Help Needed: Connecting 4-Digit 7-Segment LED to Power Supply and Circuit Diagram Review

Other Hardware General Electronics
1

Hello everyone,

I’ve created a circuit diagram for a 4-digit 7-segment LED display that I’m working on. I’m using shift registers to control the display. However, I’m uncertain about the power supply connection for the LED display. Here are my concerns:

  1. Direct connection to the 12V supply: Should the LED display be connected directly to the 12V power supply, or does it need a current-limiting resistor or regulator in between?
  2. Circuit corrections: Are there any mistakes or improvements you’d suggest for my circuit diagram?

Here are a few details about the setup:

  • LED Display Specs: 2.2-inch size, common anode.
  • Power Source: 12V DC.
  • Control: Shift registers (74HC595) for data handling.

I’ve attached my circuit diagram below. Any feedback or suggestions would be highly appreciated!

Thanks in advance for your help.

Circuit Diagram:

SCH_Schematic SSD_1-Page 1_2025-01-13
SCH_Schematic SSD_1-Page 1_2025-01-131675×1190 58.3 KB

All the Resistor values are 680 ohm
LED data sheet
1811151434_ARKLED-Wuxi-ARK-Tech-Elec-SM412301N_C164872.pdf (289.2 KB)

2

For starters:

image
image645×348 91 KB

Highlight #1: Amazon.com : .1 uf

Highlight #2 refers to your OE pins.

3

There's a perfect chip for this. Unfortunately they are getting rare and expensive, but if you can find one at a price that's acceptable to you...

4

You have current limiting resistors on the cathodes, you don't need or want more resistors on the anodes.

Replace each 74hc595 + ULN2803 with a TPIC6B595.

Add a 0.1uF ceramic bypass cap to the Vcc pin of each chip, whichever chips you use.

1 Like
5

I should clarify. As a beginner, you need a "DIP" chip for building your prototype current circuit on breadboard or protoboard. It is this version of the chip which is now rare and expensive.

s-l1600 (28)
s-l1600 (28)1200×1600 214 KB

There is also an "SOP" type. These are much more reasonable price, but not suitable for using on a breadboard or protoboard.
s-l1600 (27)
s-l1600 (27)1529×1600 219 KB

However, you can buy SOP to DIP adapters:

s-l1600 (26)
s-l1600 (26)700×700 26.1 KB

Soldering the SOP chips onto an adapter is not easy for a beginner. Maybe you know someone with good soldering skills who would do this for you?

I have seen SOP chips offered already soldered to an adapter, but I have not found any available at the moment.

717FV5NWoYL.SL1500
717FV5NWoYL.SL15001500×1201 158 KB

6

Unless you are doing this as an exercise/experiment you can get ready made modules.

Google;

4 digit 7 segment display arduino

Even ones with clock symbols.

image
image1496×763 97 KB

Tom.. :smiley: :+1: :coffee: :australia:

1 Like
7

Your diagram is very blurry, I can't read most of the text and some text is covered by wires and symbols.
If you need to connect something to ground, use the GND symbol

8

Hi, @khalifa_007

It looks like you posted a screen capture of your schematic.
The CAD should let you EXPORT a jpg image that will be much clearer.
You would fine the EXPORT selected under the Files tag.

Tom.. :smiley: :+1: :coffee: :australia:

10

@khalifa_007
Seem like others have also noted as I have allredy pointed out that your image is very blurry

11

Thanks i will make change according to it

12

Thanks, I really like this IC i will definitely look into this

13

I have reupload the image and I have already used ground symbol.

14

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