# Basic Electronics

Getting started with basic electronics is easier than you might think. This Instructable will hopefully demystify the basics of electronics so that anyone with an interest in building circuits can hit the ground running. This is a quick overview into practical electronics and it is not my goal to delve deeply into the science of electrical engineering. If you are interested in learning more about the science of basic electronics, Wikipedia is a good place to start your search.

By the end of this Instructable, anyone with an interest to learn basic electronics should be able to read a schematic and build a circuit using standard electronic components.
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## Step 1: Electricity

There are two types of electrical  signals , those being alternating current (AC), and direct current (DC).

With alternating current, the direction electricity flows throughout the circuit is constantly reversing. You may even say that it is alternating direction. The rate of reversal is measured in Hertz, which is the number of reversals per second. So, when they say that the US power supply is 60 Hz, what they mean is that it is reversing 120 times per second (twice per cycle).

With Direct Current, electricity flows in one direction between power and ground. In this arrangement there is always a positive source of voltage and ground (0V) source of voltage. You can test this by reading a battery with a multimeter. For great instructions on how to do this, check out Ladyada's multimeter page (you will want to measure voltage in particular).

Speaking of voltage, electricity is typically defined as having a voltage and a current rating. Voltage is obviously rated in Volts and current is rated in Amps. For instance, a brand new 9V battery would have a voltage of 9V and a current of around 500mA (500 milliamps).

Electricity can also be defined in terms of resistance and watts. We will talk a little bit about resistance in the next step, but I am not going to be going over Watts in depth. As you delve deeper into electronics you will encounter components with Watt ratings. It is important to never exceed the Wattage rating of a component, but fortunately that Wattage of your DC power supply can easily be calculated by multiplying the voltage and current of your power source.

If you want a better understanding of these different measurements, what they mean, and how they relate, check out this informative video on Ohm's Law.

Most basic electronic circuits use DC electricity. As such, all further discussion of electricity will revolve around DC electricity.
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halamka says: May 28, 2013. 4:31 PM
When are you going to help make a new "Commodore Computer" ? Microsoft is bad. I don't like "Microsoft" How would you limit sales? Computer people can't work non stop. On any one order sales must see a limit. Microsoft is a bad , limiting program. I think I know how to make the " line number and return " work on a " BASIC " computer.
platinumswag says: May 25, 2013. 10:35 PM
turtledrake says: May 8, 2013. 5:12 PM
Even after years of electronics projects I found this Instructable helpful.
sspence says: May 1, 2013. 7:11 AM
This does not sound correct. The way you are showing is that the center is biased to one side or the other. Just using one side and the wiper is not the same electrically as connecting the wiper to one side.

See http://www.digikey.com/schemeit/#dt8
sspence in reply to sspenceMay 1, 2013. 7:20 AM
For clarification: What happens if the potentiometer fails for some reason (age, poor quality, dirty, etc.)? If the wiper (which is the rotating part of the component and probably most prone to failure) shorts out, it will let the full amount of signal through. By attaching lug 1 to lug 2, we are building in a “fail-safe.” This ensures that the circuit is never completely open—there will always be some resistive path in case the wiper goes south.

earslan1 says: Apr 22, 2013. 5:14 PM
thank you so much :)
I_StarkGuy says: Apr 15, 2013. 11:17 AM
Really good Instrcutable!!
amasinggray says: Mar 11, 2013. 12:29 PM
cool... NOT! just kidding. i like ur instructable!
FadeRat says: Mar 8, 2013. 3:49 PM
Could someone please explain the flow path for this schematic? I don't understand where the electricity goes from A to B to C etc.
guruhebbar says: Mar 1, 2013. 6:45 PM
This is awesome one.... need to start right away.... one more additional explanation to this would be great and that is, in the 2nd project can you please explain why you have used the listed parts? like, why 47 ohm resistor, why 10F capacitir? just to know the way you choose these...
Icanbuildanything says: Jan 30, 2013. 7:27 AM
Thanks for this Instructable. I have a vintage Pilot stereo that blew something out when I hooked up the speakers too soon (it takes it a few seconds to fully shut off) so I have to figure out what needs to be replaced. You can see the lights come on when you turn it on but no sound, which did work prior to the blow out, that came with smoke and a burning smell. It has a record player,8 track, cassette player and radio so I just need to get the sound working again,try to fix the record player and install a cd player if possible. This will be the stereo of all stereos with all those options! LOL I haven't opened it up yet. If anybody can give me some tips that would help. Maybe I'll make my own instructable when I fix it. :) I have a few photos of it now on photobucket, (user: ViewMyPhotosPlease) http://s1308.beta.photobucket.com/user/ViewMyPhotosPlease/profile/
sblauvelt1 says: Jan 17, 2013. 7:02 PM
Thanks for writing this guide. I've been bumbling through but now I understand why somethings work and others haven't.
apower3 says: Dec 12, 2012. 1:10 PM
Never really taken much thought into how great electronics are at school, but I've recently taken a strong interest in it. This is clear and concise and a great start to what I need to know. Brilliant!
JKPieGuy says: Oct 4, 2012. 6:49 PM
Actually these are called "Cells" Batteries are a collection of "Cells".
wadhwavandana says: Sep 11, 2012. 10:27 PM
that's awesome.............................its prove very useful for me
jamfile12 says: Aug 30, 2012. 9:15 PM
thanks for the information : )
I am a nurse And I don't have any idea about electronics.

randofo (author) in reply to jamfile12Aug 31, 2012. 8:22 AM
Converting heat to electricity would involve some sort of generator that runs off the heat... like a mechanical engine.

Try Simple Bots:
http://www.instructables.com/simplebots
miwuc says: Aug 12, 2012. 11:12 PM
I found an explanation of the circuit here http://talkingelectronics.com/projects/FlasherCircuits/Page83FlasherCircuitsP1.html
joy_jorden says: Aug 5, 2012. 3:30 PM
wait why do we need an IC and a diod?
randofo (author) in reply to joy_jordenAug 5, 2012. 8:20 PM
They are just some of the components you might need when building a basic circuit.
joy_jorden says: Aug 5, 2012. 3:35 PM
oh man thank you for creating this my freind eat my brain asking weird electronic question
MackeFeet says: Jul 8, 2012. 7:11 PM
It would be more helpful to tell what the circuit is actually doing in terms of each component.. Just saying build this doesn't exactly help.........
mvanderdeen says: Jun 4, 2012. 4:13 PM
so the middle pin would be wired to the light (or whatever you're dimming etc) and the others are for positive and negative?
mvanderdeen says: Jun 4, 2012. 7:17 AM
i'm very new to this but perhaps you could show how they're wired in the componants with more than 2 sides usualy stop me dead in my tracks
randofo (author) in reply to mvanderdeenJun 4, 2012. 8:16 AM
You can think of it as two resistors wired in series. When you turn the knob one way, the value of one increases and the other decreases. When turned the opposite way, you get the opposite reaction. The middle pin is where the two resistors meet.
livntoasty says: Dec 25, 2011. 3:50 PM
Lemme see if I understand this some (I'm a wee-bit corn-fused, too)
NPN: collector (input?) ---> emitter (output?)
PNP: emitter (output?) ---> collector (input?)
I see 3 pins on the transistors in your pic..from left to right on NPN with part number facing you, are these collector, emitter and ground? If so, are the pins the same in the PNP transistor? If they aren't in a specific order, then how does one tell which is which? Or, are the connections assumed because they perform specific behaviors? In other words, the transistor "knows" the difference between the small amount of electricity and the large amount of electricity?
When I hear the word amplify, I think of sound. I removed the electrical components from the circuit board (car had no body or light covers) and ended up with quite a few transistors. Does this mean that car was designed to include sound? Or, can transistors be used to amplify the energy in non-audible objects? For example, would I find a transistor in a variable speed rc car with no lights or sound?
Taranach in reply to livntoastyDec 26, 2011. 5:37 PM
Actually the pins serve the same purpose either way, Ground is always ground, the collector will always be the "input" and the emitter will always be the "output". The difference between them is the direction of electron "flow". The three letters stand for the polarity between the three layers. A diode has two layers, a Positive and a Negative and would be called a PN junction. Electrons will only flow one way in a diode from P to N. In a transistor there are three, PNP (Positive-Negative-Positive) and NPN (Negative-Positive-Negative) and indicates which way the electrons will flow during its operation.

The pin order will either be marked on the transistor or can be looked up on a datasheet. The word amplify only means "make larger" and is often used in reference to sound but in this case we are talking about the number of electrons flowing through the circuit or the waveform being made bigger. transistors are used to make a signal wave bigger or sometimes to modify the shape of the waveform. In a sound system, the electrons are used to move the cone of the speaker which we perceive as sound, but it can also be used to change the frequency and brightness of light like in a TV or the signals in your RC car to turn or for speed..
colin55 in reply to TaranachMay 29, 2012. 9:22 AM
The BASE is nearly always the INPUT. Never the COLLECTOR.
bmrbill in reply to livntoastyDec 26, 2011. 3:31 PM
Wow. My first instructable contribution. Transistor theory is where a lot of technicians start thinking about other career fields, so don't feel bad if you are confused. The NPN, PNP names come from the way the little silicon germanium layers are laid down. Think of an oreo cookie. The middle (stuffing) is the base. The other two layers (the cookies) are the emitter and collector. If you look at the schematic drawing, the collector is usually on top. The emitter is usually on the bottom. And the base is usually in the middle. Notice I said 'usually', not 'always'. Now, look at the arrow in the schematic symbol. If it points to the base, then the base needs to have a voltage at least 0.7 volts less than the voltage on the emitter for the transistor to be 'forward biased'. If the arrow points to the emitter, then the emitter needs to have a voltage at least 0.7 volts less than the base for the transistor to be 'forward biased'. The first example would be a PNP transistor. The second is an NPN. Forward bias means current flows. Reverse bias mean current doesn't flow. As for the pins, they are in a specific order. A drawing called a datasheet describes which pin is which. A datasheet will usually come with the transistor.

Transistors evolved from the vacuum tubes, which were also known as electron valves. Sometimes it's easier to think of them that way. A transistor can do many things, including amplify. It can act as a switch. And I won't even get into impedance matching.

This could get really complicated. If you'd like to more, let me know.
randofo (author) in reply to livntoastyDec 25, 2011. 9:37 PM
An amplifier is an electrical device for increasing electrical signals. Transistor amplify an electrical signal. Sound amplifiers are amplifying and electrical signal. They are found in most complex electronic devices (sound or not).

To figure out which pin is which on the transistor, you would need to look up the datasheet for the part number that is written on the transistor. The datasheet will have a picture or diagram to tell you which pin is which.

In terms of NPN versus PNP... the PNP is wired with an opposite polarity to the NPN.

So...

NPN --> Collector = power ---> emitter = ground
PNP --> Collector = ground ---> emitter = power
rquinhoneiro says: May 7, 2012. 9:46 PM
Ok, I'll give up here. Such a big move from the last step. Now I really appreciate the use of micro controllers. :( Sorry about my english.
randofo (author) in reply to rquinhoneiroMay 20, 2012. 8:28 AM
nohab says: Apr 23, 2012. 6:14 AM
3.9K is often written 3K9
mctoma says: Apr 22, 2012. 4:00 PM
rock n roll
person% says: Apr 14, 2012. 11:56 PM
thanks a LOT!

just wondering, what is the output voltage of circuit three? I have built this circuit but it didn't work, I guess the 555 overheated. is it possible to blow the 555 while soldering? or maybe my 8 ohm 1 watt loudspeaker was too large.
randofo (author) in reply to person%Apr 15, 2012. 11:01 AM
The voltage is 9V. It sounds like you accidentally shorted the circuit by connecting the positive voltage directly to ground. I would check all of your wiring connections.
ChrisYarrow says: Apr 11, 2012. 4:15 AM
Can't thank you enough for this.

Thanks! :))
cc67 says: Mar 21, 2012. 7:18 PM
tnx a lot... Is the symbol of the potentiometer with 1 pin on the side connected at the middle pin, does this mean you also need to connect it in a pcb?
randofo (author) in reply to cc67Mar 21, 2012. 8:59 PM
It means only two of the pins are used, so rather than creating a sweeping voltage divider circuit, you are just changing the resistance. The pot is only working a variable resistor in the circuit.
cc67 in reply to randofoMar 21, 2012. 11:47 PM
oh that's why the electronic piano I try making from this instructable http://www.instructables.com/id/How-to-make-an-electronic-piano-with-a-555-IC/ doesn't work. Because I connected the 2 pins... tnx a lot
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