38 KHz IR xmtr
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From: hamilton on 23 May 2010 10:27 On 5/23/2010 1:20 AM, lektric.dan(a)gmail.com wrote: > On May 22, 4:54 pm, "Tim Williams"<tmoran...(a)charter.net> wrote: >> Interesting question. >> >> Remote controls are all based on microcontrollers (possibly 4 bit, mask >> programmed), so they don't need it. > > Well, yeah, but these aren't used by hobbiests either. That's what > I'm thinking of. There are no products built for "hobbiests". Just hobbyists using standard products. I just don't understand what your asking for. http://www.lirc.org/ hamilton > > > Since this is true of the general >> marketplace, I guess that might answer your question. > > No, not really. How big is the hobbiest market? Since no one's > actually *bothered* to make one of these purpose-specific chips, it's > hard to say what the penetration into the commercial market would be > as well. > >> You can make your own from a 555, R and C, so it's not hard otherwise. >> > But I thought that's what the whole idea behind the PIC was. Now you > want me to create an analog device using about six (or so) discrete > parts when one digital part would do it? I specificly remember Don > Lancaster writing in one of his columns years back about how he would > never use a 555 again. Well, Don, am I right? Is this the equivalent > of a 3-pin regulator, or just wishful thinking? (and you can be an > extremely harsh but extremely realistic critic)
From: whit3rd on 24 May 2010 17:32 On May 22, 2:29 pm, "lektric....(a)gmail.com" <lektric....(a)gmail.com> wrote: > Why are there no one-chip 38KHz oscillators for remote control >[ hobbyists? ] The combined functions of 38 kHz oscillator, NAND gate, and LED driver, is presumably what you're asking for? Gated CMOS oscillators (crystal clocks with an 'enable' pin) come close, but that 38 kHz frequency isn't a standard in that form factor. Any old oscillator you can trim, and two diodes and a transistor, is all that's required. Commercial remotes use higher frequency clocks and divide down, and that's how a PIC solution would likely be designed, too. For best current to the LED, the PIC solution still wants a transistor.
From: Glenn Gundlach on 24 May 2010 23:30 On May 24, 8:23 pm, Glenn Gundlach <stratu...(a)yahoo.com> wrote: Sorry about that Digikey link. Try this one http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=PNA4602M-ND They have MANY more types. G²
From: Tony on 25 May 2010 10:32 lektric.dan(a)gmail.com wrote: > On May 22, 5:38 pm, David Eather <eat...(a)tpg.com.au> wrote: >> On 23/05/2010 7:29 AM, lektric....(a)gmail.com wrote: >> >>> Why are there no one-chip 38KHz oscillators for remote control >>> hobbiests? How much does the cheapest PIC cost? All one would need >>> are 3 leads - power/ground/modulation-enable/output. Power driving >>> could be left to the end user. I'm supprised no one makes these. >> Have a look at this - page 94 and 95 might be of interest >> >> http://www.rev-ed.co.uk/docs/picaxe_manual2.pdf > > That's a little beyond what I was looking for, but nice to know. I > wasn't looking for commands, just the modulation of the signal. In > playing around with photodetector circuits recently, it would have > been really nice to be able to use the IR modulation detectors > available instead of just a simple phototransister. Although there's > no actual data going over the beam, its a lot easier to pick out of > the background. Why don't you just use an old remote control? Ok some of them tend to have large gaps between repeats so might reduce your latency slightly as you have to allow these. If you were really lucky you might find a remote with a test mode that outputs carrier wave only. -- Tony
From: JosephKK on 29 May 2010 02:34
On Sat, 22 May 2010 16:54:41 -0500, "Tim Williams" <tmoranwms(a)charter.net> wrote: >Interesting question. > >Remote controls are all based on microcontrollers (possibly 4 bit, mask >programmed), so they don't need it. Since this is true of the general >marketplace, I guess that might answer your question. > >You can make your own from a 555, R and C, so it's not hard otherwise. > >Tim Actually they do make them. They are just seriously hard to find for the uninitiated. |