10. Output Devices¶
This week’s group assignment was to measure the power consumption of output devices.
Measuring the Power consumption¶
1. Measure the voltage (V) and current (mA) of an LED with a multimeter¶
Measuring equipment¶
Multimeter
Measuring method¶
Voltage: Clamp both ends of the thing you want to measure with a multimeter
LED voltage: Connect the + of the multimeter to the + pin of the LED, and the - of the multimeter to the - of the LED, and measure
Resistor voltage: Measure by clamping a multimeter to each pin of the resistor
Current: Clamp a multimeter between the circuit
(If clamping between the Arduino and the LED, connect the + of the multimeter to the Arduino signal line, and the - of the multimeter to the + of the LED, and measure)
Measured circuit
¶
Each resistor is connected to the LED as below:
(1) 1 resistor
(2) 2 resistors connected in series
(3) 2 resistors connected in parallel
The voltage is 5V and one resistor is constant at 330Ω.
For LEDs, the voltage is constant and does not change even if the current changes.
Theoretical Values
| Number of resistors | Current of the entire circuit | Resistor value | Voltage of LED | Resistor voltage | voltage All |
|---|---|---|---|---|---|
| (1) 1 resistor | 10mA | 330Ω | 2V | 3V | 5V |
| (2) 2 resistors (series) | 5mA | 660Ω | 2V | 3V | 5V |
| (3) 2 resistors (parallel) | 18mA | 165Ω | 2V | 3V | 5V |
Result
| Number of resistors | Current of entire circuit | Resistor Value | LED voltage | Resistor voltage | voltage All |
|---|---|---|---|---|---|
| (1) 1 resistor | 8.2mA | 330Ω | 1.9V | 2.7V | 4.7V |
| (2) 2 resistors (series) | 4.6mA | 660Ω | 1.9V | R1:1.5V R2:1.5V |
4.9V |
| (3) 2 resistors (parallel) | 15.1mA | 165Ω | 2.0V | R1:2.4V R2:2.4V |
4.6V |
It was confirmed that there was no significant deviation from the theoretical values.
2. Check how much the current varies depending on the voltage and the number of Stepping motor¶
Device
A regulated power supply can output a constant voltage.
With a regulated power supply in FLK, the following can flow
- Current: 0-5 A
- Voltage: 0-20 V
- Voltage can be adjusted
- Adjust the current so that the resistance value does not change when the voltage changes (used to ensure that the movement of the device, such as a motor, does not change).
Theoretical Values
- Current increases as voltage decreases.
- Current decreases as voltage increases.
(Since resistance = motor does not change)
(If the voltage = power increases, the current = amount decreases, and if the voltage = power decreases, the current = amount increases, to keep the motor moving in a constant manner according to the signal from the microcontroller) - When the number of motors increases, the current increases
Result
| Current at 9V | Current at 12V | Current at 16V | Current at 19V | |
|---|---|---|---|---|
| 1 motor | 0.14A | 0.11A | 0.09A | - |
| 2 motors | 0.29A | 0.23A | 0.19A | 0.16A |
The following was confirmed
- Current increases as voltage decreases
- As the motor increases, the current increases