Episode: 159
Title: HPR0159: Basic Electronics
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr0159/hpr0159.mp3
Transcribed: 2025-10-07 12:33:02

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show and it's awesome goodness. This is a community supported which means yes even I count
because just me being a flesh bag and like being here I'm there for like community and
get to record into my microphone and yeah so woo hoo. Today I want to talk about electronics
so I want to just kick back take it easy and have obviously just another laid back and
fun episode so hopefully um maybe over the weekend or on your way home or whatever this
is going to be kind of just a laid back Ramline episode so when you're at a couple
minute well more than a couple minutes but when you get some time and you want to sit
back and listen hey I'll be here and we can talk about the basics of electronics okay
so okay cool all right here we go we're going to talk about electronics so basically I
need to specify that obviously electronics works off electricity and electricity comes
in two forms you've got AC and DC AC would stand for alternating current and DC would
stand for direct current and that's about as far as I'm going to go into it here today
all the stuff we're going to be talking and referencing and the form of electricity is
going to be DC which means direct current and as far as keeping it simple that's we're
talking about batteries basically anything that is coming out of the battery if you're
not plugging it into a wall meaning it's running off a battery yes even your car that's
DC now your alternator that's AC but you're battery anything that's battery powered yourself
on whatever that's that's all DC and we're going to be talking about electronics which means
low voltages and today specifically we're going to be talking about systems that you use five volts
or less so your car yes it has a battery and it's running DC but that would be called in
the electrical system that knows the difference on the end electronics electrical so you just
kind of learn a nice little what kind of general rule of thumb kind of tool so if you hear
somebody say electronics they're usually talking about something that's lower voltages as opposed
to something that's electrical and electrical can kill you whereas electronics it can make
like I said put your pants make you day not so happy but it's not going to kill you hopefully
so but today we're going to be talking about like I said low voltage systems five volt systems
because we're going to be talking about low logic gates oh logic gate oh yeah and awesomely there
are seven logic gates yeah so basically before we start talking about logic gates before we
even start talking about logic because whoa buddy you and logic danger stuff here like see I
just moved that metal thing away so I can't bang it anymore yes you yeah you in the back you are
welcome I'm sorry man so where was that okay so we're going to be talking about logic gates but
before I guess I can really jump into logic gates because logic gates are kind of a foundation of
you know how electronics today work and kind of the grandfathers of stuff and what we've built upon
so me being a person who enjoys electronics that's kind of one of the things that hopefully
with today's episode and my rambling along is that hopefully you know as you open up your computer
or see some kind of other electronics like the quote unquote guts where you see the little grain
PCB board and all the little black components and stuff well hey remember like those little black
right rectangular like chips yeah those are icy chips that's named for integrated circuit chips
and logic gates kind of compose up you know a family of those looking chips so you know hopefully
man listening to me ramble on a little bit and a little bit more each time we can learn a little
bit more of what's going on inside our systems and hopefully get a basic understanding of
electronics and the systems and what's going on so basically in talking about logic gates we're
going to be talking about a digital system and a digital system as I'm talking to a computer user
hopefully I don't know somebody listening to hacker public radio see I make the assumption I assume
we know what happens man don't do this okay so there's two kinds of systems in electronics we have
digital and analog digital is a yes or no it's on or off it's higher low it's one or zero where
analog analog can come in any shape size or form and berries it's it's crazy man it's analog
it's chaos so this whole digital is the only thing that separates between you and me and
analog chaos so let's give a better example of what I'm talking about so if you will
here we have a good example of a digital system we either have a tone or silence it's either
a high or a low it's either on or it's off this is a discrete system so it's either something
or it's not it's like a light it's either on or it's off so this is a good way to kind of think
of how a digital system exists now we have the sound of chaos this random noise we hear in the
background this represents the analog signal where before we had a series of tones now we have
noise everywhere so now in a sense of silence that noise to go and pick out a signal is very
different than going out and picking a signal in the digital system so with that little bit of
example given we're going to today to talk about a digital system which is much easier to deal with
obviously because it's either a tone or silence it's either on or off it's high or low it's a
one or a zero so it's either true or it's false so you'll hear a lot of different terminology for
digital systems and how they function depending on what kind of person is designing the system
and a lot depending on age as well an older person may be in more inclined to say true or false as
opposed to higher low or myself who I constantly want to say one or zero because being involved
with computers you're looking at you know the computer and ones and zeros and you know the matrix
and little green ones and zeros flying everywhere so if we're going to talk about a digital system
of course we have to have a way to deal with all these ones and zeros a series of tones and
silence it's just a series of tones and silence and as we have something to do with it we're
a way to analyze it and do something based on these conditions which kind of sounds a little
bit like logic we're getting dangerous so with a little bit of logic here we're going to step
into the world of logic gates i'm going to apologize to the guy in the back and
oh the first logic gates we're okay i'm putting it down okay there are seven logic gates
and basically logic gate has at least two or more inputs except for one there's one
exclusion but we have an input and based on an input we have a logic that says we do
something based on what the input is so our first example the first gate is the AND gate
like you and me yeah the AND gate so basically you've got at least two inputs for the AND gate
and it has one output so in order for the output of the AND gate to change state say to go from a
zero to a one or from silence to a tone then we have to have a change of states on all of the inputs
so whether you have two inputs or you have insert in number of inputs in order for the output
of the AND gate to change all the inputs must change and so in digital system this means
all the inputs go from zero to one or high or from low to high and then when all the inputs are high
thus the output is hot and that is the AND gate i hope i'm doing an okay job of explaining this
i'm probably butchering it but i kind of nervous on how to explain it so i'm going to go to the next
gate so the next gate is the OR gate the OR gate has at least a minimum of two inputs i think
you're going to have two or more but i've got to have at least two for the OR gate now the OR gate
it's a little less picky than the AND gate so if we have a change of state on either one of or
any of the inputs on the OR gate then the output will change and so if we have one or more
changes of the inputs then the output changes so it can be one it can be two it can be all of them
but at least one of them has to change and then the output changes on the OR gate
the next gate is the NOT gate and the NOT gate is pretty much the inverter so in this has one
input and one output and it's the basic and most simplest of the gates the NOT gate pretty much
reverses whatever signal comes in so if you're getting a high coming in it's going to output a
if you get a low input it's going to output a high which is pretty much reverses whatever's
going in so that's pretty simple the next gate is the NAND gate which is AND with an IN in front of
it so that's IN a IN D Nancy Alpha Nancy Donald NAND but the NAND gate works the exact opposite
way of the AND gate so basically has a little inverter on the output basically a NOT gate
on the output of the AND gate but it's called a NAND gate so in order for the state to change
on the NAND gate the output is always high assuming that there's no change of state on the inputs
in order for the state of the NAND gate the output to drop to a low then all the inputs have to
be a high so they all have to be one they all have to be true you have to have a tone whatever
analogy we're going to use they all have to have an active input in order for the output
to be nothing or zero or false so that is the NAND gate the NAND gate is basically it's the
actual it's been referred to as the mother of all gates really you can do any of the gates with
a NAND gate the NAND gate really is probably the most common one used of the logic gates because
one way or another you can do what you want to do also as a sad note if you are interested
to this point I'm assuming you are if you're still listening you just you're glutton for
punishment do a search on google videos for the the string that you want to search for is
from NAND to Tetris in 12 steps and basically it's a talk from an MIT professor who basically makes a
small computer out of NAND gates out of logic gates so yeah logic gates are really powerful
depending on how you want to use them that's kind of an extreme case but it's very interesting
because using all these logic gates basically well using NAND NAND chips to make logic all the other
logic gates and basically everything else to have a small computer that actually can play Tetris
along with some other stuff it's very impressive but we're going to continue moving forward now
with the other gates because we have covered four of the seven logic gates so the next gate is the
nor gate it's in OR that's Nancy or well Richard nor and the nor gate is basically the inverted
or gate so it's basically the opposite rules apply of the or gate just like the NAND and the
same thing for OR and NOR so the output of the nor gate is going to be high unless all the inputs
of the nor excuse me bring it back back up let's try again my friends the output of the nor gate
is going to be high unless any of the inputs change so if the inputs go from 0 to 1 on any or
all of the inputs then the output of the nor gate will go to low 0 false so that's basically how
the nor gate works the next gate is the XOR gate which is the letter XOR so XOR is how we
pronounce and how I pronounce it but the XOR gate works like the OR gate but it's a little bit
more picky so the XOR gate works on it's going to have the output is going to be 0 where it's
going to be low as long as none of the inputs or just oh none of the inputs or all of the sorry
I'm trying to remember I have to do my little finger thing and you can't see my finger thing
in any way in order for the the status of the XOR gate output to change we have to have
one but not all of the inputs change so say you've got two inputs and one output for your XOR gate
as I mumble along trying to describe we got two inputs and one output if you've got a change of
signal on one input then you're going to have a high output but if you have a change of state or
high input on both those inputs then the output drops to 0 or goes back to the same thing as if
none of them were active the last gate is the the XOR is going to be the last gate in this rambling
pummeling series of logic gates with no logic host but the XOR gate is the opposite of the XOR gate
so the output of the XOR gate is going to be high assuming that there's no input or we have a high
input from all the inputs so if we have a change of status on any of the inputs but it's not all
of them then the output is going to be 0 and I'm going to go ahead and stop right there with my
beautiful variable descriptions of the logic gates and basically basically that's what is going
on with the logic gates logic gates are very useful in electronics because for example you can use
interface them up with different sensors to be able to know what's going on so you could have for
example a daylight sensor that is a perfect example of a not gate that's pretty much an inverter
so if the daylight sensor senses sunlight then it turns your light off to consider electricity
because you don't need to have a light on during the daytime but at nighttime in the absence of
sunlight then it turns on the light basically an inverter of its input that's an easy example
we'll stick with that one another way that logic gates can be represented is in truth tables
and it's kind of an easier way to kind of as opposed to listen to me ramble about what
a logic gate is and how it works you can also do like truth tables so basically if you want to play
the home game take a piece of paper here let's just get our piece of paper here I've got my paper
and it's your ink pen pencil will equal for all copies your pen or pencil here we go and our piece
of paper feel like a certain radio host and I formulate nicotine strength hands okay but uh so
at the top of our piece of paper here let's write the letters a b and y okay and a and b are
going to stand for our two inputs and y is going to stand for our output and this is kind of a
standard uh how you write up your inputs and outputs for a logic gate so all your inputs they start
with a so if you have let's say four inputs they would be a b c and d and your output is y because
that's your output um that's that's how that rolls so let's say let's take our example and we've
got a b and y at the top of the piece of paper now let's draw a line down the page in between each
letter so now we've got a a row we've got a our column uh we've got a b column and then we've got
a c we've got a b and y column and then underneath each column we can have um basically a truth table
of ones and zeros representing the states of whatever gate we want to make the truth table of
so let's do the AND gate a and d the AND gate the first one that we talked about and so if we're
going to do the truth table for an AND gate if a input was zero saying there was no input on a
let's let's write it zero underneath the first column for a there in that first row and no input
on b then the output y is going to be zero so our first row is zero zero zero next row let's put
an input on a so we'll write one and then we'll have no input on b with zero and then our output
let's going to be zero because there's a high on only one of the inputs so our next row will have no
input on a but we'll have an input on b and then our output y is still going to be zero because
there's only one input and we have our only one change of state on one input and we have two
inputs so for our next row let's write a 1 under a and then let's also write a 1 under b
representing we have a high on both our inputs thus y is going to be one our output
because we have a change of state on all of our inputs so this is a basic truth table if you've
been playing the home game and you know if you look online if you do I search for logic gates if
you are so interested by this episode and you want further knowledge doing simple search you're
going to find a lot of complex things you want to look for electrical systems electronics
keep in mind you know look for digital logic you know that kind of stuff as some of it can get a
little overwhelming if you start looking in the wrong areas so keep that in mind but that little
home game that we just did there that's how you can make the truth table for basically any kind
of logic gate and however kind of system you've got set up another way to deal with this is
something that's known as boolean algebra and boolean algebra is a way to set up formulas and
equations to deal with tying together a whole bunch of different gates if you start tying together
nan gates and or gates and depending on what you want to happen in what kind of scenario and
what kind of senses you have feeding input whether they're going to alarms or lights or you know
rotate or you know what no telling it's it's your situation so in order to write a you know a nice
little equation depending on what you want to happen based on what kind of input you can use
boolean algebra and boolean algebra is kind of I don't know it's kind of a weird twisted form
of algebra but it's really not complicated I know the first time that we went over in school
everybody seemed to have a real hard problem with it nobody really liked it but once I kind of
got it got a little trick to it and it felt like a little game and went once you get it down it
I don't know for me it was like a little puzzle game I really enjoyed especially when we had large
test segments devoted to boolean algebra it was it was kind of easy money you know it was hey let's
play a game and get a high score on the test but also as I mentioned earlier when I talked about
the little black I see the black rectangular I see packages those right there those are
integrated circuits those are also what we would call TTLs which stands for transistor to
transistor to logic and basically each one of those little chips can have multiple gates inside
and there are there are many common packages the packages is another way of referring to those
little black sea chips come packages so there are very many packages that are common out there
so if you were to say go down to your local radio shack and walk into the back where they have
all that the scary bins and you know the real skinny bins which you slide open and they got all
the weird electronic components and stuff and you know it seems like there should be tools or
something in there you know but they're they're way too flimsy and kind of scary because they're
all the way in the back and you know I don't want to go back there because people then you might
be making bones or something scary but that's where all the cool stuff is so if you go back in
there and you know you should look look for the little drawer that has something like TTL on it
or something like that and you know see some all kinds of different I see some packages and
stuff like that in there and if you look in there you may see some that are like the 7400 series
these are the it's the family for logic gates and stuff like that so the most common is the 7400
which is the NAND gate and the 7400 is a little I see which has 14 pins and contains four NAND gates
in one little chip so that's kind of neat and from there I said the family goes on I'm not going
to sit here and read out you know the the whole family of I see components because that would just
get terribly boring but basically it just expands from there and really from here we can kind of
if you guys want this is all right and make some kind of sense you know this is kind of a basic
foundation of of electronics and basic digital systems and from here you have to you have to
test you can from here you have a basic foundation start building upon higher ideas such as like
clocks and memory and being able to do other things based on other input and stuff like that so
logic gates are just wonderful ways for handling inputs and outputs and doing stuff based on
other stuff wow okay so I think I've rumbled on long enough thanks for listening you guys have
a great weekend I hope you guys have enjoyed me listening talk about electronics you guys that
asked for you asked for it so I hope it was all right if you guys want to hear more let me know
I can rumble on for electronics more and more or hopefully if I can adjust any advice whatever
go more in depth whatever just keep doing it however let me know and we'll keep doing it because
I love electronics and if people are interested in how to do stuff whatever and if I can help
you know please let me know because hey electronics and hardware is awesome so thanks to all
you guys at right the awesome software but I love the hardware so until next week you know
this has been Hacker Public Radio neither baby
thank you for listening to Hacker Public Radio
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