how do none magnetic switches work?

[digibloke]

I'm showing my ignorance here but How the heck do simple push button switches on 70's leds work? I can see how reed switches work as it's easy to see where they're connected to (one wire in, one wire out) but when I look at a hughes or nat-semiconductor or frontier module it looks like pressing the button or setting switch just presses a folded piece of metal inside of the module which then makes contact with itself??? I have a feeling that it has something to do with the the extra contact metal piece inside all of these modules (always facing the opposite way to the others and minus a button) but just can't fathom it out - it doesn't seem to be connected to the setting or time/date switches?

Is there anywhere on the net that explains how they work or can anyone here PLEASE enlighten me.

[digibloke]

Just been looking at a Frontier module (looks identical to the "John doe" module in Azimuths Omega except it's white)...

http://digital.superman.ws/phpBB2/viewt ... c&start=10

And the third metal contact touches the side of the + down battery.

I still dont get it though

[Lordpulsar]

If you take a frontier or (non-reed module).. Insert the batteries and short the (usually negative) end of the battery to the metal contact on the module where the button touches it should light !... Hey presto !!!

[retroleds]

Digibloke - the contacts are, well, contacts...they merely complete a circuit which generally uses 1.5 volts for switching purposes, ran through the case, back to the buttons. The 3 volt combination(2 batteries) is to run the display. There are a few exceptions, notably: Litronix, calculator watchs of almost any make, and any "touch command" type watch. Running 3 volts through the switching circuit is unneccesary and dangerous to the health of said module. So glad my late father slapped the difference between parrallel and series circuits through my head!

[retroleds]

Digibloke: Those extra,non buttoned contact are of no concern of yours. Generally, they are just there for extra securing of the module boards to the outer(or inner) module ring - you know, piece that keeps your batteries seperated. Think about it: you have two batteries, but the case is grounded to the center tap(the point where the batteries meet). There is only 1.5 volts going through the case, to the buttons. I'll be happy to take pictures with the VOM hooked up to a lit module, if anyone seriously wants to debate this point. ALWAYS test switching functions from the center tap of your battery stack(with the noted exceptions of "touch command" and "Litronix" or other makes that use two batteries facing same way.....the electrical pathway is on those is for the "Advanced class"). Never fear asking a "dumb question" on a forum...you weren't built in a watch factory, and not everybody has the same experience with "Arcs & sparks".

[digibloke]

Thanks very much for the replies. Does that mean that when you press the button, the pressure causes the contact to move upwards and make contact with the case back?

Doh! - It never even crossed my mind that the case back was involved in the circuit. Don't know how I could have missed this given the amount of times I've refitted battery retainer springs onto Pulsar casebacks.

It's always good to go from "hey it works" to "how the heck does it work" though eh?

[retroleds]

Digi: Case back and body carry current over to button, button gets pushed in and contacts the contact on the module. At that point the circuit is completed for the particular section of switch circuit(time, day,date, etc.)
For most modules the lightest contact that makes electrical contact is all that is necessary. The bent over contact was just a way to make the contact metal stronger and to give it a little flex, in case some desperate "digi-bloke"(just couldn't resist) decides that pushing harder might be the cure. Cleaning the contacts thoroughly is the answer...but we'll save that for another missive.