But then we're on a road far away from KISS!
And a solid state logic solution would look good.

That would be my suggestion, even a simple microcontroller.

 

Yea that's what I'm thinking at this point as well. But again this is Rev one, so I think the lockout will have to come in Rev 2 or 3 and them integrate the microcontroller or something that allows checking of the button state and the ability to lock out the fire current in the event of a malfuction.

For now I want to keep it simple so I think what inwo provided perfectly fits that bill. Thanks to everyone that supplied input and helped.

 

The supplier in your link has switches with N.O./N.C. and leds.

PM251/PM221

Even with another design, the N.C. for testing switch position/function seems best.

 

If your mom button contacts are intended to switch the e-match current they should be rated for at least 1A DC. What is their rating? If less than 1A then you will need a relay or power transistor, controlled by the button, to fire the e-match.

 

The supplier in your link has switches with N.O./N.C. and leds.

PM251/PM221

Even with another design, the N.C. for testing switch position/function seems best.

Yes now that I understand a little more what I'm looking at/for I do see they offer some bigger buttons with NO/NC and even some tri-color LED ones (ooo the posibilities )

I'm still not 100% clear though on how I would use the NO/NC to lock out the fire mode because pushing the button would seem to do the same thing.

If your mom button contacts are intended to switch the e-match current they should be rated for at least 1A DC. What is their rating? If less than 1A then you will need a relay or power transistor, controlled by the button, to fire the e-match.

They are rated 2A 36VDC

 

Sorry for cat scratching, I'm not in the mood to do anything serious today.

Idea is to use a control relay (CR1/arm) in lieu of the multi-pole key switch.
The contacts would swap polarity as in first diagram.

The relay pulls in with a SPST key switch, but only if all fire buttons are normal.

Once armed relay remains latched thru holding contact of CR1 until reset by moving key switch to off.

 

Your catch scratch is perfectly fine. I think I understand. Looking at the 1NO1NC buttons they have they are a little bigger 22mm vs the 16mm I got. I've emailed them to see if I can get the 1NO1NC in the 16mm like what I have. The 3 color ones they have seem easier because they are 1 common and 1 contact for each color which then eliminated the need to reverse the polarity.

 

The arm section should be valid for any configuration of "fire" circuit.

Should be pretty fool proof even if something is sitting on a switch.

Most switches used forced contacts, by which N.O. cannot "make" or stick without N.C. being open.

Now if this was an industrial safety circuit, it would require two sets of N.C. contacts and a special self checking safety relay, to make sure the user hasn't disabled something.

 

So the company that sent me the first button got back to me with this button.

http://www.aliexpress.com/store/pro...M162H-11E-R-12V-S-IP67/737142_1955882070.html

It can be 1NO1NC or they can make it 2NO2NC and stay in the 16mm size I like with the red and green LED option.

 

Go with the 2 of each.

There are different switch forms.

If you want a safety N.C. set that is isolated from the fire circuit, you need 2, of the form in the link. Like sw 1.

There is still a (slim) chance of a failure where a N.O. switch is stuck on and N.C. is not open..

See if they make a sw2 type. IMO

Looks like this is one, but 25mm.
http://www.aliexpress.com/store/pro...ch-PM251F-11E-B-2-8V-S/737142_1346384432.html

See the double break? 4sw terminals!
Might as well ask them again.

 

Go with the 2 of each.

There are different switch forms.

If you want a safety N.C. set that is isolated from the fire circuit, you need 2, of the form in the link. Like sw 1.

There is still a (slim) chance of a failure where a N.O. switch is stuck on and N.C. is not open..

See if they make a sw2 type. IMO

Looks like this is one, but 25mm.
http://www.aliexpress.com/store/pro...ch-PM251F-11E-B-2-8V-S/737142_1346384432.html

See the double break? 4sw terminals!
Might as well ask them again.

I think the 2NO2NC is the most they can do on the 16mm button because of the size which is why you found the 4NO4NC in the 25mm button

 

I am understanding correctly that when you say sw1, sw2, 4sw you mean 1NO1NC, 2NO2NC and 4NO4NC right?

 

The most you should need is one N.O. and one N.C..

The issue is that often a circuit will require separate contacts. ie. No common!

Need access to all 4 terminals if you use circuit similar to my suggestion.

The 25mm showed this 4 terminal, single N.O./N.C. arraignment. This is the ideal contact form for safety switch.

The "2NO2NC is the most they can do on the 16mm" should be fine.
I'm splitting hairs!

 

The most you should need is one N.O. and one N.C..

The issue is that often a circuit will require separate contacts. ie. No common!

Need access to all 4 terminals if you use circuit similar to my suggestion.

The 25mm showed this 4 terminal, single N.O./N.C. arraignment. This is the ideal contact form for safety switch.

The "2NO2NC is the most they can do on the 16mm" should be fine.
I'm splitting hairs!

If your trying to confuse me YOU WIN! I think I need to sit down and digest this and not try to do that inbetween writing code and managing developers. Would also probably help if I had the different buttons and compnents to experiment with just to see how things respond.

 

I'm sure that I'm making it harder than it has to be.
Maybe someone else could translate.

Sometimes when I go back to read what I posted, I can't understand it myself.

These two switch forms each have one NO and one NC.

But there is a difference!

The second has a common terminal. Because of that, the NO and NC part cannot be used in separate circuits.

To make up for that short coming 2 switches could replace the one.
Using the NO part of the first switch and the NC part of the second.

 

I'm sure that I'm making it harder than it has to be.
Maybe someone else could translate.

Sometimes when I go back to read what I posted, I can't understand it myself.

These two switch forms each have one NO and one NC.

But there is a difference!

The second has a common terminal. Because of that, the NO and NC part cannot be used in separate circuits.

To make up for that short coming 2 switches could replace the one.
Using the NO part of the first switch and the NC part of the second.

I've done that when looking at old code I wrote.

I think I get the general idea in that the relay is controling the fire part of the circuit and is in a condition to not allow the fire current if the key is turned when any of the buttons are not in the open state (not pressed) and that to reset you would turn the key back to unarm to reset that relay as long as the button condition is corrected so that when turned back to fire all buttons are in the open state.

If I am understanding that correctly that is why you want he 2NO2NC buttons with 4 contacts so that the NO and the NC are seperated.

When the buttons are not pressed and the current travels through the NO posts the turning of the key would latch the relay for the fire current so that when the button is pressed it would fire.

Am I getting it or am I way off here?

 

If I am understanding that correctly that is why you want he 2NO2NC buttons with 4 contacts so that the NO and the NC are seperated. Yes

When the buttons are not pressed and the current travels through the NO (NC) posts the turning of the key would latch the relay for the fire current so that when the button is pressed it would fire. Yes

Am I getting it or am I way off here?

"want he 2NO2NC " Or the 1NO1NC with 4 terminals as in my link to the 25mm buttons.

 

Improved circuit using your switch.
I'm not fully awake yet. So I reserve the right to edit later.

This would not be fail safe. However faulty (leaky) or stuck switch shunts indicator, so as the "safe light will be dim or off.

Do not arm until safe lights are all on.

It will also work with the fail safe relay circuit, if switches have two circuits and bi-directional/bi/color leds.

 

I'm working on getting some of the other buttons to try out. Unfortunatly China likes to use DHL and DHL = 99% package loss everytime I've used them. Right now dealing with them the shipper shipped to the correct address but DHL delivered to the wrong address even had the person sign for it at the wrong address and it's been impossible to get them on the phone or return phone calls so having stuff shipped from China is a PITA but I've not found a US based company that makes buttons like this well at least Google hasn't found any more me.

 

I wanted to post my idea asap. The bi-directional leds were a great idea.

I believe you are getting the 3-lead leds this time.

Oh well, back to the drawing board.