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Introduction & HP-50g printing issue
09-17-2014, 04:05 AM
Post: #1
Introduction & HP-50g printing issue
Hello gang, I thought I'd introduce myself. I'm John DeArmond, a retired nuclear engineer, now occupied most of the time as the Chief Engineer at fluxeon.com, a company that manufactures induction heaters. Oh, and I'm an HP calculator nut. I have my original 45 and 97, a fairly complete 41 set, an original model 48 that never got used and now an HP-50g.

My current obsession is making the 50g and my HP IR printer actually work together. I've done quite a bit of work in that area and posted it over in comp.sys.hp48. Joe Horn suggested that I might also want to come over here and start posting about my work.

Simply put, I AM going to make my 50g print from several feet away. I've spent a great deal of time analyzing the current setup, the IrDA transceiver module, the circuitry, the module programming (the calc programs the module to low power mode upon power up.) I'll post the details of that work in another post if there is interest.

I have removed a cathode resistor from the LED that limited power and I've defeated the power-on low power programming. The result is that I can print from couple of inches of separation instead of with the lenses in contact plus a hope and a prayer.

Clearly not enough, I'm looking at one of two basic approaches. 1) making a tiny daughterboard to hold and translate the pin-outs of a higher power IrDA module and 2) dispense wtih the IrDA module and design a board to use a high powered 5mm IR LED, probably losing the IR receive function in the process. The receive function is useless since holding two calculators in contact with each other will not result in communications ( have 2 50gs).

I think that option 2) is going to be the ultimate solution. Of the IrDA modules stocked by Digikey and Mouser, the brightest one is only a few db more than what I have now. That leaves conventional IR emitters, of which there are some very bright ones stocked by both distributors.

I have several questionss.

* Is the IR receive functionality important to you?

* is there much interest with 50g owners regarding functioning printing?

* If there is interest, is there enough that I should design the solution to be reproducable by others or should I simply do a one-off hack for myself.

* Is there sufficient interest in printing that you'd either buy a kit to modify your calculator with or you'd send your calculator to me for modification?

Finally, any suggestions, tips, pointers to previous work, etc., would be most welcome.

Thanks
John
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09-17-2014, 07:38 AM
Post: #2
RE: Introduction & HP-50g printing issue
John,

my view is that it would be the best solution to make a small dongle which attaches either to the serial or the USB port instead of modifying the hardware. This dongle could have its own power supply and therefore use a high power IR emitter.
Most people would probably not want to open their beloved calculators and a plug-in solution is also more versatile (a similar thingy had been developed for the HP49). For example a serial-IR/RedEye interface could also be used with other calculators like the HP 40, 49. It would also be worth to consider bidirectional communication using SIR/IrDA like the HP 48 did.

I do not think that such a device would be a big commercial success, but making the hard- and software available (maybe in kit form or preassembled) to enthusiasts would surely be a good idea.

Regards, Martin
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09-19-2014, 12:42 AM
Post: #3
RE: Introduction & HP-50g printing issue
(09-17-2014 07:38 AM)Martin Hepperle Wrote:  John,

my view is that it would be the best solution to make a small dongle which attaches either to the serial or the USB port instead of modifying the hardware. This dongle could have its own power supply and therefore use a high power IR emitter.

Martin, you're talking about turning this into a major hardware and software project as opposed to my simple modification scheme. A major project with little chance of return. Electronics is my vocation, my avocation and my hobby but that's just too much.

(09-17-2014 07:38 AM)Martin Hepperle Wrote:  Most people would probably not want to open their beloved calculators and a plug-in solution is also more versatile (a similar thingy had been developed for the HP49). For example a serial-IR/RedEye interface could also be used with other calculators like the HP 40, 49. It would also be worth to consider bidirectional communication using SIR/IrDA like the HP 48 did.

While my 45 and 95 will probably fall into the category of "beloved", my 50g certainly will not. It's cheaply made, the firmware is incomplete and it has inadequate battery life. Anyone thinking about loving a 50g should look inside at the soldering. Some of the worst ROHS I've ever seen. One can almost hear the tin whiskers growing! No one should plan on passing a 50g down as an heirloom!

To me, my 50g is a tool to make my work more efficient. And like any tool, if it doesn't suit the job at hand, modify it til it does. And when it breaks, toss it and get another. I picked up 2 spares from Amazon for about $50 each, just in case my hacking damages my current unit and in case HP discontinues the 50g. I certainly don't want a Prime.

(09-17-2014 07:38 AM)Martin Hepperle Wrote:  I do not think that such a device would be a big commercial success, but making the hard- and software available (maybe in kit form or preassembled) to enthusiasts would surely be a good idea.

Yes, that's probably a good idea but not for me. I'm going to do the minimum possible to make the calculator do what it should have done out of the box and that is, print to the IR printer from a comfortable distance away. I'm certainly not going to start a major hardware and software development project nor force-feed myself sysRPL or maybe even ASM to redirect the print job out the USB port just so I can generate a tape from my calculations that I can tape into my engineer's log instead of hand-transcribing the data.

I plan on the printer sitting on the shelf above my lab bench, always on and ready to print. After I finish a run of my custom software, I plan on looking up, aiming the calculator in the general direction of the printer and pressing the "print" soft key.

We kinda got off on a tangent so let me try to reel the discussion back in. I would like to know

*) how many people are interested in having a useful print function?

*) How many people think the now-non-functional IR receive function is worth saving?

*) How many people would be interested in an assembled and tested kit board that they could install?

*) How many people would find a service that modifies their calculators useful?

*) Finally, how many people would be interested in printing if there was available a small box or dongle that would plug into an HP parallel or USB port and print RedEye? This last question concerns the future when the supply of HP IR printers runs out.

Thanks,
John
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09-20-2014, 06:18 AM
Post: #4
RE: Introduction & HP-50g printing issue
(09-19-2014 12:42 AM)neonjohn Wrote:  We kinda got off on a tangent so let me try to reel the discussion back in. I would like to know

*) how many people are interested in having a useful print function?

*) How many people think the now-non-functional IR receive function is worth saving?

*) How many people would be interested in an assembled and tested kit board that they could install?

*) How many people would find a service that modifies their calculators useful?

*) Finally, how many people would be interested in printing if there was available a small box or dongle that would plug into an HP parallel or USB port and print RedEye? This last question concerns the future when the supply of HP IR printers runs out.

Thanks,
John
1. I am interested
2. If you can make it functional, the do so. I never like to go backward even 1 mm. Ever. Ego numquam recede.
3. Definitely.
4. Possibly, I'd need more details.
5. There are only a finite number of them? Smile Well, OK, then. Yes.

Tom L
Cui bono?
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