Leopold LC660C internal Bluetooth mod

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16 Jul 2018, 20:18

I added a Handheld Scientific BT-100 module to my Leopold LC660C and it fits and works!

I also put up a video on the exploration of whether or not this was possible, but it doesn't really cover the detail of the actual conversion:

Below is mostly a reproduction of the imgur album here https://imgur.com/dt9im6I with some additional notes added.

Because the module didn't work with keyboards that register as a keyboard and a mouse, I couldn't really use the module. Later, I wound up with this Topre board, and it identifies as a single device, so I wanted to see if this mod was possible


I need to desolder some of these taller items, but the rest should fit.


Lowest profile I can get after removing the USB, PS2, battery connector, and speaker, and it fits!

This layout means I can maintain the current button and USB charging port. Which is great, because I didn't want to have to move those.


Hot glue is mother's milk to makers. It holds everything in place. I've connected the on board USB mini connector to the former USB connector on the Bluetooth module using magnet wire.

There was some cutting involved on the supports to get everything to fit, but this thing is so overbuilt and so well fitted together it could probably lose half of its supports and be just as solid.

I was pretty worried the magnet wire wouldn't be enough to run USB's high frequency stuff, OR the whole thing would interfere with the Electrostatic capacitive switch sensing, OR the plate would kill the antenna range to uselessness. But all those concerns were unfounded!


So far I've only drilled ONE hole in the outer case...

There are two LEDs, and a charging port that I need to figure out how to expose those in a way that maintains this Leopold appearance. Still, it has a speaker that beeps in useful patterns so I can operate it without the LEDs for the most part.


I really couldn't believe it actually worked. I mean, technically it should have worked, but it was such a risky mod for such a nice and expensive board.


And it still runs wired!

This is a fun and risky little project that has brought back the usefulness of this board, and makes use of a bluetooth adapter that wouldn't work with my normal keyboards. I had one thing I wasn't using, and one thing I wanted to use more, and now I have something greater than the sum of its parts! :D

Remaining concerns and questions for the brilliant Deskthority minds:
1. Is enameled wire (motor/magnet wire) sufficient for this kind of USB connection?
2. I still need to make available the charging port for the BT module. What's the best way to cut a square hole that doesn't look horrific?
3. Should I expect any issues with the EC sensing in the future? There's a battery and a BT module down there now, pretty close to the board. I haven't really given it a prolonged test period yet.
4. Any ideas on where to put the status LEDs so they're very visible, and how to make them visible on the case without destroying the slick aesthetic of this Leopold design. (Some kind of smoked window install?
5. Any other sundry warnings or threats of violence for drilling holes in a lovely bit of kit. :lol:

User avatar

17 Jul 2018, 09:41

Cool! Having installed Hasu’s Bluetooth upgrade in my HHKB, I know exactly where you’re coming from. Only I didn’t have to undertake the work! The HHKB’s extra holes (some good at last from its USB hub) made this an easier task indeed. You and your Leopold have your work cut out…

Once you do have it working, this is a spectacular upgrade. I use my HHKB more than ever, as it’s now a champ on my iPad too where it wouldn’t even connect before (that wretched built in hub was too power hungry). With a decent sized battery (I had a 2500 mAh sitting spare) it runs for days and days of heavy work, and I’m yet to run it low let alone out of juice. You’re on the right track to a killer keyboard in practical use.

Now, as for charging: Hasu handled that by doing double duty on the mini USB port. It takes power for the battery charger as well as the keyboard. Plug the board into a USB socket, and it’s always charging (until full, as indicated by an LED). The power switch toggles between USB and Bluetooth operation. Perhaps you could take a similar approach?

Charging and especially Bluetooth connection LEDs are nice to have. They make the keyboard’s state obvious at a glance. I’d consider them secondary features, however. What is essential is a convenient means to charge the battery! Get that working and you’re at the races.

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20 Jul 2018, 14:32

I think I've finalized the build. I expanded the hole for the button, and cut a square hole for the charging port.

For now, I'm skipping the LEDs, as the BT module actually uses the keyboard's LEDs to indicate charging state! Further, the speaker tones are very descriptive of the BT module's actions, states, and any complaints.

So, I've taped down the magnet wire, added glue reinforcing the parts, and I'm gonna run it until it until something breaks!

It is SUPER handy! Plus the build quality on this board is so tight, I feel really good carrying it around, and sometimes, tossing it around. Very happy with this build :D

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