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Step 3Figure Out Hardware Requirements
It's important to find out how to plug things in before turning on the power. With LEDs for example, plugging them in backwards and/or without a resistor in place could burn out the LED, making it useless.
The CEM-1203 buzzer used in this instructable will need a resistor as well for the Arduino's sake. Without a resistor, there will be too much current for the Arduino's AVR (Advanced RISC Architecture) to handle. We know this because of Ohm's law, reading the hardware documentation, and asking the experts.
Ohm's Law (and variations)
voltage = current * resistance
resistance = voltage / current
current = voltage / resistance (we're interested in this one right now)
Using Hardware Documentation
According to the buzzer documentation located here, the 'coil resistance' is 42R +- (plus or minus) 6.3. The max amount of current the Arduino AVR can handle is 40mA, found here in section 28.
Asking the Experts
It was helpful to ask experts questions who helped fill in the gaps. To fill in the voltage part of the formula, it is known that the supplied power through the Arduino is 5 volts.
The Resulting Math
current = 5 volts / 42 amps resistance = .119A, or 119mA (milliamps)
Ouch! That makes 79mA too much current for the Arduino. Using the buzzer like this could damage the Arduino long term.
Add a Resistor
We'll need to add a 100R resistor (100.0 Ohms, the 'R' is treated like a decimal e.g. 5R5 = 5.5).
100 resistor amps resistance + 42 buzzer amps resistance = 142A
5 / 142 = 35.2mA
We can work with this! Also, I was able to use a 330R resistor that came with my Arduino starter kit. It's more resistance than needed, and results in a softer buzz. (Special thanks to Eduardo for supplying the 100R resistor used in this intructable!)
Now that the hardware requirements are figured out, it's time to connect things in the next step.
The CEM-1203 buzzer used in this instructable will need a resistor as well for the Arduino's sake. Without a resistor, there will be too much current for the Arduino's AVR (Advanced RISC Architecture) to handle. We know this because of Ohm's law, reading the hardware documentation, and asking the experts.
Ohm's Law (and variations)
voltage = current * resistance
resistance = voltage / current
current = voltage / resistance (we're interested in this one right now)
Using Hardware Documentation
According to the buzzer documentation located here, the 'coil resistance' is 42R +- (plus or minus) 6.3. The max amount of current the Arduino AVR can handle is 40mA, found here in section 28.
Asking the Experts
It was helpful to ask experts questions who helped fill in the gaps. To fill in the voltage part of the formula, it is known that the supplied power through the Arduino is 5 volts.
The Resulting Math
current = 5 volts / 42 amps resistance = .119A, or 119mA (milliamps)
Ouch! That makes 79mA too much current for the Arduino. Using the buzzer like this could damage the Arduino long term.
Add a Resistor
We'll need to add a 100R resistor (100.0 Ohms, the 'R' is treated like a decimal e.g. 5R5 = 5.5).
100 resistor amps resistance + 42 buzzer amps resistance = 142A
5 / 142 = 35.2mA
We can work with this! Also, I was able to use a 330R resistor that came with my Arduino starter kit. It's more resistance than needed, and results in a softer buzz. (Special thanks to Eduardo for supplying the 100R resistor used in this intructable!)
Now that the hardware requirements are figured out, it's time to connect things in the next step.
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Second that means i dont need a resistor?
THANKS! :D