hi today i'd like to make a button
yes a button with this button whenever
you want to
you just press the button and you i know
for a fact that a lot of people
prefer rather than well not
you know sometimes in the heat of the
moment you feel passionate and just want
to do it
but if you are quick you can stop
yourself and instead press the
button it could save your career thing
is basically a
will you please stop censoring my words
thank you stop it
i'm just saying bleep a bleeping button
basically i want to make a button that
when you press it makes a bleeping sound
which is like a one kilohertz sine wave
like
what is it good for i was thinking
during live streams or conversations or
meetings even
when you feel angry and want to swear
you can just convey your
feelings by pressing the bleeping button
like holy
you'll get it off your chest and feel
good everyone knows what you mean but
you don't have to actually swear
and people can use their imagination to
feel the bleep with whatever word they
want
what if in their heads they fill the
blank with something
very offensive and you end up getting
cancelled for a bleeping sound
well let me know how it will work for
you now you might think what a boring
project just a button that makes a sound
oh yeah then why don't you go to my
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monthly so use it now let's make the
button anyway
to make this a lot of people just whip
out an arduino board or something and
program it to output the signal they
need
which can be quite beneficial because
you have the flexibility to change the
shape and frequency
we are not here to do software what
you write some code and suddenly you
know electronics
you don't know a damn thing and i still
don't know how to program arduino
so we do electronics this is where my
stash of broken junk
becomes handy because in there i can
find a headset
out of which i can harvest a speaker
here's the speaker
the headset speakers don't output much
audio though they are not made to yell
but let's see i connected it to my
function generator at one volt amplitude
which is the maximum these guys should
take
and
it sounds weak like when you stub your
toe
[Music]
but the main reason for the weakness is
that this speaker doesn't have an
acoustic chamber as
is an acoustic chamber if i'm calling it
right is basically a cavity in front of
the speaker with some holes that the
sound comes out of
all audio products must have it as they
say what an acoustic chamber does is
that it provides some
impedance matching which is basically
helping to pair the very hard surface of
the speaker diaphragm to the very soft
surrounding air
the chamber creates an acoustic pressure
in front of the speaker
that provides a more gradual transition
between hard to soft and maximizes the
energy transfer
but every acoustic chamber has a
specific resonance frequency
just search for helmholtz resonance to
understand it better but
basically the resonance frequency of the
chamber is dependent on the volume of
its cavity and the area of its opening
among other things we naturally use this
by adjusting our mouth cavity and its
opening like
[Music]
adjusting the chamber resonance to the
frequency we want to output
maximizes its volume see my little
speaker
if i put my hand around it
well the audio is already louder but if
i make the hole
smaller it rises to a peak
and if i go any further it becomes
smaller
only at a certain hole size i get the
maximum volume
which is where the resonance of the
cavity is matching my speaker frequency
let's see if i can plot some sort of
frequency response for my speaker
i put a condenser microphone in front of
my speaker that i have to bias
externally i sweep frequencies from the
function generator over the speaker the
microphone picks it up and scope will
plot it
of course it's just for reference
nothing is calibrated here
there we go
[Music]
there and this is what i hear too weak
low frequency response the audio level
rises with frequency but above 10k the
level just drops again
so let's make a chamber for the speaker
i'm going to use a
drug bottle for my chamber because it's
rigid and won't
vibrate with air and in hindsight i
should have called it
a medicine bottle
maybe make it prettier by putting some
electric tape on it
there the sound can still come from the
back of the speaker which is typically
inside a device that has its own cavity
so maybe i use the medicine bottle cap
to cover behind it too
oops i think i put a ton of air pressure
in there release the air pressure
cover the hole again
good very little sound is coming out of
it now
we drill a hole in there
did it make much of a difference let's
do a frequency response
[Music]
not much at all we need more holes
damn it i just cracked the whole thing
let's see the frequency response of this
look at this our misfortune actually
created a
lucky bump at around one kilohertz that
we needed
just listen to it
pretty loud eh well to test a bit more i
covered more than half of the hole with
some
flexible electric tape and see it pushed
the peak down at one kilohertz
and send it further towards lower
frequency maybe a
bit larger hole helps a little bit
better yeah i just cut the opening a
little bit wider
like this look at the massive peak at
one kilohertz
and it seems we have some peaks at the
harmonics too which is fine
our speaker volume without the chamber
was more like this
and now it's like this and of course now
we can make it even louder by
increasing the voltage amplitude
such high voltages would typically be
above the rating of the speaker and
could damage it if applied continuously
but in my application i only momentarily
use it
see for example here i have a 12 ohm
half a watt
resistor and i'm gonna put 12 volt
across it which means 12
watts of power 24 times the rating of
the resistor
but if i do it momentarily the current
reading is off actually
pick see the resistor is still alive but
if i do it continuously
that's when the resistor gets damaged so
as long as we do it momentarily
we should be fine here in my application
i want the chamber resonance to match my
sound frequency because i want the
maximum level but in typical voice and
music speakers they push this resonance
frequency outside the audible frequency
band by reducing the chamber volume
and increasing the hole size this is
because we typically want a flat
response
not a bulge erected in the middle of our
pant
band now it's time to drive this circuit
i'm going to put a simple circuit
together and then i'll
explain it
[Music]
damn it i guess it will grow back and
it's done
it runs on two double a batteries with
switch and everything
and works perfectly the circuit is quite
simple
if you are an electrical engineer so the
circuit is powered by
two double a batteries through the
switch and capacitor
of course there is no reverse polarity
protection so we better
not plug in the batteries backwards and
then we have a schmitt trigger
oscillator circuit that creates a square
wave here and a triangular wave there
and we take the triangular wave because
it's much easier to filter into a sine
wave we use a simple low-pass rc filter
to turn the triangular wave into a sine
wave which also
drops its amplitude so we need a game
stage to bring the signal level back
up and feed it into the speaker and
here's the list of component values if
you care to know
here's the square waveform of the
schmitt trigger
and the triangularish waveform
that is filtered into a sine-way-wish
waveform that is
amplified and i can also use a foot
switch
to keep my hands free when i'm swearing
good man
okay let's try it once someone told me
you'll wake them up tomorrow get your
together and finish what you started or
i'll slap the
out of you and i told him who you think
you are
trying to dictate my life and he said
i am you
it works see there you thought it was a
simple project and yet you learned a ton
from
it and you'll learn a ton more if you
visit my sponsored curiosity stream
i especially found this documentary on
the history of electricity
quite interesting it shows those
primitive awesome experiments we don't
do much anymore and
really brings me back to the roots of
electricity
and gives me some good video ideas too
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