deskthority

Which function does the two additional pins possess? Are the switches 2-pole so I can complete two circuits? Most importantly, however, do I have to use all four pins?

That depends on the matrix. Many official Cherry boards (such as late G80 series) utilize the extra 2 pins (metal wire) to make bridges or some jumping in the matrix. On older generation G80 boards, they are most of the time not used besides in three or four keys, where they do some matrix bridging.

You can basically check if there are any traces surrounding the extra pins on your PCB. If so, you have to resolder them, if not you can ignore them (or abuse them for your own circuit to give power to LEDs.. or something like that). On older keyboards with n-key rollover, the extra pins are used for diode switching, so of course they are required.

Cherry offers their switches in four variants:
2 pins - no extras
2 pins + 2 with metal wire bridge
2 pins +2 with led
2 pins +2 with zener diode

I hope this helps. If you need any more help, ask along.

Thanks! It's the clear cherries I bought from you, so no pcb yet.

I haven't opened the switches yet, but it looks like the pins are just a bridge wire like you said. The difference between these and the 2-pin variant is that the bridge is there by default?

Minskleip wrote:Thanks! It's the clear cherries I bought from you, so no pcb yet.

I haven't opened the switches yet, but it looks like the pins are just a bridge wire like you said. The difference between these and the 2-pin variant is that the bridge is there by default?

Yep. By now most OEMs order the bridge variant, even if the bridge is useless in their circuit, simply because it provides a tiny bit of extra stability and because they are cheaper in mass order (because everyone buys them and the production run is higher, I guess). If you do not need them in your circuit you can either bent them off or remove the wire by opening the switch.

This is just what I needed, thank you. Now I can use the specs from Cherry's site and start designing the PCB.

I'll make a thread tomorrow for the project and add some layout suggestions for discussion.

Minskleip wrote:This is just what I needed, thank you. Now I can use the specs from Cherry's site and start designing the PCB.

I'll make a thread tomorrow for the project and add some layout suggestions for discussion.

Cool, looking forward to it! Somewhere on my home computer, I have a catalog of all Cherry parts in various CAD formats for PCB design. That might help you a lot to get started. I'll check when I go home in a while and report back tomorrow.

sixty wrote:

Minskleip wrote:This is just what I needed, thank you. Now I can use the specs from Cherry's site and start designing the PCB.

I'll make a thread tomorrow for the project and add some layout suggestions for discussion.

Cool, looking forward to it! Somewhere on my home computer, I have a catalog of all Cherry parts in various CAD formats for PCB design. That might help you a lot to get started. I'll check when I go home in a while and report back tomorrow.

That'd be swell! Do you know of any decent PCB design software?

Most use this I think:
http://www.lis.inpg.fr/realise_au_lis/kicad/

Thanks, I'll check it out!

sixty wrote:Cool, looking forward to it! Somewhere on my home computer, I have a catalog of all Cherry parts in various CAD formats for PCB design. That might help you a lot to get started. I'll check when I go home in a while and report back tomorrow.

I would love to have these files. I'll pm you my email address right away if you'd prefer to send them that way.

PrinsValium wrote:

sixty wrote:Cool, looking forward to it! Somewhere on my home computer, I have a catalog of all Cherry parts in various CAD formats for PCB design. That might help you a lot to get started. I'll check when I go home in a while and report back tomorrow.

I would love to have these files. I'll pm you my email address right away if you'd prefer to send them that way.

I emailed you!

sixty wrote:I emailed you!

Thanks, I have been playing around with Eagle a little but the free version is not very capable, and their other versions are, well, not supposed to be free. Next I will have a go at KiCAD, it looks promising and it is free =)