From baksh2@marshall.edu Tue 01 Oct 96 21:33:29 Relay-Version: ANU News - V6.1B10 04/18/95 OpenVMS AXP V6.2; site hobbit Path: marshall.edu!wvnvms!news.cais.net!news.mathworks.com!news-peer.gsl.net!news.gsl.net!portc01.blue.aol.com!newstf01.news.aol.com!newsbf02.news.aol.com!not-for-mail Newsgroups: comp.sys.hp48 Subject: Re: IR-Range Message-ID: <52jhao$96h@newsbf02.news.aol.com> From: pmaage@aol.com (Pmaage) Date: 28 Sep 1996 11:47:36 -0400 Sender: root@newsbf02.news.aol.com References: Organization: America Online, Inc. (1-800-827-6364) NNTP-Posting-Host: newsbf02.mail.aol.com X-Newsreader: AOL Offline Reader Lines: 47 Hi ! nv95half@linnea.asogy.stockholm.se schreibt: : Does anybody know how to icrease the rangelimit on the HP48s IR-port. There is also a web-page on this subject. (Incl. pics, large) http://www.contrib.andrew.cmu.edu/~drury/how2open.htm >Subject: Boost IR range! Easy hack! 12 feet+ range! >Date: 4 Dec 1995 05:08:00 GMT >From:gsmarlow@ouray.cudenver.edu (Scott Marlowe) >Organization: University of Colorado at Denver >Newsgroups:comp.sys.hp48 >FOUND IT! I found that freakin resistor that cripples your HP 48G/GX's >IR port receive function! If you have it open (see other files on that, >I'm not talking ANYONE through that one alone,) lay it face down on a >work table. With the bottom closest to you, you will see a small SMD >resistor labelled 224 right next to a 74HC00 IC (on the GX) or next to a >blank 14 pin spot on the G. This is a 220k resistor. With it in place, >and my IR port cover off, I measured a receive range with my JVC remote >of about 6" max for reliable programming under the REM34 program. >When I replaced this resistor with a 47k one (number will be 473, i.e. >47x10^3) My range is now at LEAST 12 feet. I was able to read the remote >from across my freaking kitchen!!! How very cool. >Tested the above with a JVC remote from 30 feet, and it worked GREAT. >Makes the REM program quite useful now, since you basically can bounce >signal off the wall and get a good read. >Popped the calc back open, and went from a 47k to a 100k resistor, and >still got 30+ feet. SOrry I couldn't test any longer distances, but my >living room and hallway are only so long... >I had tried a 200k resistor (isntead of the 220k built in) but got >the same dismal 6" max range with that. One thing I am worried about is >power consumption, but unless this is a non-linear increase in current, >I should be looking at no more than an increase of two times power >draw with half the resistance (100k vs 220k) so I'm willing to >be a guinea pig for a week or two.