[WP-34s] How to install crystal and IR diode.pdf



#29

Link to pdf in dropbox

With the link above you'll find the first draft of 'How to install crystal and IR diode' on the WP-34s.

Marcus, Katie, and all the experts - please read it and tell me what has to be changed, so that I can make the corrected version available to 'the public' through the WP-34s team.

Thanks in advance for any suggestions.


#30

Nice work :-)

One remark: Page 7 reads a bit confusing. If I shorten the diode legs as much as possible, the longer leg is arbitrary. Is it meant this way by you?


#31

As far as I know the length of the legs only helps to determine which is the anode and which is the kathode. If you once have identified them, you can shorten them to your needs.

Katie, can you comment on this?

I will try to clear that up an rewrite it.


#32

For T-1 and T-1-3/4 LEDs, the lead next to the "flat spot" is the cathode (negative). In the schematic symbol, think of the triangle as an arrow. Current (flow from positive to negative, not electron flow) flows in the direction of the arrow, toward the flat.

Dale

#33

That's correct. The length of the leads (legs) has no significance other than to determine anode vs cathode. For almost all T1 (and T1-3/4) LED's the short leg is the cathode. For T1-3/4 LED's the flat spot on the bulb also indicates the cathode. T1 LED's often have no flat spot, or at least not one that's obvious, so lead length is important.

When in doubt (or after you've already cut down the legs) just use a multimeter with a diode check function. It'll quickly tell you which is which. The voltage drop on IR LED's is typically 1.0 to 1.5 volts well within the range of virtually all diode-checking multimeters. You can buy a multimeter with a diode check function for just a few dollars.


(Disclaimer: Heat sinking is very important in high-power LED applications and the length of the leads can be significant there, but this is a very low power application).

Edited: 3 May 2012, 6:04 p.m.

#34

This is amazing! As Randy of FixThatCalc.com can attest, I am hopeless with fine soldering (Randy has fixed some of my attempts!), so I would pay someone good money to do this for me ;)

L


#35

Quote:
This is amazing! As Randy of FixThatCalc.com can attest, I am hopeless with fine soldering (Randy has fixed some of my attempts!), so I would pay someone good money to do this for me ;)

Eric is making built up 34S's -- crystal and caps currently but I expect he'll add the IR diode eventually too. http://commerce.hpcalc.org/


- Pauli


#36

If you can get both printing and the stopwatch to be supported on the same ROM, sure. Ideally I am waiting for Harald to finish his board, as I feel that is a much better solution with the impending lack of availability of flash cables.

Hopefully the board will have IR, micro USB, and extra memory, and then we can continue to put the crystal and caps directly on the board.

Eric


#37

Harald should add some kind of ERASE logic to his board, e. g. by a small button reachable through the case. RESET is available. ERASE needs to be pulled high.

#38

The current printing image does both printing and the stopwatch.

We're not at all sure about the extra memory. The rework of the statistical distributions has freed up a lot of space and we've enough headroom for user libraries currently -- my unofficial aim here is 8 kb of libraries. Currently, the crystal + IR image has 8 3/4 kb for this (4480 steps). The other images have more -- the base image has 13 kb -- that's 6656 library steps, plus any steps in RAM and the backup region (a maximum of 927 in each or 1854 total). That's a maximum of 8510 steps of program on the device.


If I rework the normal quantile function yet again it will consume a hundred bytes or three.


- Pauli

#39

Eric, I just wanted to say that your price on a fully appointed unit with crystal is a bargain. I expect that IR diode and microUSB will push the price up, but justifiably so. I really look forward to what you will be able to offer us in the weeks or months to come. I have already broken a pin on one of Gene's cables, and I live in fear of doing likewise with my second one, no matter how gingerly I treat it, and not be able to fix or replace it. Having a unit with a USB interface will steady my hand and nerves! Put me down for one pimped-up WP34s as soon as you have them. Moreover, if you or anyone else here is willing to do the modification on existing units that we send to you (for crystal, caps, IR, microUSB, new and professionally applied overlay), I have no problem paying good money for that service if you would consider it. A set of WP34s's with robust USB connectors will give me years of pleasure. I'm willing to pay for that given I lack the skill with fine electronics and soldering to do it myself. I know you are busy, but I hope you could offer that option too.

Les

Edited: 6 May 2012, 12:42 p.m. after one or more responses were posted


#40

For each WP 34S Scientific Calculator that Eric sells, he donates a portion of the purchase price to the WP 34s developers.

Having provisioned one WP 34s myself, I can attest that the price for letting Eric do all the work is a bargain.

Mark Hardman

Edited: 5 May 2012, 8:33 p.m.


#41

Quote:

Having provisioned one WP 34s myself, I can attest that the price for letting Eric do all the work is a bargain.


True dat, as the young folk say.

#42

Quote:
Eric, I just wanted to say that your price on a fully appointed unit with crystal is a bargain. I expect that IR diode and microUSB will push the price up, but justifiably so. I really look forward to what you will be able to offer us in the weeks or months to come.

:

:

:

Put me down for one pimped-up WP34s as soon as you have them. Moreover, if you or anyone else here is willing to do the modification on existing units that we send to you (for crystal, caps, IR, microUSB, new and professionally applied overlay), I have no problem paying good money for that service if you would consider it.

:

:

:
Same here! I am all thumbs regarding the required DIY work here. I would ruin the main board in few minutes.

So please, count me in. I'm willing to buy a complete WP34Si (i=with IR module) ;) for the price it will require.

Looking forward for news.
#43

Alexander, I've committed your file to the doc directory in SVN. It's correct. :-)

Just an addition: The printer entries in P.FCN can be reached by pressing f EXIT (the little arrow). Outside of a catalogue, this little arrow acts as a keyboard shortcut to the [print]r X command - handy to print just the number in the display.


#44

Quote:
Alexander, I've committed your file to the doc directory in SVN. It's correct. :-)

I will eventually update my pdf according to the comments. Please download it again from the link in posting #1.

#45

For those in Germany (or Europe): I have all the parts here and can send them out for a small donation on our SF pages. I have 25 complete sets and need only a few for myself.


#46

Yes please Marcus. Especially as my 30b arrived today so I now have something to stick them in! (Although I will flash it (when my cable arrives) as a normal WP 34S initially and play around with it a bit before diving inside).

I'll send you an email through the Museum with my address.

Many thanks

James

#47

Nice write up, but I have a few questions/suggestions:

1) Aside from using much thinner wire (I recommend wire-wrap wire) at least use electrical tape if not heat-shrink tubing. Cellophane tape is a really bad choice.

2) The LED you specified is not the one I used. Do you get a similar range (about 50 cm)?

3) Using a 1/8 watt 390 ohm resistor instead of a 1/4 watt resistor will give you more space to more things around.

-Katie


#48

I get about 20cm of range with my setup.


#49

In that case, you might want to recommend using the IR emitter (LED) that I found:

Vishay TSAL4400

It's substantially better than any of the handful of other ones that I tried that were getting distances of around 20cm.


#50

Katie,

I've updated the document with your recommendation, mentioning your name. I hope that's ok?!?


#51

My name is not important but the LED is. The Vishay one uses a different, more efficient semiconductor material: GaAlAs/GaAs vs just GaAs in the Kingbright one that you used. That extra bit of aluminum in there makes a lot of difference at low power.

I've been experimenting with some green GaAlAs LEDS as low-level back light for LCD's and they work surprisingly well running with just 100ua. A couple of years of continuous back light from just 2 AA cells in an alarm clock I made. Perhaps the same would work in the WP34s, I need to play around with the LCD and a diffuser.

(no problem mentioning me in your write up)


#52

Katie,

when I bought the stuff I wasn't knowingly choosing but just trying to get parts that seemed to be closest in specs to what you used. Could you, for all of us who merely follow instructions without understanding what they are doing, maybe specify a range of specs that are important as opposed to specific products, that possibly are not available in all parts of the known world.


#53

Alexander, I have exactly the parts Katie has recommended. I ordered them at a local electronics store. It took them a week to get them.

#54

The specs for the LED that you used are fine on the surface of it. 940nm, 50 degree angle, etc.. So it was reasonable of you to try that LED, I had tried several T1-3/4 devices like this myself.

The TSAL4400 data sheet shows that at 2ma the radiant intensity is around 0.3 mw/sr. Kingbright gives a relative intensity vs current chart of the L-9343C with a typical intensity of 10mw/sr at 20ma. At 2ma you should expect an intensity of 1mw/sr, which is much better than the Vishay. But they also say that at a minimum you should only expect about 1.6mw/sr at 20ma, a big difference that would make the Vishay device the better choice. I don't trust the Kingbright data it's sketchy compared to the Vishay data.


Also I knew that GaAlAs performs very well at low current levels from my own experimenting with green LEDs so I thought that I'd try the Vishay one.


BTW, these Vishay parts are made in Germany according to
this page. They shouldn't be hard for your to buy.

Edited: 5 May 2012, 2:48 p.m.

#55

Nice document.

By no means a flaw or error, however on page 6: I've found it helps kinking the legs of the crystal so everything lies flat before soldering.


- Pauli

#56

excellent! and it's even done in LaTex for that vintage look :-)


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