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11 Jun 2010, 03:34
Achint Mehta (2 posts)

Being a pure software guy, hardware seems to be mystic realm for me. I had been reading the section “3.5 Working with Buttons” which deals with basic connections of a push-button. I thought push-button would be a simple device. i.e. two opposing pins are connected when the button is pushed.

However, I have not been able to understand its working. In figure “3.10: A Simple Pushbutton Circuit”, one pin of pushbutton is connected to 5V. However, its opposing pin is not connected to anything at all. However, things don’t work if I don’t connect this pin to 5V. Also, it seems that the opposing pin of the 5V pin is always having some voltage. (I apparently connected a led to the pin opposite to 5V pin and it keeps on glowing whether the button is pressed or not) Is there any relation between the adjacent pins on the push-button as well.

This seems to be puzzling me. Is there any place on the Internet where more info about the internal workings of push-buttons ?


11 Jun 2010, 11:37
Maik Schmidt (120 posts)

Hi Achint!

Believe me: I had the same problems with push-buttons in the beginning.

Although push-buttons have four legs, they are actually two-wire switches, i.e. two legs on each side are connected together inside. The corresponding two wires inside the button are disconnected unless you actually press the button. That’s why the orientation of the push-button is important.

Cheers, Maik

12 Jun 2010, 02:22
Achint Mehta (2 posts)

Hi Maik,

Thanks for your response. After reading your answer the bulb in my head started flickering. Things make more sense now.

In the figure “3.9: A Typical Pushbutton”, top view showed two pins were connected. I assumed that these two ends were connected when button was pressed. (because in my fantasy world switches connected something only when flipped or pressed) After reading your response and touching the led around the different pins of pushbutton, the intricate workings of this mystical device was revealed.

BTW, this is a great book (especially for guys like me). I am having a real fun time following your book (I guess some credit goes to Arduino as well)

Thanks again.


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