Ideas for really small slide switches?

Perhaps by going further and look for a way to include both the light and the switch into a tiny push-button toggle, where appropriate? Something like was used on the HP-2116, for example? Wow, that is small space.

Hmm... In the act of "pushing" the switches would it be acceptable to consider finding a way of sensing if an LED is touched or pressed and using the LED itself as sensor as well as display?

But I'm no help on tiny switches. Best of luck!

Jon

Look at

It will occupy around 15% of your surface availble (one side only) for

50 switches

Zara

"larwe" schrieb im Newsbeitrag news: snipped-for-privacy@g49g2000cwa.googlegroups.com...

The 0,050" switches are availlable with j-leads from

this saves a lot of space.

MIKE

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Michael Randelzhofer
FPGA und CPLD Mini Module
Klein aber oho !

Off the wall suggestion - forget mounting switches and use test pads arranged as switches in SPDT configuration and a small metal stylus to short to 1 or 0. I do assume you will have a switchscanner in there in some form of other. This means building up switch patterns and remembering each switch until an 'action' switch is operated.

Might save a lot of space.

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Paul Carpenter          | paul@pcserviceselectronics.co.uk
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That's very much on my wall, I was going to suggest something just one step above that. Stack together on an axis a few metallic plates with a profile resembling a switch, and use two pcb's to create a sensor pad on both sides. Something along like this - (sorry for the poor ASCII art):

/-----\ + + /-----\ | + + | | | | | | | | | | | | | | | | | | | | | + | | \ x + + + xx / \ | xxx + + | xx | (rotation | | x rubber band to keep | * | + switches centered | axis) | / + + / \ / + \ / | \ / | | || | 1-| || | | |

Well you did say theoretically operable, a bit like the old calculator watches of 70's/80's era.

And how often how easily a scope earth clip pings off and does it for you but on the _wrong_ 0603 :-^

Well it is an alternative.

Just seen them, PDP-1 was before my computing time I worked on 8's, 11's micro-11's (various) and VAXes various.

...

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Use minature SMD phototransistors, and the slider blocks the ambient light? Adds problems with finger placement during operation, but definitely small and low on the moving-parts count. I guess an equally viable solution would be side-looking SMD IR LED and detector pairs.

Though I'm having no luck finding IR side-looking LEDs, and non-IR side-looking phototransistors. You might do better.

You don't need 2 contacts. . Use a single pad plus the user's body resistance to the part of the board that they are holding it by.

I'm not sure I understand this. You're proposing contact plates on one layer of the PCB, and this structure held into a routed hole in a second layer of PCB material on top of it?

Very nifty site, although I don't care for the proprietary software. Bookmarked!

• or - (Was in a hurry) I thought the "switch assembly" could stand alone, above the PCB, but your "routed hole on a second pcb" will definitely make it look better.

I thought two small pcb strips (not in my drawing) held vertically on both sides along the bottom of the "switches" would provide the contacts. Small metal brackets soldered to an horizontal PCB (if we think of the switches as vertical) could do the same.

Sorry if this is not clear, I'll make a drawing when I get some time on a system with a CAD or ray-tracing program.

( It will take a while, this week I am undergoing training on how to use an unnecessarily complicated 3rd party communication library in one of our products. The kind that takes 3000+ lines to write a basic "Hello world" program... )

Roberto Waltman

[ Please reply to the group, ] [ return address is invalid. ]

Please don't take this much trouble on the matter - I am currently looking at the Alps SKRK series 2.9mm x 3.9mm switches which might just fit the application.

I know the feeling only too well, and commiserate.

How about an unplated through-hole with half of the hole one contact, the other half another contact?

Huh, hard to describe.

If you have a regular plated through hole on a PCB, then poking a meter probe at the hole for a voltage measurement (for instance) results in the tip of the lead centering itself in the hole. A stylus of the right shape would do the same thing.

Now if half of that hole were one node and the other half another node, then the metal stylus would make contact between the two nodes and complete a circuit. The tendency for the stylus to center itself would help assure contact.

The hole would have a half ring ( 170 degrees of a circle ) on one side and would be insulated from the half ring on the other. The stylus contact makes the connection. 0$ spent on switches.

Spehro's suggestion is closest, so far, to what I had in mind.

shows a front panel layout that is ALMOST final. The eight control switches are giving me trouble.

By the way, someone pointed out to me today that a KIM-1 emulator would be another cool and easy thing to do on a similar hardware platform. There are some very nice little surface-mount 7-segment LEDs, I am giving it serious consideration. I won't have to modify substantially the "RTOS" (really a strong word for it) I developed to run the PDP-1 emulator.

Oh, one other thing: A citizen suggested yet another method, which is a magnetic stylus and SOT23 Hall effect sensors as the "buttons". I rather like this :)

"larwe" a écrit dans le message de news: snipped-for-privacy@g49g2000cwa.googlegroups.com...

Or reed switches?

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Thanks,
Fred.

I never saw one as small as a SOT23 Hall effect sensor.

larwe wrote:

Strange, I still can't find it. Oh well.

The smallest toggle switches I've seen are the ITT Cannon GT series Sealed Ultraminiature Toggle Switches:

Some of thsoe are only 4.06 mm wide, so you could cram a row of 18 of them onto an 86 mm wide card with a little room to spare.

Note that having the various indicator rows not line up with the switches will make it relatively unpleasant to operate.

I've got it! :-) Make it out of flex circuit, so that it unfolds to double size, to reveal the state indicators, sense switches, etc.

That sounds clever.

Now, am I missing something here: how about a DIP switch bank? As once used on ISA cards to set IRQs etc. Quite practical to operate with a miniature screwdriver, cocktail stick, etc.

NT