What is purpose of this resistor

Thread Starter

Englandfengyu

Joined Jul 4, 2021
4
I recent installed a taxi meter to my touran . And I watched the guy from beginning to finish . And I don't understand the use of that resistor . The resistor is used between a pulse wire and 12 v supply wire . Any answer very appreciated . Thanks
 

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MisterBill2

Joined Jan 23, 2018
9,853
It looks like a pull-up resistor for an open collector or mechanical switch. The wiki below refers to open collector where the transistor is used as a switch but the same system applies to a mechanical switch as well - relay, cam switch, or push button.
https://en.wikipedia.org/wiki/Open_collector
A.H. is correct!!! That is a pull-up resistor. It limits the current which is a very important function. The statement in post #3 is justa random guess that is incorrect. Standing time is added by an internal clock when motion pulses are not detected.
 

Thread Starter

Englandfengyu

Joined Jul 4, 2021
4
A.H. is correct!!! That is a pull-up resistor. It limits the current which is a very important function. The statement in post #3 is justa random guess that is incorrect. Standing time is added by an internal clock when motion pulses are not detected.
Thank you very much . Limits the current ? How ? I thought it just pull source to known state .
 
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