geekhack Community > Reviews
Varmilo EC Switch
hasu:
# Varmilo EC Switch Review
**Disclosure:** Varmilo kindly offered me their new keyboard for review of their EC switch, I accepted it and got the keyboard for nothing. Thank you, Cynthia@Varmilo!
I'll try to be free from bias and flattery on this review as far as possible but it would be nice for you to know this.
The keyboard I got is MA109 JIS layout model with "Sakura Pink" EC switches. It seems that any keyboard with EC switch is not found in the market as of Jan 2018.
## EC Switch
This is Cherry MX style capacitive switch from Varmilo. There are three variants of key feel.
1) "Sakura Pink" linear 45gf
2) "Rose" tactile??(planned) linear 55gf
3) "Geeenery" click(planned)
They call this as "Ivy" switch now?
Varmilo's introductory video:
### External
The switch is Cherry MX compatible in terms of demension and designed for plate mount and has no fixing pins for PCB mount.
Notice that switch enclosure latch is different from Cherry MX and it doesn't seem to be possible to open the switch without desolder even using mounting plate with cutout designed for the purpose.
### Internal
EC switch doesn't make(close) contact electrically unlike other Cherry MX switches do. You can't replace Cherry MX(and its clones) with EC switche and vice versa, they are not compatible electrically each other.
EC switch is comprised of two metal plates and one of them is insulated with yellow-colored surface coating. Switch capacitance varies as those contacts get closer or further along switch stroke.
While Cherry MX has crossbar contacts on its plates, which look like pic below shows.
https://deskthority.net/wiki/Gold_crosspoint
### Cherry MX capacitive mod :)
This pic shows brown Cherry MX and sakura pink Varmilo EC switch side by side.
As you can see, EC switch construction is almost the same as Cherry MX and you may think Cherry MX can be turned into capacitive swtich somehow. It should work, right? Let's try it now.
You have to file off crossbars on contact plates and insulate, that is it, pretty easy huh? :D I used Kapton tape as insulator here.
The result? Yes, the mod swicth works in Varmilo keyboard! but acutuation point is not optimal clearly, with Brown tactile slider at least. With Red linear slider it is apparently proper, though.
### Key Scan and Capsitance sensing
The Varmilo keyboard uses chip LC17C6701 for sensing, manufacturer is unknown. The chip has 10 sense pins and 14 drive pins, and key switches are aligned on 10x14 matrix.
The chip can sense 10 lines in parallel per a pulse on drive line. The pulse width is around 2us(yellow: drive, blue: sense).
When key is released:
When key is pressed:
And this video shows how sense line changes during a key is typed.
https://i.imgur.com/ev9WrGO.gifv
This pic shows pulse on adjacent three drive lines and you can see that sensing 10 keys on a drive line takes around 5us in total. So it takes only about 70us(5*14) to scan all keys on the 10x14 matrix.
Scan rate is pretty fast in comparison with classic Topre chip TP1684/3 which takes usually around 15ms to its key switch matrix. See this for the detail: https://imgur.com/a/jat2a
It seems capacitance change on EC switche is not so linear throughout key stroke, it doesn't change much especially at bottom of stroke.
### Microcontroller
It is marked as LC17C6801 on SSOP24 package and uses Holtek product ID(04d9) on USB but no info is found in their site. The chip communicates with sensor chip via three I/O lines.
### Power consumption
The keyboard consumes 105mA when its backlite turns on while 22mA when it turns off.
For reference, the below shows how much current my keyboards draw.
- Realforce 101(PS/2) consumes around 11mA.
- IBM 62-key 4704(6019284) and IBM 122-key terminal(6110345) consumes around 160mA.
- HHKB Pro1 consumes around 42mA.
- HHKB Pro2 consumes around 140mA.
- HHKB Pro JP consumes around 37mA.
### Resources
unsorted pics: https://imgur.com/a/sYv7O
## Keyboard Info
The keyboard I got is JIS layout model with "Sakura Pink" EC switches called as MA109CO2W/LLK2V on its package.
MoreI'm not the right person to review keyboard and won't go further on this topic.
The followings are something interesing I found:
- wood grain texture on plastic case; (I'd say this is rediculous :D but yeah it is all about preference)
- effective rubber feet. better than my HHKB at least
- sturdy case frame
- keys are less wobble and less rattle(including stablized keys)
- stabs are lubed with good mount of grease; not sure if it is good practice of lube but it works
- mini USB detachable. I know some people dislike mini port.
### How to take apart
No hidden screw on bottom, no need to peel any rubber feet and label plate fortunately.
1. two screws on top of plate, to bolt board down to bottom case, you have to get some keycaps off to find the two screws around "F" and "Enter" key.
2. clack open case with phone opener or thin plastic plate like guiter pick
3. unscrew four screws on bottom of pcb to unfix it from upper case
suicidal_orange:
Thanks Hasu for an interesting technical review, I doubt many reviewers will get out the oscilloscope or measure the power draw :))
Findecanor:
On the outside the switch looks very much like a Kailh switch.
Mine does not have the inner lip on the bottom housing but I think there might be other Kailh switches that do.
Rob27shred:
Thanks for the review! These switches are pretty interesting, although the tactile & clicky variants are of more interest to me. I wonder how Varmilo will over come the actuation point issues you ran into with the modded MX brown. I mean I get it was quick & dirty mod just to see if it would work, but I bet that issue carries over to their design as well since using a MX red stem fixed it.
MajorKoos:
Thanks Hasu. That's an awesome review.
I dig how you made your own version of the switch for testing - uber cool.
Navigation
[0] Message Index
[#] Next page
Go to full version