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What is function of the resistor??

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ilikebbs

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Hi, anybody can tell me what is the function of the resistor.

As I know that usually a diode is used for the inversed DC input.
 

rikie_rizza

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I think pin 3 is for detecting if any jack is inserted. When it does, the arrow would not touch the negative terminal.

So, in a case like this, the R is just to avoid short circuit if... the positive and the negative terminal touch the inner contact of the socket but the jack hasn't plug in completely.
 

bhanupratap56

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its very simple man ......
resistor is to draw the current 4m the voltage source when 3 is detecting any device thus grounding the arrow..
it is because if u connect any voltage souce directly to ground then there will be short ckt !!!!!!!!
 

FvM

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Actually, I didn't understand all thoughts that have been expressed previously, but no problem.

A similar resistor for sure isn't generally used with DC input connctors. I have designed a lot of devices, that never needed it. So it must have a particular purpose. Not knowing the remaining circuit or the application, I can only guess.

It could be, that the circuit has a design flaw and get's damaged when connected to a switched-off power supply but the device has it's internal decoupling capacitors yet charged. The resistor could prevent this by discharging internal capacitors. Also other device properties may require a complete discharge of input voltage.
 

Iouri

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Also if device has a sleep mode device is acting as load for incominng power supply to keep it warm
 

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