{title2=BJT}
{title2=1948}
{wiki}

By <William Shockley> in 1948 also at <Bell Labs Murray Hill>.

As of 2020, not used anymore in <logic gates>, but still used in <amplifiers>.

\Image[https://upload.wikimedia.org/wikipedia/commons/6/6b/NPN_BJT_%28Planar%29_Cross-section.svg]


Bipolar junction transistor

{wiki}

\Video[https://www.youtube.com/watch?v=_2By2ane2I4]
{title=How a quartz watch works by <Steve Mould> (2017)}
{description=Mentions <feedback loop> loop with the <quartz> <tuning fork> for the <piezoelectricity> and an <amplifier>. Also mentions the choice of 32768 <Hertz> ($2^{15}$) as the first power of 2 that is outside of the <human hearing range>, and then how a <frequency divider> is used to reduce the frequency to get the <second> counter.}


Quartz clock

{wiki}

A <solid-state> <electronic switch> and <amplifier>.

Although transistors were revolutionary, it is fun to note that they were just "way cheaper and more reliable and smaller" versions of exactly the main functions that a <vacuum tube> could achieve
* <amplifier>
* <electronic switch>


Transistor

{wiki}

= Amplification
{synonym}

Main implementations: the same as <electronic switches>: <vacuum tubes> in the past, and <transistors> in the second half of the 20th century.

\Video[https://www.youtube.com/watch?v=4ObzEft2R_g]
{title=How to make an LM386 audio amplifier circuit by #Afrotechmods (2017)}
{description=Builds the circuit on a <breadboard> from minimal components, including one discrete <transistor>. Then plays music from phone through headset cables into a <speaker>.}


Ciro Santilli @cirosantilli 37

 Incoming links: Amplifier