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When it comes to power switches on PCB, one is the slide switch. When we slide it one way, the device turns on and when we slide the other way, the device turns off.

There is another kind of switch. For this second kind, when we press it and release it, the device turns on. If we press it and release it again, the device turns off. The press and release operation results in the switch always appears to return to the same position. Because of this we can't just look at the switch and know if the connection is ON or OFF.

The problem is that, this second kind of switch is similar to a push button but not the same thing. With push button, a connection is made when the switch is pushed down and released otherwise. However, the mechanical switch I am talking about, toggles its state, each time it is released.

What is the proper name for this second kind of switch? I just need to be sure that when I place order for component, I don't end up with a push button device instead.

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3 Answers 3

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A push button switch, which changes state on being pressed and which reverts to its original state on being released, is known as a 'momentary push button switch'. Additional circuitry is required to obtain the 'on' or 'off' function on alternate presses.

The switch being referred to, that achieves the above function without any circuitry, is known variously as follows:

  1. Mechanical latch 'on / off' push button switch

  2. Mechanical 'push-to-on / push-to-off' switch

  3. Self-locking push button switch.

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  • \$\begingroup\$ have you used some specific brand or component in the past that you could recommend? \$\endgroup\$
    – gyuunyuu
    Commented May 30, 2023 at 9:47
  • \$\begingroup\$ Hi gyuunyuu, Product recommendations are off-topic. You'll get plenty of options when you do an online search. \$\endgroup\$
    – vu2nan
    Commented May 30, 2023 at 10:24
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I would call the switch you want an "alternate action pushbutton", if it is a purely mechanical switch.

However, many things these days use a simple momentary pushbutton, with some electronics to do the actual power switching - but these may require pressing the button for a second or two to turn the device off (or on, in many cases).

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  • \$\begingroup\$ I see, so how does the electronics work for this mechanism to power the device? I mean it seems that part of device is always on and when the switch is kept down for a few seconds, some component turns the power on for the rest of the device. Is this correct? I guess some special IC might be used in this case but am not sure. \$\endgroup\$
    – gyuunyuu
    Commented May 30, 2023 at 9:47
  • \$\begingroup\$ @gyuunyuu: In most cases there is probably a microcontroller and software involved. \$\endgroup\$ Commented May 30, 2023 at 15:50
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There are many names. Nothing is standardized.

Eg. "Alternate action (push on/push off)" is one of the more clear ones. Sometimes "latching" is used (though that's potentially ambiguous)

If the switch is listed as "OFF - (ON) " or "Momentary" it is certainly not what you want.

For example, this part is offered in both momentary (B, D, F, H) and alternate action (A, C, E, G). "ill" stands for illuminated.

enter image description here

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    \$\begingroup\$ When I searched some seller websites I became severely confused to see that what looks like the same part is internally available in "momentary" and also "latching" version. Then this terminology that you explained in an earlier question about (ON)-OFF and ON-OFF difference is another thing. Never thought switches could be so hard to get head around. \$\endgroup\$
    – gyuunyuu
    Commented May 30, 2023 at 9:49

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