# need help with making led sign

Discussion in 'The Projects Forum' started by djsoheil, Dec 4, 2014.

1. ### djsoheil Thread Starter New Member

Dec 4, 2014
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hi
i am very new here
my job is phone technician
i design the sign which got 5 12v or 9v led light in it.i can make it up to 10 led
i need the light to turn on and off one after each other.
if you guys can help me with the pcb board where to buy one or if you can help me whit design the pcb board it would help me alot.
thank you

May 21, 2014
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3. ### djsoheil Thread Starter New Member

Dec 4, 2014
11
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they are not Parallel or series connection. there is 5 separate led. i want no1 to turn on then turn of then number 2 led turn on then turn of then number 3 led turn on then turn of then number 4 led turn on then turn of then number 5 led turn on then turn of then they start to do same ting from number 1 to 5.
i gust i need to design pcb for that?
i got few ATMEGA328P-PU and ardino to program it
is any one can help me to design Schematics and pcb for that?

Last edited: Dec 4, 2014
4. ### djsfantasi AAC Fanatic!

Apr 11, 2010
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Designing the PCB board comes after designing the schematic. I take it you are also very new to electronics and need help in figuring out how to wire this up.

How long will the LED stay lit? How long will it be off before the next LED lights?

This can be done with a 555 chip running as a clock and a decade counter to light the LEDs.

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5. ### djsoheil Thread Starter New Member

Dec 4, 2014
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the led stay on for 1 sec.1 sec before next led lights.

6. ### ISB123 Well-Known Member

May 21, 2014
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Should be easy to do with arduino and atmega microcontroller. I'll post some code and schematics in few hours.

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7. ### djsoheil Thread Starter New Member

Dec 4, 2014
11
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that would be awesome
when i design the pcb board can i send it to you and yo check it out to make sure everything is ok?

May 21, 2014
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Ok

9. ### djsfantasi AAC Fanatic!

Apr 11, 2010
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This is a simple circuit, commonly known as a chaser circuit. I tried to draw the schematic, but was missing some components, so I found one online. In fact, there are many references online if you search for "4017 chaser circuit". I modified it slightly for your requirements. It is based on the 4017 chip.

Here is the modified schematic. There was originally more LEDs, but I omitted some because you specified one second off between lights.

In fact, this forum has the same circuit in it's e-books (see links at the top of the page). I provided the link here!

A microcontroller is also a good solution, but may be more expensive if you use an Arduino; you'll be spending nfor capabilities you don't need, IMHO. The discrete solution will be a couple of USD.

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10. ### ISB123 Well-Known Member

May 21, 2014
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He can program empty atmega mcu with arduino and then use it standalone in the circuit.

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11. ### djsoheil Thread Starter New Member

Dec 4, 2014
11
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thank you i found diy kit with components but that diy kit comes with 1.5v led !!

12. ### djsoheil Thread Starter New Member

Dec 4, 2014
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i like the idea of atmega
the reason for that in futer if i change my mind i can reprogram it

13. ### djsfantasi AAC Fanatic!

Apr 11, 2010
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Good! Then knowing that requirement, a microprocessor is what you need.

I do have one more question. When you said
Did you mean that there is a 1 second period between LEDs lit, during which nothing is lit?
Or did you want each LED to be lit for one second, then the next for one second, etc..?

Also, when you said the LEDs in the DIY kit come with a 1.5v LED, you seemed surprised. Most LEDs drop between 1.5 and 3 volts (they are run by current, not voltage). I questioned when you said 9v or 12v LEDs. An LED can run on those higher voltages, with the proper current limiting resistor. Remember, LEDs run on current, not voltage. They DO have a property Vf, or forward voltage, which is what they drop and which is used in calculating the value for a current limiting resistor

14. ### djsoheil Thread Starter New Member

Dec 4, 2014
11
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i meant there is a 1 second period between LEDs lit, during which nothing is lit
i didn't know they run buy current not voltage. i know different between current and voltage but can you please explain to me why i.5v led dose not work with higher voltage is it because in higher voltage you get higher current?
i don't know the property vf for them led i got.
but they gone be separately light up and they are not Parallel or series connection in that case dose it matter what is the vf??
please dont get me wrong if i ask you a question i don't want to challenge you or.... i just like to learn more

15. ### djsfantasi AAC Fanatic!

Apr 11, 2010
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Here is a good reference on using LEDs, written by member Bill Marsden. Bill is the local guru in this stuff.

It matters what is the Vf, because without a current limiting resistor, they will likely burn out. There is a slight chance that the LEDs that you bought has a built-in resistor... Do you have a link to where you bought them?

In Bill's blog, he describes connecting one LED and provides this diagram:

Note the 330Ω resistor. That is the current limiting resistor. You need to know the Vf to calculate the value for the resistor.
The supply is 9v and the Vf is 2.5 v. Typical current for a red LED is 20ma. Hence, the resistor is calculated as follows:
$R= \frac{ (V_{cc} -V_{f}) }{I_{led}}$

$\frac{ (9_{vdc} -2.5_{vdc}) }{20_{ma}}=325 \Omega$

I suspect that you have built-in resistors, but if you are not sure, they may get damaged.

Also, you keep saying that they are connected neither series or parallel, but connected individually to your supply. That is a parallel connection, so when and if you look at the blog, you will know what examples apply to you.

Good luck!

16. ### djsoheil Thread Starter New Member

Dec 4, 2014
11
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sorry i don't mean to bother you but i still waiting for the schematics
thank you

17. ### ISB123 Well-Known Member

May 21, 2014
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Not sure if I will be able to do it today because I'm tired.Send me specifications of your LED's and how much LED's are you using?And in which way you want them to light up?

18. ### Bernard AAC Fanatic!

Aug 7, 2008
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The 4017 chaser should work, just connect a LED to every other output; good for 5 LEDs. 4017's can be seriesed per Bill Marsden Index.

19. ### ISB123 Well-Known Member

May 21, 2014
1,240
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You can use 4017 if you want something simple and cheap.Using MCU to control leds is going to be a bit more expensive and complex since its going to need to have a driver which can supply current since MCU shouldn't be used to power anything above 200mA.

Last edited: Dec 4, 2014
20. ### djsoheil Thread Starter New Member

Dec 4, 2014
11
0
this is spec i got from the led
Key Features: LED Light Bulb
Connectpr Type: G4
Luminous Flux: 70-90LM
Output Power: 1W
Input Voltage: 12V
Light Color:Warm White Color Temperature: 2800-3200K
Lifespan: >30000 hour
Material: Aluminum
Dimensions: 3.0 x 1.2CM