You're certain that there was no logo on the bottom of the switches? Do you know what keyboard this was and who had it? I presume no photos of it still exist, such as ones that might show a manufacturing date of the case or controller IC.
I don't even know that "true" "ICL switches" are even the Ericsson ones; it may be that they were the other type shown above with the Stackpole-like helical actuator spring. It's very hard to keep track of knowledge across forum topics; in fact, I tried to find a geekhack post earlier (one where I think you corrected me on Matsushita vs Matshita) that Google is adamant doesn't exist. Interestingly, though, having just checked right now, the forum search found it straight away.
Clicky: trailing arm provides a click, visible at the back of the slider; wide separator bar Linear: no trailing arm, and wide separator bar (per the white switches above) Tactile: no trailing arm, and narrow separator bar
The pictures on [wiki]NMB Hi-Tek[/wiki] should make this clear although that page still needs a lot of work. The definition of "eyes" plus examples would be well served by diagrams showing exactly what "eyes" are (2, 1, and 0) as it's not always clear.
Posted: 17 Feb 2015, 14:44
by vsev
Daniel Beardsmore wrote: A photo of the controller IC would be interesting — and any markings on the PCB. i.e. is it contemporary with the Loewe keyboard?
Here pics I just made, don't know if that's enough to date the board.. nothing like a date is in or out.
Stickers and PN
Spoiler:
sticker_type_X3305KNA.jpg (222.94 KiB) Viewed 2034 times
sticker_NCSerial.jpg (194.07 KiB) Viewed 2034 times
NC 8709 033 05001
SER.No 00000062
Controller
Spoiler:
controller.jpg (443.69 KiB) Viewed 2034 times
controller2.jpg (469.46 KiB) Viewed 2034 times
controller3.jpg (600.85 KiB) Viewed 2034 times
beside the big I the 2 numbers
D8748
L2478212S
INTEL 80
paper sticker on front pcb
Spoiler:
sticker_pcb.jpg (342.97 KiB) Viewed 2034 times
sticker_pcb2.jpg (390.87 KiB) Viewed 2034 times
marking back pcb
marking_backpcb.jpg (459.77 KiB) Viewed 2034 times
Desoldered one switch, one without diode cause others have one with.
There is no brand back the switch, nor front.
Spoiler:
switch.jpg (173.36 KiB) Viewed 2034 times
switch2.jpg (350.59 KiB) Viewed 2034 times
Posted: 17 Feb 2015, 19:55
by Daniel Beardsmore
D8748 is an Intel microcontroller, so that's not 1987. L2478212S, if taken to read week 12 of 1982, fits the same year as what's written on the smaller ICs.
So, it appears to be 1982, and contemporary with the Loewe keyboard (ca. 1984). Loewe sounds German (and the text on the Loewe keyboard is in German), and the Philips keyboard is made in Germany.
Both tie in well together. Sadly, neither one suggests a switch manufacturer.
Helps if you can read Swedish. Interestingly the patented version appears to have the diode under the stationary contact, and uses it as a terminal, making it inline with the circuit just as with RAFI RS 76 M. (Normally the diode is a wholly separate entity.)
The switch has a "time-delay mechanism", whatever that means.
Posted: 08 Oct 2017, 14:38
by mike52787
Daniel Beardsmore wrote: Finally, the patent for RMD 973 series:
Helps if you can read Swedish. Interestingly the patented version appears to have the diode under the stationary contact, and uses it as a terminal, making it inline with the circuit just as with RAFI RS 76 M. (Normally the diode is a wholly separate entity.)
The switch has a "time-delay mechanism", whatever that means.
posibly some early form of hardware debouncing? I cant think of what else that would possibly mean.
