Push button switch with "hysteresis"

Question

I am an avid Digikey-goer and I was looking for a push button that I needed for a project. I am unsure whether the phenomena I want in this part is explicitly marked on the product, or searchable on Digikey, or what the feature would even be called.

I am not looking for a product recommendation, I am looking for the knowledge of how to search for and find this kind of device. This means either terminology, tips, or "you can't select a device off of this feature"

I need a push button (NO), but it has to operate in a way where the internal contact has a sort of 'hysteresis'. I want this action specifically and only for this action; the user knows exactly when the circuit closes and opens, by the clicks inside the switch

I've noticed this mechanism in microwave interlock switches, of which I will describe further:

As the user goes to push this interlock switch, the switch doesn't close until there is enough force to overcome the entire spring action. When this force is achieved, the contact inside the device snaps closed in an instant, making a clicking sound, and definitively closing the switch.

When the user releases their finger, the force on the button decreases, but the switch still remains closed until enough force is let off, and then the internal contact immediately fully opens up again.

Basically, I need a switch that clicks when it switches into the on position, and clicks again when it switches into the off position, with each click being directly from the internal contact making the connection.

^ The cheap little black momentary buttons do not have this feature, as they are meant to switch things with their rising edge; Being pushed in. The release of this button is not useful to me, as the click happens at a different time than the disconnect of the switch:

How may I find a push button switch that exhibits the aforementioned hysteretic click feature?

Answer 1

I'm not sure of the distinction you are trying to describe. The 6mm x 6mm tact switch you show and the microswitch both have an audible click when released, and in both cases it will likely be a bit later (some milliseconds) than the N.O. contacts opening.

In the first case it's caused by the internal metal dome contact oilcanning back to the rest position and in the second case it's probably caused by the N.C. contacts slamming together. Here is what the contact inside the tact switch looks like (from this website) - the mark in the middle is where the button presses on it to oilcan it downward and make contact:

The "tact" in the tact switch name is from the tactile feedback it gives you, unlike a membrane switch sans dome which provides no feedback. Many modern membrane switches incorporate a metal or plastic dome that gives you feedback, and in that sense they are much like the tact switch.

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One generic term is "snap action". But maybe @SteveG is right and you are conflating the relatively loud door latch snap action with that of the interlock switch.

If so, its not a characteristic you will find in a common inexpensive component, it's a separate mechanical contrivance and just happens to carry the switch operation along for the ride.

Answer 2

I believe the switch in your cutaway view is called a snap action micro switch or a snap action limit switch.

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