From OC71 to PIC16F18114

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Gordy7

gordy7
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#323899 1-Feb-2026 11:34

A curiosity search on Google:

comparison of physical volume of semiconductor used in an OC71 transistor vs PIC16F18114

An introductory AI result:

The physical volume of semiconductor material in a single 1950s OC71 transistor is roughly 1,000 to 10,000 times larger than the entire silicon die of a modern PIC16F18114 microcontroller, even though the PIC16F18114 contains millions of times more functionality.

Similar comparisons can be made with an OA91 diode and a BC109 transistor

Interesting links as a follow up:

Youtube video on The Construction of the Mullard OC71 Transistor:

https://www.youtube.com/watch?v=fxg6nC2m9L8&t=144s

IEEE Spectrum: The State of the Transistor in 3 Charts (includes transistors in processors)

https://spectrum.ieee.org/transistor-density

Youtube video: How are Microchips Made? Branch Education.

https://www.youtube.com/watch?v=dX9CGRZwD-w&t=1078s

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.

SepticSceptic

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#3457806 1-Feb-2026 22:40

But you can't scrape off the black paint and turn the PIC into a phototransistor ... 😄

You could on an OC71.

I probably have one kicking around somewhere. Together with some AC127, etc.

Might even have some DTL logic chips....

Yeah bit of a hoarder..

Gordy7

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#3457811 1-Feb-2026 23:45

SepticSceptic:

But you can't scrape off the black paint and turn the PIC into a phototransistor ... 😄

You could on an OC71.

I probably have one kicking around somewhere. Together with some AC127, etc.

Might even have some DTL logic chips....

Yeah bit of a hoarder..

Yes... I remember using an OC71 as a photo transistor... using the sun and a mirror on a speaker to an OC71 in a crude audio link...

Still available 😀

I am somewhat in awe with the capabilities of the PIC chips which you can get for about $1.

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.

SepticSceptic

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#3458140 2-Feb-2026 21:48

Yeah, with you on that.

And so readily available for the masses, and now so easy to use.

A couple of decades ago, what is in the PICs and Pi's was a 8031 or 6805 based controller on a circuit board with glue logic and rs232 terminal, and stuff all memory.

Been perusing some old cc-ink mags, I am so pleased we have come a long way to make microprocessors so readily available.

Even at 0.07 cents for a decent but basic 8 bit banger,in small quantities

Technofreak

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#3458144 2-Feb-2026 22:25

I remember playing around with BC 108's and 109's etc as a teenager.I made up my own boards out of old bits of formica drilling a grid pattern of holes to mount the discrete components and soldering the legs together on the bottom side of the board.

You can do so much more today with IC's etc though I don't know it's any more (or less) fun than in yesteryear

Oh how the world has changed

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