HP Forum Archive 18

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Op-Amp Gain and Offset Design for the HP-67 Message #1 Posted by Stefan Vorkoetter on 4 Dec 2008, 9:02 p.m. I've posted yet another program for the HP-67/97 to my web site. This one is for designing analog gain and offset stages using a single op-amp. Program listing, usage instructions, and background info can all be found at http://www.stefanv.com/calculators/hp67_offset_gain.html. Enjoy, Stefan PS. I've also put some effort into creating presentable images of the magnetic card, in the style of pre-recorded cards from HP. I'd be curious to know if these look right in browsers other than IE and Mozilla.

Re: Op-Amp Gain and Offset Design for the HP-67 Message #2 Posted by Etienne Victoria on 5 Dec 2008, 1:07 a.m., in response to message #1 by Stefan Vorkoetter Hello Stefan, I do not have the knowledge to test your program but the magnetic card is a beautiful job. It looks perfect on Safari 3.2.1 Cheers! Etienne

Re: Op-Amp Gain and Offset Design for the HP-67 Message #3 Posted by Prabhu Bhooplapur on 5 Dec 2008, 8:05 a.m., in response to message #1 by Stefan Vorkoetter Hi Stefan, This is nostalgic for me - reminding good old days of analog design. There was a time when any electronic circuit was conceived with op-amps. The magnetic card has come out well. Have you tried the emulators of HP67 and HP97 from Michael O'Shea at limpidfox.com? The emulators also give good documentation of program listing. Best regards, Prabhu Bhooplapur

Re: Op-Amp Gain and Offset Design for the HP-67 Message #4 Posted by Stefan Vorkoetter on 5 Dec 2008, 1:44 p.m., in response to message #3 by Prabhu Bhooplapur Quote: There was a time when any electronic circuit was conceived with op-amps. Many still are. Even with the trend to do signal processing digitally, analog stages are still needed to get the data into the digital system, and often to get it back out as well. I still design a lot of hobby projects using op-amps (many are posted on my web site), and I sometimes get comments like, "you could have done this using the [PIC/ATMEL/...] single-chip computer". I think that in a way, analog design is to digital design like using a slide rule or RPN calculator is to using a computer. To do analog design, you really need to understand the problem. Stefan Vorkoetter

Re: Op-Amp Gain and Offset Design for the HP-67 Message #5 Posted by Tom Mathes on 5 Dec 2008, 3:36 p.m., in response to message #4 by Stefan Vorkoetter Quote: Many still are. Even with the trend to do signal processing digitally, analog stages are still needed to get the data into the digital system, and often to get it back out as well. I still design a lot of hobby projects using op-amps (many are posted on my web site), and I sometimes get comments like, "you could have done this using the [PIC/ATMEL/...] single-chip computer". I think that in a way, analog design is to digital design like using a slide rule or RPN calculator is to using a computer. To do analog design, you really need to understand the problem. Stefan Vorkoetter I'm one of those people who still do pure analog design and do it for a living (I design power management ICs). There still is a place in the electronics food chain for our expertise. I think.

Re: Op-Amp Gain and Offset Design for the HP-67 Message #6 Posted by Garth Wilson on 5 Dec 2008, 5:10 p.m., in response to message #5 by Tom Mathes I expect that op-amp sales are continuing to increase as op amps are reaching performance levels that could not have been imagined 20 years ago. They will always be faster than digital, and for many applications, remain more economical. And, as Stefan pointed out, digital needs op amps to handle analog signals. I still design lots of op amps into our products, with no end in sight.

Re: Op-Amp Gain and Offset Design for the HP-67 Message #7 Posted by Tom Mathes on 5 Dec 2008, 10:57 a.m., in response to message #1 by Stefan Vorkoetter Quote: I've posted yet another program for the HP-67/97 to my web site. This one is for designing analog gain and offset stages using a single op-amp. Program listing, usage instructions, and background info can all be found at http://www.stefanv.com/calculators/hp67_offset_gain.html. Enjoy, Stefan PS. I've also put some effort into creating presentable images of the magnetic card, in the style of pre-recorded cards from HP. I'd be curious to know if these look right in browsers other than IE and Mozilla. Now if the program can be modified to determine where that hidden pole is in the unity gain buffer for an IC I'm designing it'll be perfect! ;-) Tom

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