[Interest Check] FK-5001/9000 calculator replacement

[Engicoder]

Background
Some time ago, I developed a replacement for the stock, failure prone calculator module in the Focus FK-9000. This project was essentially a "two" off that I made for myself and Chyros. You can see the module on Chyros' youtube channel in his "Project F" at around the 10:30 mark. In the time since the video was posted several people contacted me expressing interest. I am finally looking at do a small run of these for those who are interested.

Details
The replacement will be a plug in replacement for the stock module and include a OLED monochrome graphic display. (Some minor modification of the the upper case is require for the display to fit). The module functionality will include:
* Identical functionality to stock calculator including memory
* Selectable RPN input mode
* Persistent clock with date
* Multiple configurable settings for clock format and style
* Eliminates need for stock battery
* Compatible with FK-5001 and FK-9000 that use the single KB/CAL key

Questions for those interested
1. Offline availability: The prototype included a rechargeable Li-on battery in order to support using the calculator when the keyboard is not plugged in and/or the pc is not turned on. For packaging simplicity and cost savings, I am thinking about removing the offline capability and using a simple coin cell to retain clock/date information.
Question: Do you consider offline availability essential even at higher cost/complexity?
Update 12/6/19: Moving forward without offline availability

2. Case modification The display used on the prototype requires that the plastic ridge that locates the stock display be removed. This modification is simple to perform and does not change external appearance. I have made some inquiries in hopes of finding a display that would not require any modifications and would have a higher resolution.
Question: Does having to modify the case turn you off from this solution? Would you be willing to pay more (~$20) for a display that does not require case modifications and has higher resolution?
Update 12/6/19: Ordered display sample that may not require case modification. Will confirm once the display arrives.

3. Older FK-5001 and FK-8000 support: Older FK-5001 models used separate KB and CAL buttons to switch modes and the FK-8000 has a different mounting method and pin header. The module does not currently support these keyboards. If you have one of these keyboards and are interested, let me know. I will investigate adding support.

Pricing
I do not have final pricing yet. Pricing is on the conservative side to avoid surprises. Depending on final configuration, I estimate the cost to be:
Base module ~ $50-60
Offline availability ~ +$15
No mod display ~ +$20

If you are interested please respond or send me a PM with the answers to the questions. Also let me know what you think about pricing.

[parkerlreed]

Thanks a ton for the post!

1. My 5001 variant 2 has a coin cell for battery that I tend to leave out anyways. So I'm not terribly concerned about having offline availability as I don't use it to start with.

2. As long as it doesn't affect using the stock display later on (mine still works), I wouldn't mind either way. Case has already been apart and one of the snap gone, so I'm not too worried about keeping it unmodified.

3. My 5001 has the single KB/CAL so no worries from me there.

So yeah definitely count me interested!

[just_add_coffee]

AWESOME!
1. I kinda do like the offline availability, but it's not a dealbreaker.

2. Whichever you deem as looking the best. I'm willing to pay more for a high-resolution display and/or modifying the case.

3. Whatever you decide. I'm mostly interested in the 5001 and 9000 models.

Can't wait!

[XMIT]

I'm so glad to see that this is moving forward!

1. I'm cheap and a simple coin cell works well enough.
2. I have no qualms about modifying my case.
3. I have all of FK-5001, FK-8000 and FK-9000 available, in various states. Support would be welcomed if it did not add cost.

Pricing is what it is: appropriate for a tiny run or a few one offs.

[wadeak78]

I don't need offline support, and I'm fine with nodding my case.

[adamcobabe]

No offline, not a deal breaker.
Would pay more to avoid modding the case.
I only own the newer fk-5001 and an fk-9000.

[headphone_jack]

Offline doesn't matter that much to me, so whatever works best for you.
Same with the case mod, it would be nice not to but i don't care either way.
I use one of the older 5001 variants with the separate toggle buttons, having support for that is a must for me to buy it.

[jessesevorg]

I own a newer FK5001 and would love this!

[Engicoder]

A quick status update:

From the responses, I plan to move forward without offline availability to simplify both design and installation. I have located a display that I think may work without modifying the case and have ordered a few samples. I will update this thread after they arrive and I test them.

[listofoptions]

count me in! waht kind of unit cost are we looking at?

[ZedTheMan]

Gotta admit, I'm really considering getting an FK5001 I found on ebay alongside one of these, but that's really a project for once I sell a lot of stuff in my upcoming winter sale.

[Engicoder]

Time for a long overdue update. Take a look and please share any questions, concerns or feedback you have.

"No mod" display
I received the display that is a candidate for use with out modification of the case. The good news is that with a bit of light sanding, the display does fit in the existing opening in the case. The bad news is that due to the display area not being centered on the the display glass, there will be a portion of the opening that cannot be used. Here is a picture of the display in the case

no-mod-display.jpg (120.97 KiB) Viewed 986 times

Note: I added the red line to indicate the edge of the active display area, it does not appear on the display. The silver portion could be covered/ colored so that it is not as conspicuous.
To summarize, the pros and cons of the "no-mod" display are:
Pros:

• No modification of case required
• Higher resolution (256x64 vs 128x32)
• No depth gap between case and display

Cons:

• Does not utilize entire display area, as seen in picture above.
• Slightly higher cost ~$2 per unit

What are your thoughts on this display?


Interface Board
This project uses two pcbs, one to interface the keyboard and the other to perform the calculator/clock functions and drive the display. The two boards are connected by a 5 wire cable over which keystroke and status information are exchanged. I completed the pcb for the interface board. Here is a pic of the board mocked up in an FK-9000.

interface_board.jpg (180.25 KiB) Viewed 986 times

I will be building this board this week and testing the software.

Please share any questions, concerns or feedback you have.

Ben

[parkerlreed]

Thanks for the update!

I feel like the offset display would bug me, although with a color matched piece of plastic or the like, that could be severely reduced. The extra resolution of the no mod I feel like wouldn't come in as useful since it appears there no PC interface? Static logo/time/calculator I would assume would look fine either way.

Originally I was indifferent to case modding, so I think I would be fine either way. Is the sanding that is mentioned still applied towards the case?

PCB looks fine. Whatever works for you there

So I think in the end, I'm still leaning towards the case mod display. Looks nicer overall with minimal tradeoff.

[XMIT]

The display in Chyros's video looks good to me. The off center display would be unfortunate.

Higher resolution would make it even harder to read the text in the menus, unless you selected a larger font, in which case there is no point.

[Engicoder]

I feel like the offset display would bug me, although with a color matched piece of plastic or the like, that could be severely reduced. The extra resolution of the no mod I feel like wouldn't come in as useful since it appears there no PC interface? Static logo/time/calculator I would assume would look fine either way.

The display in Chyros's video looks good to me. The off center display would be unfortunate.
Higher resolution would make it even harder to read the text in the menus, unless you selected a larger font, in which case there is no point.

The increased resolution would be used for better clarity of the text, the size would remain the same.
At this point I am leaning towards the original display as it does the job, is cheaper, and for me requires less work

[adamcobabe]

The edge showing on the side would really bother me. I want it to look good from the outside even if that mean I have to mod the case inside. Thanks for the effort either way.

[ZedTheMan]

Hey, do we have an update? I may have a 5001 old style coming in, are there any possible mods that can be done to make this work?

[dcopellino]

Hi Engicoder, I found your post very interesting as new focus fk 5001 owner. To say it all, I am still waiting mine to be delivered, since I bought it on eBay from a USA fellow who declares in his listing that "A new battery was installed and the LCD calculator tested fine; see photos for details. Note: The battery shipping tab will need to be removed before the LCD calculator will function." Being said that, I am aware of shipping troubles may occur and focus electronics is not so much reliable. So, consider my interest in your project even though the incoming keyboard belongs to early models, being a 5001 variant A. Anyway, I'd like to involve you on another project to which I am fond of and I am sure it's within your reach. If you have time and will, I'd like to have your opinion about this fantasy of mine... Transforming an old IBM M3 numpad in a standalone calculator. Major details here viewtopic.php?f=2&t=23408&p=459537&hili ... lc#p459537

[headphone_jack]

Any updates? Hoping to get my hands on a module before the borders close!

[RiverDax]

I am interested in this!