# Add LED to 7447 BCD to 7 Segment Display Decoder

#### christw16

Joined May 31, 2018
21
The first picture below is my circuit diagram
It consists of dip switch 4 bits, ic 7447 and seven segment
However
I want to add LED. When I input 0001, the seven segment will show "1", and i want to have 0001 LED just like the second picture
How can I do?
Thank you guys so much!

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#### dl324

Joined Mar 30, 2015
17,142
I want to add LED. When I input 0001, the seven segment will show "1", and i want to have 0001 LED just like the second picture
How can I do?
What do you want that LED to do for other numbers? Specifically, 3, 5, 7, and 9.

#### christw16

Joined May 31, 2018
21
What do you want that LED to do for other numbers? Specifically, 3, 5, 7, and 9.
i only take 0001 as example
yes other numbers are counted

The purpose is I want to add 4 LED.
I should explain in detail sorry
if I have my dip switch to 0000, I want to let my LED turn light to be 0000 as well, the seven segment will be 0
if I have my dip switch to 0001, I want to let my LED turn light to be 0001 as well, the seven segment will be 1
if I have my dip switch to 0010, I want to let my LED turn light to be 0010 as well, the seven segment will be 2
if I have my dip switch to 0011, I want to let my LED turn light to be 0011 as well, the seven segment will be 3
if I have my dip switch to 0100, I want to let my LED turn light to be 0100 as well, the seven segment will be 4
.
..
...
....etc

#### dl324

Joined Mar 30, 2015
17,142
The purpose is I want to add 4 LED.
I should explain in detail sorry
if I have my dip switch to 0000, I want to let my LED turn light to be 0000 as well and the seven segment will be 0
You want to display the switch setting as a binary number using 4 LEDs.

You can add an LED with current limiting resistor in parallel with each of the 1k resistors.

#### MrChips

Joined Oct 2, 2009
31,087
It looks correct to me.

#### christw16

Joined May 31, 2018
21
It looks correct to me.
it is correct.

#### ericgibbs

Joined Jan 29, 2010
19,115
hi chris,
Unless I am missing something, isn't that already doing what you ask.?
E

#### MrChips

Joined Oct 2, 2009
31,087
Are you saying that the photos are not your own and you just want to duplicate what someone else has shown?

Put the LED between the DIP switch and the pull-down resistor.
Note that in the photographs shown, the pull-down resistors are 330Ω.