Isolating push button switches?

[jshhsr]

Is there an easy way to make a group of push buttons work only one at a time? I have a group of 4 push buttons and need to make them so they can not be all activated simustaneously, so they don't pull too much power the the main switch and fry it? Thanks

 

[jshhsr]

also, I am working on PCB inside a somewhat small enclosure so PCB space is at a premium.

 

[MikeHalloran]

When I was a kid, one out of N lockout was done with mechanical linkages behind the buttons.

When I was not a kid anymore, it was done with logic gates.

Nowadays, mostly, all inputs go to a microcontroller, and all outputs come from it, and the only linkage between a given input and a given output is firmware. Which has the advantage of allowing you to easily add extra functions like lockouts, response to button combinations, etc.

But you didn't tell us enough about what's behind your pushbuttons for us to guess what is 'easy'.



Mike Halloran
Pembroke Pines, FL, USA

 

[VEBill]

Conceptually, each switch would also activate a relay that would disconnect the other three switches. Although the wiring is awkward (each switch must be wired in series with three other relay contacts), this may be a practical approach for AC circuits.

For low voltage DC circuits, there are other options.

By the way, if this is one of these industrial wired remote controls, then the added relays ("contactors") need not necessarily be installed within the remote control box. The relays could be installed at the cabinet at the other end of the cable.

 

[dbaird]

You could replace the 4 push buttons with one 4-position selector switch.

David Baird

Sr Controls Designer
EET degree.
Journeyman Electrician.

 

[waross]

One old system was to use Push Buttons with form C (I think) contacts. These are NC, NO contacts with a common terminal. The NC contacts are all wired in series so that when any button is activated, it interrupts the voltage to the following push buttons. The button closer to the supply has priority.
You may use relays wired to seal in once activated and at the same time interrupt the current to all the push buttons. Depending on the inertia of the relay armature and the contact clearances, some models of relays will work and some won't work. The good news is that if a relay does work in this application, all of the same model relay will probably work.
But that's nostalgia talking.
If I had to do this today, I would ask itsmoked to point me at a suitable micro chip and do it in logic. Smaller, cheaper, and more dependable.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[MacGyverS2000]

If I had to do this today, I would ask itsmoked to point me at a suitable micro chip and do it in logic. Smaller, cheaper, and more dependable.

Amen, brother!

Dan - Owner

http://www.Hi-TecDesigns.com