Measure the power consumption of an output device

Output devices

The goal of this week is design, fabricate and program an electronic board using one microcontroller and at least one output device like servomotors, leds, speakers, etc.
For the group assignment we have to measure the power consumption of the electronic board that we created, in this case we used two boards, the first board contains a RGB led and was designed by Neil, and the second is the board of Italo Protalongo

RGB

We started with the board with RGB LED. We needed to measure the current with an ammeter, but we had to break the current line and join the ammeter in series, so we decided to measure the voltage and resistance and calculate the current using Ohm’s law (V=IxR).
The first step is to measure the resistance (real values) using a Multitester, then read the voltage of each resistance when the LED is activated. Solve the equation and get current value. The resistance and voltage are measured in parallel, as you can see in the image:

Source: https://www.instructables.com/id/Como-medir-una-resistencia/

Measured values

Resistances

We programmed the RGB led to turn on and off in intervals, so we have to wait until the led is activated to measure the voltage.

Voltage

Once we got the real values of resistors and voltages, we solved the equation (Ohm’s law) and got the current intensity.

Current intensity

DC Motor

Using Italo’s board, we measure the current consumption of DC MOTOR JGA25-371. The value obtained is 0.129mA, this is due to the programing and the encoder that motor has. The motor was programmed to turn on when the input button is pressed.

PWM RGB

Pulse-width modulation or PWM, is a method to represent an analogic output using a digital signal. We use PWM to regulate the brightness of the red led. Then we use an oscilloscope to measure the pulse width in a loop, we can constantly see this regulation.

Below is a video using PWM