Who is still using 4000 series CMOS logic?

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rogs

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Jun 23, 2006
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I have a guitarist friend who uses a looper pedal on stage to replay backing tracks.
Works well - but he hates having to press the looper control button twice , just to stop the device.

He approached a technically minded colleague, who told him that an interface to allow a single footswitch press, to both start and stop the unit, was "a simple task for an Arduino".
Problem was this 'simple' interface never materialised.... Always seemed to be stuck at the "just need to sketch a layout and write some simple code" stage....
I'm sure many of us know colleagues who often say that! :)

I thought this simple task was massive overkill for any kind of microcontroller - Arduino, PIC or otherwise - and told him I'd knock up an interface using simple CMOS logic.

(Some notes here of the project results : www.loop.jp137.com ). He uses the 'single switch' version and it works well.

Point is, I was quite surprised to find that many 4000 series CMOS logic ICs are still easily available and quite cheap - even from mainstream suppliers.
There even seem to be quite a lot of good old DIP 'thru-hole' variants still listed!

Why? --- I remember an old Phillips (NXP) data book published in around 1986 'recommending' that 4000 series 'should not be considered for new designs'..... And yet here we are, 35+ years on, with many of the devices still freely available.
Who's using them - they're certainly not being made just for 'stripboard hobbyists' like me.... There's only about 3 of us left :)

So, with the huge uptake in microcontrollers for control system designs, where are these old CMOS chips still being used in large enough quantities to justify ongoing active production - from major manufacturers like Texas for example?

Doesn't seem to make sense?.....
 
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They will keep making them as long as customers keep buying them in decent numbers.

I enjoyed messing with 4000 series CMOS logic back in the 70s. I can imagine them still being the right tool for the job. CMOS process technology has improved dramatically since back then. We can even see CMOS op amps that don't suck, like early ones did.

probably big batches of those silicons were made long ago, only to be sliced and packed (that's cheap to do) at request

Like the CA3080 we ran out of some years ago, there hadn't been a wafer made since the beginning of time

/Jakob E.
I have been outside the walls since leaving last century but Peavey used truckloads of OTAs in their iconic DDT clip limiters (used on almost every amp channel). As I recall we had a house number OTA device graded for input offset voltage to reduce control feed through. I don't know what they would be using these days instead.

JR
 
fwiw CA3080 was a key component in HV (10kV) boards at a company I was at. Around 2003. But obviously we avoided them in the new product under development.
 
An obvious advantage in some instances is the voltage range 3V to 15V. Not everything is based on 3V3 or 5V etc. So they can save stages of voltage/level translation and fault protection.
Eg in the guitar pedal world you probably have a nominally 9V supply. And if it's an unregulated supply coming in it may be several volts above that. So they fit the bill in terms of using that for switching etc.
 
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An obvious advantage in some instances is the voltage range 3V to 15V. Not everything is based on 3V3 or 5V etc. So they can save stages of voltage/level translation and fault protection.
Eg in the guitar pedal world you probably have a nominally 9V supply. And if it's an unregulated supply coming in it may be several volts above that. So the fit the bill in terms of using that for switching etc.
The fact that my little interface was to be be powered from a typical 9V 'stompbox' type power supply was one of the reasons I decided to use 4000 series, rather than 74HC for example
OK, 4000 series might be 'slow' by modern standards, but for applications like mine - and I'm guessing many others? -- speed is not a big deal, so 4000 series is fine.
 
They're still a good answer for fixed-function circuits - timers, sequencing, etc. If you're primarily a manufacturing operation, there's huge benefit in having a circuit which someone designed in the 80's or 90's still work just by soldering the pieces together.

Microcontrollers mean software, and software means development tools, bug tracking, version control, device programming, production test, and of course hiring programmers and explaining to them what you want. Sorry, that's me moaning about my day job...
 

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