Hi, guys welcome to electrical projects channel, today I’ll show you how to build simple
but pretty powerful audio amplifier, the key feature of this amplifier that it uses just
one MOSFET transistor.
But also we’ll need a 47K resistor, 4.7uF capacitor, 1000uF capacitor and a 21W 12V
light bulb.
The light bulb can be replaced with a resistor, but finding such powerful resistor is a problem,
that’s why I decided to use a light bulb instead.
Also, we’ll need an audio jack, a heat sink and wires.
Before building it let’s take a look at the circuit diagram,
as you can see it is really simple.
The first step: let’s strip all three black wires and solder to the source lead of the
MOSFET, one black wire I’ll use for powering, the second I’ll connect to
the loudspeaker and the third I’ll connect to the audio jack..
Now let’s connect 47K resistor between Gate and Drain leads of the MOSFET.
Now let’s strip the red wire and let’s connect it to the plus lead of 1000uF capacitor
and let’s solder it to the Drain lead of the MOSFET.
Now let’s solder the plus lead of 4.7uF capacitor to the gate lead of the MOSFET.
Now let’s solder a thin red wire to the 4.7uF capacitor, later I’ll connect another
side of this wire to the audio jack.
As always I don’t have a socket for the light bulb,
so I’ll solder the wires directly to it.
Light bulbs don’t have polarity so it doesn’t mater to which terminals you solder the wire.
And now let’s solder the yellow wire to the light bulb; this wire later will be connected
to the power source.
And now we need to solder the last wire…
we need to solder this brown wire to 1000uF capacitor.
Now, this device is almost ready.
So let’s solder the audio jack to it.
and now let's connect the loudspeaker
In my case I need to solder the wires
So let’s do it.
Now, don’t forget to mount the transistor to the heat sink.
The MOSFET transistor produces a lot of heat so a heat sinks in necessary.
Before turning everything on, make sure that this part doesn’t touch the heat sink or
any other components; otherwise, there is a good chance that you will kill your audio card,
use insulation tape if necessary.
Now let’s connect it to the power source and see what it’s capable of.
Now let’s connect it to the phone and test it.
Well, it works… it is pretty loud.
If you have any questions about this project as always, ask them in the comments below,
and that’s it for today.
Thanks for watching! see you next time.