Several common problems with push button switches:

What kind of switch specification is "press once to turn on, and press again to turn off"? What does "with segment switch" mean? I don’t know which function switch to choose for this circuit? Self-locking and reset are still a bit unclear?

How to confirm the key points in the selection of the metal button switch «switch function, switch action». It will be explained in 2 paragraphs:

• Self-locking Reset is the [action type] when the switch is pressed
• NO NC is the [contact combination] of the switch

Self-locking Reset is the [action type] when the push button switch is pressed

Switch function Operation Type: Reset Momentary

Switch combination Contact Type: 1NO 1NC 1COM

Switch function-reset and switch combination-1NO are placed in different parameter items, and the two are also independent.

The switch function is divided into two types: reset type and self-locking type.

It is a switch action type. It refers to the follow-up action of the internal mechanical structure of the button after you press the switch; after the hand that presses the switch is released, if it does not bounce, it is "self-locking";

Switch combination NO normally open contact (SPST-NO), NC normally closed contact (SPST-NC) or COM common contact

Indicates the combination of switch contacts/contacts. It refers to what kind of switching circuit this switch can use. Metal push button switches usually have three contact circuits: NO, NC, COM.

Reset action: press to power on, let go to power off. Let go, the button will rebound and return to its original state

There are many names for the reset type, but they all refer to the same return action. The various ways of writing are as follows：reset, self-reset, self-reset, instant cut, no lock, no segment, instant, automatic rebound, push button，Momentary, Non-lock.

The reset switch is usually used as a trigger signal, that is, it only provides a momentary conduction signal to the back-end line when it is pressed. When the hand is released, the internal mechanical structure of the switch will bounce the button back to the original position. Inside the switch, The contact will also return to the initial disconnected state.

The doorbell can be said to be a typical reset button. When the hand is pressed, the doorbell will ring;

Self-locking push button switch

Action: Press to power on, and it will still be powered on after you let go, and will not be powered off until you press it again.

The push button switch needs to be pressed twice before it rebounds and returns to its original state.

There are many names for self-locking, but they all refer to the same self-locking action. The various ways of writing are as follows:Self-locking, locked, segmented, alternating, self-holding, holding, self-holding, maintained, Latching, Latch-in, Self-Hold, Self-Locking.

The self-locking switch is usually used as a continuous and long-time conduction signal or the power supply of the loop to the back-end line, and it will not be disconnected until the second press.

The self-locking button switch is similar to the commonly used pressing ballpoint pen. There is a set of mechanism tenon/metal hook inside. When the button is pressed, the metal hook will slide along an asymmetrical heart-shaped groove, and the two tips of the heart-shaped groove correspond to The lock and release position of the switch; the action of locking and releasing is repeated back and forth.

It is worth mentioning that because of the extra set of tenon structure, more space is needed for placement, and the length of the self-locking button switch will be longer than that of the reset button.

1NO ▪ 1NC is the contact circuit of the switch

NO normally open contact circuit: the initial state of the contact is open/disconnected/non-conductive Normal Open

There are several common names for NO normally open contacts, but they all refer to the same contact combination. The various ways of writing are as follows:

Normally open contact, a contact, single pole single throw, closed contact, front contact.NO, Normal Open, SPST-NO, Break, front contact.

A group of NO contacts is composed of two contact points, which are usually open/non-conductive, and become closed/conductive when the switch is activated (pressed).

As shown in the schematic diagram of the NO contact in the blue block above - when the button is pressed, the normally non-conductive NO contact will become the opposite closed conduction state. 

Since a group of NO contacts is composed of 2 contact points, 2 terminal pins will be pulled out at the bottom of the switch to allow users to wire/weld wires, so the metal push button switch must have at least 2 terminal pins (2 Pin) to achieve on/off function. A group of normally open contacts 1NO is 2 feet.

NC normally closed contact circuit: the initial state of the contact is closed/contact/conduction

There are several common names for NC normally open contacts, but they all refer to the same contact combination. The various ways of writing are as follows:

Normally closed contact, b contact, break contact, rear contact, NC, Normal Close, SPST-NC, back contact.

A group of NC contacts is composed of two closed contact points, which are usually in the closed/conducting state, and when the switch is activated (pressed), it becomes an open/non-conducting state.

When the button is pressed, the normally conductive NC contact will become the opposite state of disconnection and non-conduction.

COM common contact circuit: The contacts include a set of normally open contacts 1NO and a set of normally closed contacts 1NC

A set of COM common contacts usually has three endpoints representing normally open NO + normally closed NC + common point COM (as shown on the right in the figure above), which is equivalent to leading out three terminal pins as a contact combination. Whether NC or NO is used, there will be An endpoint is used together with the COM point. We will mark such a set of contact combinations as 1NO 1NC 1COM.

When the button switch is activated, both the NC and NO contacts are changed to the opposite state at the same time. The general-purpose Φ16 and Φ19 usually have a preset terminal pin of 5 pins, and you can see that there are two units:

Switch contact combination: a set of contact combinations of three terminal feet (1NO+1NC+1COM)

LED lighting terminal feet: two terminal feet for single-color LED lights

The above is the introduction of the self-locking and reset function of the metal push button switch.