Do you know what you are doing ?
Hi everybody,
i'm tru and new to electronics...
So Tru, do you understand anything about the electronic circuits you build or do you just build it like a piece of Ikea furniture by following the instructions with no idea why anything is the way it is ?
Why am I saying this ?
You repeated ask about the resistors, but don't bother to mention what they are for .
You posted the text description and completely left out the MOST IMPORTANT part , that being the
title of the section the resistor are part of, namely the ULN2003 circuit.
ULN2003A
Used to pass PWM output to RGB Led.
Resistors (1/4W)
1 470Ω 1/4W (Busy Led)
2 4.7KΩ 1/4W (SDA,SCL lines)
3 1.5KΩ 1/4W (Voltage divider) (*) R1
3 2.2KΩ 1/4W (Voltage divider) (*) R2
3 1KΩ 1/4W (Voltage divider) (*) R2
(*) This resistors are used as a voltage divider to down the 5v output of Arduino I/O pins to 3.4v in my case (1.5k to pin, 3.2k (2.2k+1k in series) to Ground).
You can use 1.8K to pin and 3.3K to ground to simplify, and you will obtain 3.24v . You will need 3 of each.
So let's try to put this all together .
- We have 3 SETS of resistors that form voltage dividers
- "These resistors are used as a voltage divider to down the 5v output of Arduino I/O pins to 3.4v"
- Each voltage divider consists of one 1.5k and ONE 3.2 (or 3.3k)
- One end of the 1.5k goes to " the pin"
What is "the pin " ?
If you look at the board layout you see Arduino digital pins 2,3,4 &5 and 9,10 & 11.
If you do a little research you will learn:
So, Arduino UNO PWM Pins are:
Pin # 3
Pin # 5
Pin # 6
Pin # 9
Pin # 10
Pin # 11
- So the 3 "pins" that need the voltage dividers are PWM pins 9,10 &11
I say this because if it was the other group , then you would need 4 sets, not 3, right ?
- One end of the 3.2k resistor (you can use anything between 3k and 3.2k) goes to GND.
- The second end of the 1.5k connects to the second end of the 3.2k resistor and from
there it goes to the ULN2003.
The purpose of the voltage dividers is to reduce the arduino 5V PWM to 3.3 volts which
then goes to the ULN2003 pins 1,2 &3 , so
PWM pin 9 gets a voltage divider , the output of which goes to pin-1 of the ULN2003.
PWM pin 10 gets a voltage divider , the output of which goes to pin-2 of the ULN2003.
PWM pin 11 gets a voltage divider , the output of which goes to pin-3 of the ULN2003.
uln2003+pwm+to+leds+schematic
I can't find any proof anywhere of a connection between the voltage dividers and the ULN2003.
I am simply reasoning that what information is available suggests that the group of 3 pins that
need the voltage divider is the ONLY group of 3 pins, which are the PWM pins 9,10 and 11.
But I can't find a schematic to prove that. It's just an logical guess.
The only thing we know for sure is that they connect to "arduino I/O pins". Which ones ?
Who knows ?
So that brings us to the question:
Do you know what a voltage divider is and do you know how to make one ?
Do you know how to calculate the resistor values needed for a voltage divider ?
Do you now know WHY the voltage dividers ARE NOT SHOWN ON THE BOARD LAYOUT ? (YES or NO) ?
I don't see any connection between your questions about the resistors (which are related to the leds)
and the original problem of no sound.
(don't know why the image is rotated, but you get the idea..just turn your head sideways...)