Week 9: Output Devices
Group assignment:
Measure the power consumption of an output device.
Document your work on the group work page and reflect on your individual page what you learned.
Measuring Power Consumption of LED
Measuring power consumption is a crucial aspect of assessing the energy efficiency and performance of electrical or electronic devices. Power consumption refers to the rate at which energy is used by a device and is typically measured in watts (W) or milliwatts (mW).
To measure power consumption, you need a power meter or wattmeter, which is a device that can measure electrical power. The basic idea is to measure the current (in amperes, A) flowing through a device and the voltage (in volts, V) across it. With these measurements, you can calculate power using the formula:
Power (P) = Voltage (V) × Current (I) Power (P)=Voltage (V)×Current (I)
For our group assignment this week, we measured the power consumption of a LED.
Note: We must always measure in series, that is, the circuit will be closed through the multimeter, so we must connect it correctly and always on a high scale or where we have the protection fuse (normally 10A).
Equipment Needed:
- Multimeter with an Ammeter function
- Power source (such as a battery or power supply)
- LED setup (LEDs, resistors, and connecting wires)
After gathering all the components, we made the components connection in series where we kept the main power supply from the Arduino which was connected to the CPU.
First we have to turn the multimeter dial to the Ammeter mode.
Then we checked the current from the CPU without any LED or resistors and it was around 2.063 A
Then we tried with the LED:
Connect the positive terminal of the power source to the anode (+) of the LED.
- Connect the cathode (-) of the LED to the positive (red) probe of the multimeter.
Connect the negative (black) probe of the multimeter to the negative terminal of the power source, completing the circuit through the multimeter.
Turn on the power source and allow the LED to illuminate fully.
Observe and record the current reading on the multimeter. This is the operating current of the LED.
Calculate Power Consumption:
If you know the voltage across the LED setup (e.g., 3V for many standard LEDs), you can calculate the power consumption using the formula P = V * I, where V is the voltage and I is the current.
For example, if the voltage across the LED is 3V and the measured current is 10mA (0.01A), then P = 3V * 0.01A = 0.03W or 30mW.
Repeat and Average (Optional):
- For more accurate results, you can repeat the measurement process multiple times and calculate the average current and power consumption.