have tried several different IR photodiodes and phototransistors and in all cases the response time is too slow to accurately reproduce the square wave signal of the carrier (~40 KHz). One diode I have not tried yet is the TIL413 used in Ciarcia's article. Can I expect it to make that much difference? Anybody know where I can get one? Any other suggestions? As a result of the recent articles in Byte on this topic, I suspect that there may be others on the net who would be interested in any suggestions you may have. Thanks in advance, -- Peter Fales UUCP: ...ihnp4!ihlpl!psfales work: (312) 979-7784 AT&T Information Systems, IW 1Z-243 1100 E. Warrenville Rd., IL 60566
schumann@puff.WISC.EDU (Christopher Schumann) (03/23/87)
In article <1922@ihlpl.ATT.COM>, psfales@ihlpl.ATT.COM (Peter Fales) writes: > I have been trying to come up with a simple method to receive IR signals > such as those produced by a television set remote control. Since I don't > need a great range (even a few inches would suffice) > Thanks in advance, > Peter Fales Try a phototransistor. Radio Shack sells an IRED LED, Phototransistor pair for less than 3 dollars. If you use a large resistor (1 Megohm) you will get high sensitivity, but slow response. A smaller resistor will be less sensitive, but will be faster. Pick up RS's Mini-notebook on Opto-electronics for $1.49 for more help. Chris Schumann schumann@puff.wisc.edu
dennisg@fritz.UUCP (03/24/87)
In article <562@puff.WISC.EDU> schumann@puff.WISC.EDU (Christopher Schumann) writes: >Try a phototransistor. Radio Shack sells an IRED LED, Phototransistor >pair for less than 3 dollars. AAARGH! It's real handy to drop in to Radio Shack and pick up nifty parts for cheap, but I wish that they would get their act together. I bought said combo a couple of weeks ago, and just tried to use them last night. NO WORKIE until I found out that the data printed on the back of the blister pack gave the WRONG PIN-OUT FOR THE IR LED! Since the diode in question emits no light visible to my current set of peepers - even when the LED is installed properly - this took awhile to diagnose. Moral of the story: o always put a visible LED in series with the invisible one(s) o never trust the data on a blister pack
gene@cooper.UUCP (03/26/87)
In article <3972@fritz.UUCP>, dennisg@fritz.UUCP (Dennis Griesser) writes: > ... until I found out that the data printed on the back of > the blister pack gave the WRONG PIN-OUT FOR THE IR LED! What I do in most cases is not to trust such things like "short lead is the cathode, long lead is the anode" or any pictures of the case. Unless the LED is in a mondo-strango case, look through the plastic and match the leads with this drawing: -------(-===-)---- ---- | / | | | ------------/ | | | | | | | | | | | | ---|<--- | | C A Gene ...!ihnp4!philabs!phri!cooper!gene "Mourn for us, so pressed with fear. Chained and shackled, we all found Freedom choked, in dread we lived Since Tyrant was enthroned." - RJAH
levy@ttrdc.UUCP (03/29/87)
In article <801@cooper.UUCP>, gene@cooper.UUCP (Gene from EK Enterprises) writes: <In article <3972@fritz.UUCP>, dennisg@fritz.UUCP (Dennis Griesser) writes: << ... until I found out that the data printed on the back of << the blister pack gave the WRONG PIN-OUT FOR THE IR LED! <What I do in most cases is not to trust such things like "short lead is the <cathode, long lead is the anode" or any pictures of the case. Unless the <LED is in a mondo-strango case, look through the plastic and match the leads <with this drawing: < -------(-===-)---- ---- < | / | | < | ------------/ | | < | | | | < | | | | < | | ---|<--- | | < C A Why not just test with an ohmmeter (compare with the way the ohmmeter reads on a known-good garden-variety diode)? -- |------------dan levy------------| Path: ..!{akgua,homxb,ihnp4,ltuxa,mvuxa, | an engihacker @ | vax135}!ttrdc!ttrda!levy | at&t computer systems division | Disclaimer: try datclaimer. |--------skokie, illinois--------|
ornitz@kodak.UUCP (03/31/87)
In article <1640@ttrdc.UUCP> levy@ttrdc.UUCP (Daniel R. Levy) writes: > >Why not just test with an ohmmeter (compare with the way the ohmmeter reads >on a known-good garden-variety diode)? Light emitting diodes have a much higher forward drop than silicon or germanium diodes. Many ohmmeters have too low a voltage to indicate forward conduction with LED's. This is particularly true with digital multimeters which often have a special diode conduction setting to test silicon devices. The higher voltage found on some older VOM's can damage some LED's by exceeding their reverse breakdown ratings. I have found that on many meters set on a 10K scale, LED's show a slight conduction in one direction and virtually none in the other. This has usually been adequate to determine their polarity. Often this conduction is enhanced by exposing the LED to a bright light. ----------------- | ___ ________ | | | / / | | Barry L. Ornitz UUCP:...!rochester!kodak!ornitz | | / / | | Eastman Kodak Company | |< < K O D A K| | Eastman Chemicals Division Research Laboratories | | \ \ | | P. O. Box 1972 | |__\ \________| | Kingsport, TN 37662 615/229-4904 | | -----------------
dje@datacube.UUCP (04/01/87)
I generally mistrust LED markings; a disease I picked up from too many Poly-Packs (remember them?) purchases. To check polarity and operation at the same time, I use a 330 Ohm resistor in series hooked to a 5V supply (20 Ma). Proper polarity is indicated by the LED on. Dave Erickson ------------------------ Datacube Inc. 4 Dearborn Rd. Peabody, Ma 01960 617-535-6644 ------------------------ [ihnp4 | mirror]!datacube!dje
mouse@mcgill-vision.UUCP (04/02/87)
In article <801@cooper.UUCP>, gene@cooper.UUCP (Gene from EK Enterprises) writes: > In article <3972@fritz.UUCP>, dennisg@fritz.UUCP (Dennis Griesser) writes: >> ... until I found out that the data printed on the back of the >> blister pack gave the WRONG PIN-OUT FOR THE IR LED! > What I do in most cases is not to trust such things like "short lead > is the cathode, long lead is the anode" or any pictures of the case. > Unless the LED is in a mondo-strango case, look through the plastic > and match the leads with this drawing: > [drawing] Or you could always break down and use a dc ohmmeter....there are very few (probably none in working order) ohmmeters which will put out enough current to fry the LED, and similarly few which will put out enough voltage to fry it when reverse-biased. der Mouse Smart mailers: mouse@mcgill-vision.uucp USA: {ihnp4,decvax,akgua,utzoo,etc}!utcsri!musocs!mcgill-vision!mouse think!mosart!mcgill-vision!mouse ARPAnet: think!mosart!mcgill-vision!mouse@harvard.harvard.edu
zabetia@tiger.UUCP (04/04/87)
In article <100500005@datacube> dje@datacube.UUCP writes: > >I generally mistrust LED markings; a disease I picked up from too >many Poly-Packs (remember them?) purchases. To check polarity and >operation at the same time, I use a 330 Ohm resistor in series hooked >to a 5V supply (20 Ma). Proper polarity is indicated by the LED on. > > Dave Erickson Not if it's an Infrared LED. Unless your eyes were made differently. Try this: +5v ------\/\/\/\------>|--------- 0v 220ohms Normal LED The above circuit is set up. The LED lights up. Now take an LED that you are unsure of and put it in parallel with the first one. If the first on goes out or is dimmed, then chances are that the IR LED is emitting. Otherwise turn the test LED and try again. Mahboud Zabetian allegra! --\ zabetia@tiger.princeton.edu 232 Pyne Hall mhuxi! -----\ (609) 452-2285 Princeton University seismo! -----\ (609) 734-0246 Princeton, NJ 08544 attunix! ------ princeton!zabetia -- Mahboud Zabetian allegra! --\ zabetia@tiger.princeton.edu 232 Pyne Hall mhuxi! -----\ (609) 452-2285 Princeton University seismo! -----\ (609) 734-0246 Princeton, NJ 08544 attunix! ------ princeton!zabetia
dennisg@fritz.UUCP (04/04/87)
In article <100500005@datacube> dje@datacube.UUCP writes: >I generally mistrust LED markings; a disease I picked up from too >many Poly-Packs (remember them?) purchases. To check polarity and >operation at the same time, I use a 330 Ohm resistor in series hooked >to a 5V supply (20 Ma). Proper polarity is indicated by the LED on. Except that the LED in question was IR. Even when I got it connected properly, there was no emission that I could see. But I wasn't asking about how to find the correct polarity. No problem there. I was merely lamenting the fact that a large company like Radio Shack can sell thousands of IR LEDs (with backwards data sheets) to unsuspecting customers.