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geekhack Community => Keyboards => Topic started by: 1391406 on Tue, 21 May 2013, 02:24:21

Title: ID this switch?
Post by: 1391406 on Tue, 21 May 2013, 02:24:21
From a 1989 Pravetz keyboard. Anyone know what it is?

(http://i.ebayimg.com/t/MECHANICAL-PRAVETZ-AT-XT-BULGARIAN-KEYBOARD-1989-PERFECT-WORKING-CONDITION-/00/s/MTIwMFgxNjAw/z/pTIAAMXQ8ABRkVkN/$(KGrHqJ,!lwFFy5pmCo9BRkVkN(,g!~~60_57.JPG)

(http://i.ebayimg.com/t/MECHANICAL-PRAVETZ-AT-XT-BULGARIAN-KEYBOARD-1989-PERFECT-WORKING-CONDITION-/00/s/MTIwMFgxNjAw/z/HEoAAMXQkcZRkVkS/$T2eC16F,!yME9s5qE+fgBRkVkSUdQ!~~60_57.JPG)
Title: Re: ID this switch?
Post by: nubbinator on Tue, 21 May 2013, 02:53:18
I'm assuming you're looking at this keyboard on eBay (http://www.ebay.com/itm/MECHANICAL-PRAVETZ-AT-XT-BULGARIAN-KEYBOARD-1989-PERFECT-WORKING-CONDITION-/171040337074?pt=PCA_Mice_Trackballs&hash=item27d2cc6cb2), correct?  It's this keyboard (http://www.pravetz.info/pravetz-16es.html) (another link (http://www.old-computers.com/museum/computer.asp?st=1&c=615)).  The PCB shots on the eBay page are more helpful to me.  If it is mechanical, it's got to be some permutation of a buckling spring or spring over rubber dome keyboard (Ripster lays out a few here (http://imgur.com/a/VrFtD)) given the back side of the PCB. 

I'd love someone to chime in and say I'm wrong that it's Hall-Effect or some other uncommon switch.
Title: Re: ID this switch?
Post by: 1391406 on Tue, 21 May 2013, 03:04:06
Quote from: nubbinator on Tue, 21 May 2013, 02:53:18
I'm assuming you're looking at this keyboard on eBay (http://www.ebay.com/itm/MECHANICAL-PRAVETZ-AT-XT-BULGARIAN-KEYBOARD-1989-PERFECT-WORKING-CONDITION-/171040337074?pt=PCA_Mice_Trackballs&hash=item27d2cc6cb2), correct?

That's the one.

Title: Re: ID this switch?
Post by: BlueBär on Tue, 21 May 2013, 07:25:53
Quote from: nubbinator on Tue, 21 May 2013, 02:53:18
The PCB shots on the eBay page are more helpful to me.  If it is mechanical, it's got to be some permutation of a buckling spring or spring over rubber dome keyboard.

As you can see from the pictures there defintely is a rubber dome, I guess the spring is under that white slider. Never seen that switch though.
Title: Re: ID this switch?
Post by: terran5992 on Tue, 21 May 2013, 09:34:34
Looking at the stem ,I'm guessing its made by cherry.
Title: Re: ID this switch?
Post by: fohat.digs on Tue, 21 May 2013, 09:59:49
I have bought several plunger-over-dome keyboards that were MX compatible but not Cherry (including Packard Bell and Gateway).

Look at how rounded the tips of the cruciform are - usually they are hard and square.
Title: Re: ID this switch?
Post by: BlueBär on Wed, 22 May 2013, 04:30:00
Quote from: terran5992 on Tue, 21 May 2013, 09:34:34
Looking at the stem ,I'm guessing its made by cherry.
No, in fact, most mechanical switches have these cross-style stems. There is no indication that this switch was made by cherry. Also I don't think cherry every made a spring and dome switch.
Title: Re: ID this switch?
Post by: Findecanor on Wed, 22 May 2013, 09:52:44
From what I can see through the semi-transparent PCB, it looks like it uses some kind of conductive pad on the bottom of each slider. Whether is has conductive rubber or foam and foil, I can't tell.