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How to Make a RGB LED Mood without Microcontrollers (with 3 led, 3 potentiometers ) I would like a schematic circuit? Answered



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AndyGadget

Best Answer 7 years ago

To get the maximum range of brightness, work out what value resistor you'd need for each colour LED from the voltage drop (Vf) and maximum current (Ifmax) - There's a calculator HERE.  You'll also need to enter the supply voltage you're running from.  You need the resistors in the circuit to limit the current in the minimum pot position and prevent damage to the LED.
Use 250R (or 500R) pots and connect the centre pin to one of the end pins.  Now wire the relevant LED and resistor to this so you've got the pot, the resistor and the LED in series.  Do this for the other 2 LEDs and then wire each of these circuits across the supply.
You can now adjust each LED over the full range of brightness without fear of damaging it.

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AndyGadgetAvadhut.Deshmukh

Answer 7 years ago

 
Yes, and 3 resistors to protect the LEDs from burning out.
(Although it's more variable current than variable voltage.)

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AndyGadgetAvadhut.Deshmukh

Answer 7 years ago

 
All the information you need is in my answer :-
Look at the specification of the LEDs you're using.  The red one will be something like Vf = 1.8V,  If = 20mA.  Put these numbers into the calculator I've linked along with your supply voltage and it will come up with the value for the resistor (for example 180R if you're using a 5V supply).
The circuit for each LED will be exactly the same as the calculator shows you, except you'll also put in a potentiometer in the circuit as well, like THIS.
What voltage are you going to be running it from?

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frollardAndyGadget

Answer 7 years ago

I'm really glad you answered this, because I would have broken the 'be nice' policy telling him/her to search in less friendly terms.

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AndyGadgetfrollard

Answer 7 years ago

 
I was saving him finding the usual arrangement which wires a 10k pot or similar to the led so you get nothing, nothing, nothing, sizzle!

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steveastrouk

7 years ago

Andy's answer only holds for very small LEDs and not the modern high brightness ones, be careful.

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steveastrouk

7 years ago

Use this circuit, and make three of them, right now.

Copy of maths.jpgLED driver.JPGLED driver.PNG