4.4. Power supply

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Del curso dictado por Moscow Institute of Physics and Technology

Building Arduino robots and devices

215 calificaciones

Moscow Institute of Physics and Technology

Building Arduino robots and devices

215 calificaciones

For many years now, people have been improving their tools, studying the forces of nature and bringing them under control, using the energy of the nature to operate their machines. Last century is noted for the creation of machines which can operate other machines. Nowadays the creation of devices that interact with the physical world is available to anyone. Our course consists of a series of practical problems on making things that work independently: they make their own decisions, act, move, communicate with each other and people around, and control other devices. We will demonstrate how to assemble such devices and programme them using the Arduino platform as a basis. After this course, you will be able to create devices that read the data about the external world with a variety of sensors, receive and forward this data to a PC, the Internet and mobile devices, and control indexing and the movement. The creation of such devices will involve design, the study of their components, the assemblage of circuit boards, coding and diagnostics. Along with the creation of the devices themselves, you will perform visualization on a PC, create a web page that will demonstrate one of your devices, and figure out how an FDM 3D-printer is configured and how it functions. Besides those keen on robotics or looking to broaden their horizons and develop their skills, the course will also be useful to anyone facing the task of home and industrial automation, as well as to anyone engaged in industrial design, advertising and art. The course does not require any special knowledge from the participants and is open even to students of upper secondary school. Programming skills and the level of English allowing to read technical documentation would be an advantage, but this is not obligatory. The entire course is dedicated to practice, so the best way for you would be to get hold of some electronics, follow the illustrated examples and experiment on your own. The kits can be purchased here: kits.cyberphysica.ru. Taught by: Alexey Perepelkin, head of Robotics department in the Laboratory of innovative educational technologies at MIPT Taught by: Dmitry Savitsky, researcher in the Laboratory of innovative educational technologies at MIPT

De la lección

Week 4

After going through Week 4, you will be able to connect your device to a network, plan its creation beforehand , control heavy loads, and power your device correctly.

4.1. Week overview0:50

4.2. Submersible pump2:02

4.3. Field transistor and relay6:40

4.4. Power supply6:47

4.5. Planning6:07

4.6. Think first7:46

4.7. Soil humidity sensor2:16

4.8. Where do web pages come from4:10

4.9. How to transmit data to a network11:35

4.10. How to receive a command from a network8:14

4.11. Finite-state automaton5:13

4.12. WaterMe program basics and switch7:18

4.13. Errors that we often encounter7:03

4.14. The longest sketch so far12:31

4.15. How WaterMe works5:20

Conoce a los instructores

Алексей Перепелкин
Руководитель направления развития цифрового творчества
Центр инновационных образовательных технологий МФТИ
Дмитрий Савицкий
Научный сотрудник
Лаборатория инновационных образовательных технологий МФТИ

How can we power, say, the controller’s board?

We usually do it with the help of a USB cable.

We can use the battery compartment which can fit several

batteries.

We can take one Krona battery and connect it to Arduino

directly with a power plug.

We can take a power module with regulated voltage or without it.

The main thing is that the power source supplies suitable voltage for the board.

Let me remind you that for Arduino, as well as for the majority of other boars, including Iskra,

preferred voltage is from 7 to 12 V, whereas permissible voltage is from 6 to 20 V.

Its operating voltage is 5 V, but it has a voltage regulator built in it,

which transforms any input voltage into 5 V voltage.

The only thing is that if you supply input voltage lower than 7 V,

at the pins you might receive a slightly lower voltage than 5 V.

That’s why when we were looking at the description of the pump, I mentioned

that its permissible voltage is from 3.5 to 12 V.

In fact, every component has its own preferences when it comes to power,

and you always need to pay attention to that.

All the modules that we’ve used before and are going to use in the future,

are optimized for 5 V voltage,

because they were initially created for Arduino.

However, let’s not forget that you might come across a device which

has different power requirements.

Besides, you always need to know

how much the current draw would be for the newly connected component.

For instance, you might discover that the pump’s current draw is quite high,

from 65 to 500 mA, but Arduino’s outputs don’t actually allow such current load.

Let’s once again look at the section of Arduino’s socket,

to which power is connected.

Apart from two “ground” outputs, there is one 5 V output.

Ideally, you can use it to power some of your devices,

but you need to remember that this output can only cope with currents not higher than 800 mA.

There is also a 3.3. V output, since the second best practice

for small modules and their components is 3.3. V power.

Here only 50 mA is permissible.

The most intriguing output for us now is Vin.

It is connected directly to the power input, from which power is supplied to Arduino.

This means that if you, say, connect a power module or a battery

compartment to it, all this will be output through Vin.

Moreover, you can connect your plus power pole directly to

Vin and supply power through it to the controller's board.

If you power your Arduino through USB, make sure that

the load of your device does not exceed 500 mA,

otherwise Arduino’s protection tool will be turning the power off in order not to overload the USB port.

If you want to supply high load,

you need to use a powerful power source.

You can solve this problem is various ways: you can either connect the power source to Arduino and supply power through the Vin output, or you can

connect power separately to a powerful power supply.

In the latter case, make sure that all your “ground” poles

are interconnected in your circuit.

If your ground values are different, then your voltage,

i.e. the difference of potential between the “ground” and the “plus”, may turn out to be different.

In some cases, this could lead to some undesirable effects.

Let me remind you once again that you need to connect the grounds if you are using different power sources.

In most cases, however, you won’t need to think about it, since if you are

using some expansion cards, for instance, which allow you to connect some

additional power source, like Multiservo shield,

which we examined in Week 3, everything has already been taken care of.

The grounds are interconnected there, so you won’t need to think about it.

But if you take separately a battery package and a motor,

you will need to connect the power “minus” to Arduino’s “ground”.

By the way,

I have removed one battery from the battery compartment not just because

it’s easier to turn the device off this way, but also because

its wires are loose now, and they can easily close. In this case, we will

see a smoking power module, feel some smoky odor and might even witness the power module ignite.

I have witnessed this several times myself.

That’s why when you are done working with your device,

remove at least one battery.

Now let’s imagine that you want to

connect the pump to 3.5 V voltage, which is quite permissible for it,

and you want to use the same power source to power your controller.

Since we remember that Arduino works in the 6-7 V diapason,

we don’t need to use an additional power source -

we can just use the step-up voltage converter.

It appears as a module in our circuit too,

and it has two terminal blocks: the input and the output.

Between them, apart from the components

which perform this conversion, there is a preset resistor.

This is a resistor which can be rotated in either direction

to control output voltage.

We shall do this next week, and you will get to see how this works in practice.

Let’s sum up: when you start assembling

your device, think about how you are going to power it.

What voltage does each of the components need?

What current will be drawn to this component while it’s on?

Consequently, how exactly are you going to power it?

Will all your components have separate power supplies, or will they just have one common power supply?

If it’s a separate power supply, are you going to connect the ground?

It must be connected.

Once you’ve figured this all out,

everything should work without a hitch, and there will be no need to fear that something might ignite.

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