©2019 Robotics for COMPLETE Beginners

03 Capacitors

 

Probably the most memorable and easily identifiable component you have seen is the capacitor.

These are those longer, fatter, tube like parts usually with an exposed metal top.

You can find these scattered across every board that has a microchip and even in everyday household gadgets.

I found one inside a hair dryer that I did not break by dropping on the hard floor and could not fix.

 

Much like resistors, they are crucial to the guidance and usage of electricity in machines and computers.

 

There may or may not be one inside of you, my advice is to not go looking for it.

 

These are some typical capacitors you may come across.

What is it?

They are made from different materials and come in various shapes and sizes.

 

Common forms are cylindrical, disc, and rectangular.

Cylindrical capacitors are larger and electrolytic with an exposed metal top while disc and rectangular are generally made of ceramic, are orange or beige colored, and are more compact.

A capacitor is two metal plates, each connected to their own wire. Between these two plates is  a thin layer of insulation called a dielectric which can be a solid, paste, liquid, gas, or just empty space. 

 

Many capacitors are non polarized and can be connected either way to positive and negative power.

 

However, electrolytic capacitors like the drum shaped ones will have an arrow on one side pointing to the negative side.

 

These should be connected properly in order to work correctly.  Generally, the longer leg of a capacitor is the positive side.

Here are the symbols you will see on schematics for a capacitor, for now focus on the left:

Looks like a battery right?

That's because it is.

 

It is a rechargeable tank that fills up with electricity just like a tank for water would.

 

When it is fully charged it then discharges all of its electricity.

 

Pretty simple right?

Just imagine one of those big water buckets at a water park that fills up and when full enough it tips over its own weight and dumps all of the water on you and your friends.

 

Imagine it doing this very, very quickly every second!

www.maxpixel.net-Source-Water-Fountain-P

Common Uses of Capacitors

 

Why is this useful?

It can be connected to a resistor so the flow is limited, causing the capacitor to charge up slower than usual.

 

This can be used as a physical, real world timer.

 

Just imagine you have a battery connected to a resistor connected to a capacitor connected to an arm that moves up and down which hits an electronic bell with each discharge coming from the capacitor.

 

This crude example is a basic timer or clock.

 

Pretty cool huh ?

Capacitors have many, many critical uses that you will learn over time and experience.

Some of them include filtering out electrical noise which can interfere with various sensors you will use.

This noise can come from wires being too close, alternating current, audio signals or other wave forms.

 

If this is confusing, try to imagine an ocean of giant, violent waves crashing on the beach.

 

You wouldn't be able to relax unless there was a dam or a wall to catch those waves and when filled up a gate on the bottom opens up because of the pressure of this accumulated water.

 

The water is then released quietly and peacefully and the gate closes until the pool is filled back up again.

When we disconnect the capacitor from its power source the charges on each plate remain on them. Over time the voltage will likely dissipate much like a battery.

 

Don't believe me?

 

Check out the expiration or best used by dates printed on most batteries sold.

 

If I'm right, you owe me 1 December 23, 2017 Bitcoin....I should have sold...

 

If I'm wrong, I owe you 1 Bitconnect token.

There are many other complex things you can do with capacitors and many different forms which you will learn later on.

Just think of capacitors as a weaker, smaller battery which can be used to filter out electrical noise and provide a consistent voltage and current to avoid errors.

Pop Quiz

1.  What does a capacitor do?

2. What is the schematic symbol for a capacitor?

3.  What are three uses for capacitors?

4.  Draw a schematic using a battery, resistor, capacitor and a bell.

Get my favorite books on programming AVR chips I use.

Equip yourself with the most dependable, no hassle, quality usb programmer I use daily.

Make sure you have a basic kit. Arduino is fine, it contains the removable AVR 328p chip we will use.

 

I started with something very similar.

Summary

Capacitors are one of the most simple yet versatile components you will need to spend time with.

 Look at each you come across, compare them, look up their values and relax, you will understand how to use them over time and they will play a powerful role in your projects.

Remember, its just a tank, similar to a battery that fills up and discharges its contents.

You now know what a capacitor is.

You know the basic uses and functions of this simple, cheap component...how it charges up and discharges when full and how that can be used to your advantage.

You learned the various shapes and colors they come in and how to properly connect them to your power source.

This knowledge will be vital when you start connecting sensors and powering DC motors soon.

See in the next lesson!