LEDs: Connect 3 LEDs Without Microcontroller

  • Thread starter Hassan Raafat
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In summary, if you wanted three multicoloured LED's each displaying a different colour, you could use a chip like the LM3914 which can be configured to turn on 1 of 10 LEDs depending on the voltage on a single input.
  • #1
Hassan Raafat
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Is there is a way to connect three LEDs so that there are three cases where one LED only is working in every case of the three without using micro controller ?
 
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  • #2
What are the 3 cases?
 
  • #3
cpscdave said:
What are the 3 cases?
Really I don't know what they are but I wonder it because there are two-color where are green is lighted in forward and red in reverse like that , so can I make the same for three LEDs ?
upload_2016-4-1_18-13-59.png
 
  • #4
I'm still not sure exactly what you are trying to accomplish.
Do you want to have 3 multicoloured LED's each displaying a different colour??
 
  • #5
cpscdave said:
I'm still not sure exactly what you are trying to accomplish.
Do you want to have 3 multicoloured LED's each displaying a different colour??
Not exactly , I want to have three LEDs in one circuit so each time I have a specific condition , there is only one LED working
 
  • #6
What are the conditions then? Hard to tell you what you need to do if we don't know exactly what it is you are trying to accomplish :)
 
  • #7
cpscdave said:
What are the conditions then? Hard to tell you what you need to do if we don't know exactly what it is you are trying to accomplish :)
Not for confusing you that is an idea not a real question in the picture up I have one LED working in the forward and the other is working in reverse bias where the first became off , now the question is Can I make a circuit which have three LEDs where there is one LED working in every case , But also I can't tell you the condition because I really don't know it .
 
  • #8
Hassan Raafat said:
so can I make the same for three LEDs ?
Tri-color LEDs usually have 4 leads. One common (cathode), and 3 separate anode pins:

http://gcdn.indiabizclub.com/uploads05/30/H/5mm-Tri-color104258895.jpg
5mm-Tri-color104258895.jpg
 
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  • #9
Please can you tell me how that works ?
 
  • #10
Your circuit showing two LEDs is incomplete. Something has to make the +V node to go both +ve and -ve with respect to the Earth node. That implies +ve and -ve supply voltages and a switch of some sort.

It's very easy to do what you want if you don't have any constraints. My house has at least 20 light bulbs and I can turn one (any one) on at a time without a microprocessor...but that's because I have 20 light switches.

We can't really answer your question without knowing the constraints. Can you use three switches? One multi position rotary switch?
 
  • #12
CWatters said:
Your circuit showing two LEDs is incomplete. Something has to make the +V node to go both +ve and -ve with respect to the Earth node. That implies +ve and -ve supply voltages and a switch of some sort.

It's very easy to do what you want if you don't have any constraints. My house has at least 20 light bulbs and I can turn one (any one) on at a time without a microprocessor...but that's because I have 20 light switches.

We can't really answer your question without knowing the constraints. Can you use three switches? One multi position rotary switch?
Thanks very much CWatters , So what you said I Can control these switches and control when to turn of the leds on , right :)
 
  • #14
Is three LEDs enough?...

Here is a chip that can be configured to turn on 1 of 10 LEDs depending on the voltage on a single input.

http://www.ti.com/lit/ds/symlink/lm3914.pdf

Can be used in "dot" or "bar graph" modes.

 
  • #15
CWatters said:
Is three LEDs enough?...

Here is a chip that can be configured to turn on 1 of 10 LEDs depending on the voltage on a single input.

http://www.ti.com/lit/ds/symlink/lm3914.pdf

Can be used in "dot" or "bar graph" modes.
Thanks a lot CWatters , I'll read it , you helped me a lot , Thanks again :)
 
  • #16
Hassan Raafat said:
Really I don't know what they are but I wonder it because there are two-color where are green is lighted in forward and red in reverse like that , so can I make the same for three LEDs ?
If you were to power this two-in-one with AC you could have both LEDs glowing 'simultaneously' to give (I'm guessing) a third color: violet.
EDIT: oops, seems that the third color for a R-G led could be yellowish orange, click on customer comments in this link: http://www.allelectronics.com/make-a-store/item/led-6/bi-color-led-2-legs/1.html
 
Last edited:
  • #17
NascentOxygen said:
If you were to power this two-in-one with AC you could have both LEDs glowing 'simultaneously' to give (I'm guessing) a third color: violet.
EDIT: oops, seems that the third color for a R-G led could be yellowish orange, click on customer comments in this link: http://www.allelectronics.com/make-a-store/item/led-6/bi-color-led-2-legs/1.html
That's great :) , big thanks NascentOxygen :smile:
 
  • #19
CWatters said:
Is three LEDs enough?...

Here is a chip that can be configured to turn on 1 of 10 LEDs depending on the voltage on a single input.

http://www.ti.com/lit/ds/symlink/lm3914.pdf

Can be used in "dot" or "bar graph" modes.


Great Video , CWatters , Really thnak you for your effort :smile:
 

1. How do LEDs work?

LEDs (Light Emitting Diodes) are semiconductor devices that emit light when an electric current passes through them. They work by converting electrical energy into light energy through the process of electroluminescence. When electrons in the semiconductor material are energized, they release energy in the form of photons, which is the light that we see.

2. Can I connect multiple LEDs without a microcontroller?

Yes, you can connect multiple LEDs without a microcontroller by using a simple circuit consisting of resistors and a power supply. The resistors will limit the amount of current flowing through the LEDs, preventing them from burning out. By connecting the LEDs in parallel, they can all be controlled individually without the need for a microcontroller.

3. What is the purpose of a resistor in an LED circuit?

The purpose of a resistor in an LED circuit is to limit the amount of current flowing through the LED. LEDs have a low resistance, so without a resistor, they can draw too much current and get damaged. The resistor acts as a buffer, ensuring that the LED receives the correct amount of current and operates properly.

4. How do I calculate the resistor value for my LED circuit?

To calculate the resistor value for your LED circuit, you will need to know the forward voltage and forward current of your LED. Once you have this information, you can use Ohm's Law (V = IR) to determine the resistance needed. The formula for calculating resistance in a LED circuit is R = (Vsource - VLED) / ILED, where Vsource is the voltage of your power supply and VLED and ILED are the voltage and current of your LED, respectively.

5. Can I use different colored LEDs in the same circuit?

Yes, you can use different colored LEDs in the same circuit as long as they have similar forward voltage and current ratings. However, you will need to use different resistors for each LED to ensure that they all receive the correct amount of current. This is because different colored LEDs have different voltage drops, and therefore, different resistances are needed to achieve the same current flow.

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