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DIY Case for NP-25
02-08-2015, 03:31 AM (This post was last modified: 03-30-2015 02:09 AM by Sanjeev Visvanatha.)
Post: #1
DIY Case for NP-25
The NP-25 V3 is a little gem. Thank you Chris Chung for making it happen.

I know the intent of the NP-25 was to be worn on a lanyard, perhaps as a conference goodie. I wanted a neat package to go with it. Here it is:

[Image: IMG_4558.JPG]

[Image: IMG_4559.JPG]

[Image: IMG_4557.JPG]

[Image: IMG_4553.JPG]


Materials List:

1. Business Card Clear PVC Box 12 Mil (2 1/4" x 3 11/16" x 5/8" ). These hold 10 business cards, or one NP-25.

2. Packing Foam Sheet (approx 6mm thick). I did not purchase it for this purpose, it was lying around in my trinket drawer. You will need something to make up the thickness in the case so the calculator does not move.

Procedure:

1. The NP-25 has raised LED and switches. The top side of the business card box requires rectangular cutouts so these can poke out. This allows the keys to be directly behind the top surface of the case.

2. The back side of the calculator is uneven in height. I placed a piece of the foam above and below the coin cell, and then another longer piece the full length of the case. The piece of packing foam under the display has a cutout in it to accommodate the chips mounted on the back,

Next Steps:

I would like to put a keyboard overlay on the case, with a key's primary and shifted function(s) presented as on the real hardware.

Since the NP-25 is a 3-in-1 calculator, my plan is to use a transparent pocket on the front to hold an overlay. This overlay would be of the calculator you want to use. A second transparent pocket on the backside would house the remaining 2 overlays, with a NP-25 quick reference card visible on the back.

I found transparent business card pouches at the Dollar Store for this purpose. They are adhesive, so they would be placed on the front and back sides of the case.

My shortcoming is that I do not trust my handywork in creating a nice overlay. If there are any interested parties, please make yourselves known.

Finally, I have more of the plastic cases, if anyone is interested in trying this. There was a minimum order of 10, so I have some more. You would have to supply your own foam and cutting expertise. I also have the transparent pockets I plan to use to hold the overlays.

-- Sanjeev Visvanatha
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02-08-2015, 02:37 PM (This post was last modified: 02-08-2015 06:44 PM by rprosperi.)
Post: #2
RE: DIY Case for NP-25
(02-08-2015 03:31 AM)Sanjeev Visvanatha Wrote:  Finally, I have more of the plastic cases, if anyone is interested in trying this. There was a minimum order of 10, so I have some more. You would have to supply your own foam and cutting expertise. I also have the transparent pockets I plan to use to hold the overlays.

Very cool Sanjeev - DIY overlays for a DIY case for a DIY calculator project. What an amazingly creative group here!

I'd like to get 2 of the cases, contact me via PM or email to arrange.

Also, please post some shots of the box cover without the calc installed to see the holes cut, etc.

Cool.

--Bob Prosperi
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02-08-2015, 06:36 PM (This post was last modified: 03-30-2015 02:11 AM by Sanjeev Visvanatha.)
Post: #3
RE: DIY Case for NP-25
(02-08-2015 02:37 PM)rprosperi Wrote:  I'd like to get 2 of the cases, contact me via PM or email to arrange.
I will send you a note in a day or two. I will have to pick up some CD mailers, and will let you know when I am ready to send it. (I'll also send a photo of something I am picking up tomorrow!)

(02-08-2015 02:37 PM)rprosperi Wrote:  Also, please post some shots of the box cover without the calc installed to see the wholes cut, etc.

Here are a few more shots showing the packing foam, and the case.

[Image: IMG_4568.JPG]

There are 3 cutouts in the case. One for the LED, one for the power switch, and one for the Program/Run button (only because a nearby component sticks up).

The packing foam is in 3 pieces. One piece is the exact size of the case, and is placed at the bottom. One piece goes below the battery, and piece one goes above the battery. The one above the battery has a cutout for the chips on the backside of the calculator.

[Image: IMG_4567.JPG]

[Image: IMG_4569.JPG]

The business card pouch I mentioned is something like this:

[Image: 51HfsaIRwwL.jpg]

I plan on putting one on the front of the case for the overlay currently in use, and one at the back of the case to store the other two overlays and a NP-25 reference card.

Anyone wanting to create 3 overlays to suit this design will get free case materials with postage paid!

-- Sanjeev Visvanatha
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02-08-2015, 06:44 PM
Post: #4
RE: DIY Case for NP-25
(02-08-2015 06:36 PM)Sanjeev Visvanatha Wrote:  Here are a few more shots showing the packing foam, and the case.

There are 3 cutouts in the case. One for the LED, one for the power switch, and one for the Program/Run button (only because a nearby component sticks up).

The packing foam is in 3 pieces. One piece is the exact size of the case, and is placed at the bottom. One piece goes below the battery, and piece one goes above the battery. The one above the battery has a cutout for the chips on the backside of the calculator.

Very helpful. I misunderstood and thought one had to cut holes for each calculator key, something I thought might be tedious to do precisely. This looks very doable within about 10 minutes.

Thanks!

--Bob Prosperi
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02-08-2015, 06:49 PM
Post: #5
RE: DIY Case for NP-25
Yes, and maybe the need for the overlay is more clear now. I want something to cover the entire key area, and be contained within the adhesive pouch. You could interchange the overlay depending on which emulator you are running.

-- Sanjeev Visvanatha
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02-08-2015, 07:06 PM
Post: #6
RE: DIY Case for NP-25
(02-08-2015 06:49 PM)Sanjeev Visvanatha Wrote:  Yes, and maybe the need for the overlay is more clear now. I want something to cover the entire key area, and be contained within the adhesive pouch. You could interchange the overlay depending on which emulator you are running.

Indeed, this became clear as well (get it?) I just forgot to mention it. Also, another sleeve on the back to hold the other 2 personalities is clever. This solves the single biggest obstacle for this cool little toy+, how to recall keys for each personality mode.

--Bob Prosperi
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02-08-2015, 08:15 PM
Post: #7
RE: DIY Case for NP-25
(02-08-2015 06:36 PM)Sanjeev Visvanatha Wrote:  There are 3 cutouts in the case. One for the LED, one for the power switch, and one for the Program/Run button (only because a nearby component sticks up).

Dumb question: how do you actuate the individual calculator keys? TIA for enlightenment.

d:-?
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02-08-2015, 08:37 PM
Post: #8
RE: DIY Case for NP-25
(02-08-2015 08:15 PM)walter b Wrote:  Dumb question: how do you actuate the individual calculator keys? TIA for enlightenment.

It is not a dumb question. Enlightenment is as follows:

The PVC case is pretty compliant, so you can actuate the calculator keys very easily by pressing over top of them. You actually touch the case, but the key actuates just fine.

-- Sanjeev Visvanatha
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02-08-2015, 11:18 PM (This post was last modified: 03-30-2015 02:22 AM by Sanjeev Visvanatha.)
Post: #9
RE: DIY Case for NP-25
[Image: IMG_20150208_174334.jpg]

This is how I envision the overlay. This is a b+w photo of the 25C scaled and chopped up. With my rudimentary photoshop skills, I may be able to do this three times and in colour.

-- Sanjeev Visvanatha
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02-09-2015, 06:04 AM
Post: #10
RE: DIY Case for NP-25
Thankyou, Sanjeev. I'd expected some crosstalk to the neighbored keys.

d:-)
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02-09-2015, 06:11 AM
Post: #11
RE: DIY Case for NP-25
Hmmh. We need a 21, 25C, and 29C, don't we? I'll get my NP-25 soon so I can check dimensions ...

d:-)
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02-09-2015, 11:32 AM
Post: #12
RE: DIY Case for NP-25
(02-09-2015 06:04 AM)walter b Wrote:  Thankyou, Sanjeev. I'd expected some crosstalk to the neighbored keys.

None that I have noticed, but could happen depending on how thick of a foam base is used, I imagine.

-- Sanjeev Visvanatha
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02-09-2015, 11:35 AM
Post: #13
RE: DIY Case for NP-25
(02-09-2015 06:11 AM)walter b Wrote:  Hmmh. We need a 21, 25C, and 29C, don't we? I'll get my NP-25 soon so I can check dimensions ...

21, 25C, and 33C, from what I know.

-- Sanjeev Visvanatha
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02-09-2015, 03:18 PM
Post: #14
RE: DIY Case for NP-25
Sanjeev; Eric & Richard used photos that were printed on plastic "paper" for their DIY spice series calculator to do what you are doing. It holds up pretty well.
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02-09-2015, 05:25 PM
Post: #15
RE: DIY Case for NP-25
(02-08-2015 11:18 PM)Sanjeev Visvanatha Wrote:  This is how I envision the overlay. This is a b+w photo of the 25C scaled and chopped up. With my rudimentary photoshop skills, I may be able to do this three times and in colour.
Have you figured out any way to put a RED contrast enhancement filter over the LED area to make
the digits easier to see?
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02-09-2015, 10:16 PM (This post was last modified: 02-09-2015 10:21 PM by BobVA.)
Post: #16
RE: DIY Case for NP-25
(02-09-2015 05:25 PM)BarryMead Wrote:  
(02-08-2015 11:18 PM)Sanjeev Visvanatha Wrote:  This is how I envision the overlay. This is a b+w photo of the 25C scaled and chopped up. With my rudimentary photoshop skills, I may be able to do this three times and in colour.
Have you figured out any way to put a RED contrast enhancement filter over the LED area to make
the digits easier to see?

Here's what I did. Something similar might work.
Printing a filter on an overlay would be slicker, but the difference in height between the keyboard and the top of the display "bubbles" might pose a bit of a challenge with this case layout.
Bob
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02-09-2015, 11:48 PM
Post: #17
RE: DIY Case for NP-25
(02-09-2015 03:18 PM)Den Belillo (Martinez Ca.) Wrote:  Sanjeev; Eric & Richard used photos that were printed on plastic "paper" for their DIY spice series calculator to do what you are doing. It holds up pretty well.
I see. Is there a link you can share for this?

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02-09-2015, 11:55 PM
Post: #18
RE: DIY Case for NP-25
(02-09-2015 05:25 PM)BarryMead Wrote:  Have you figured out any way to put a RED contrast enhancement filter over the LED area to make
the digits easier to see?

I hadn't thought of a filter.

(02-09-2015 10:16 PM)BobVA Wrote:  Printing a filter on an overlay would be slicker, but the difference in height between the keyboard and the top of the display "bubbles" might pose a bit of a challenge with this case layout.

The overlay is switchable in my design. So, any filter would have to be static with respect to the case.

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02-10-2015, 12:33 AM (This post was last modified: 02-10-2015 12:35 AM by BarryMead.)
Post: #19
RE: DIY Case for NP-25
(02-09-2015 11:55 PM)Sanjeev Visvanatha Wrote:  
(02-09-2015 05:25 PM)BarryMead Wrote:  Have you figured out any way to put a RED contrast enhancement filter over the LED area to make
the digits easier to see?

I hadn't thought of a filter.

(02-09-2015 10:16 PM)BobVA Wrote:  Printing a filter on an overlay would be slicker, but the difference in height between the keyboard and the top of the display "bubbles" might pose a bit of a challenge with this case layout.

The overlay is switchable in my design. So, any filter would have to be static with respect to the case.
What about just putting a piece of red cellophane over the LED's? If you keep it separate from your overlay pocket then you could switch overlays without affecting your filter.
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02-10-2015, 06:26 AM (This post was last modified: 02-11-2015 02:30 AM by Den Belillo (Martinez Ca.).)
Post: #20
RE: DIY Case for NP-25
(02-09-2015 11:48 PM)Sanjeev Visvanatha Wrote:  
(02-09-2015 03:18 PM)Den Belillo (Martinez Ca.) Wrote:  Sanjeev; Eric & Richard used photos that were printed on plastic "paper" for their DIY spice series calculator to do what you are doing. It holds up pretty well.
I see. Is there a link you can share for this?
Sorry Sanjeev. No links since my hillbilly page died and i can't locate my DIY to take a picture. Troubling.

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