# lm3915 circuit question

#### zazas321

Joined Nov 29, 2015
936
Heyy. Im new to electronics. I have built 10 led vu meter and want to build 20 led meter^^.But i dont understand one thing- why theese resistors on both sides are connected seperately. I mean why cant 1k and 3,9k resistors be connected like one 4,9k? isnt thats the same?

#### MrCarlos

Joined Jan 2, 2010
400
Hello zazas321

No, definitely is not the same as putting a resistance of 4.9K instead of two, one of 1K and another 3,9K.
These two resistors form a voltage divider.
With a single resistor how would you do ??

This voltage divider is to program the IC 'Telling'
what level of input voltage at PIN 5 turn ON the LED connected to PIN 1.
And
what level of input voltage at PIN 5 turn ON the LED connected to PIN 10.
It is to the measurement range.

Keep an eye to the attached PDF document.

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#### zazas321

Joined Nov 29, 2015
936
but those resistors are connected in series to each other arent they?

#### Dodgydave

Joined Jun 22, 2012
11,235
The two resistors are to set the ref hi voltage and led current, see the datasheet...

#### dl324

Joined Mar 30, 2015
16,672
but those resistors are connected in series to each other arent they?
Yes, but you're using a voltage from the divider.