Author Topic: Self-destructing 14-pin DIP  (Read 5209 times)

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Offline MK14

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Re: Self-destructing 14-pin DIP
« Reply #25 on: October 15, 2018, 09:29:01 am »
You certainly can get CD4000UB to operate in "linear" mode.

You can, but the article (Nuts&Volts, link in earlier post of mine) seems to indicate, that they are less useful in analogue applications, than some of the older types. Because they still have the improvements (minus the buffering), which makes them better for digital purposes, but less so, if you want to use them in a linear fashion.
Which reduces the available gain, and hence they are potentially less useful.
Although Bob Pease, if he was still around, might disagree, and indicate improvements in other respects, despite the reduced gain.
 

Offline wraper

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Re: Self-destructing 14-pin DIP
« Reply #26 on: October 15, 2018, 01:08:48 pm »
You certainly can get CD4000UB to operate in "linear" mode.

You can, but the article (Nuts&Volts, link in earlier post of mine) seems to indicate, that they are less useful in analogue applications, than some of the older types. Because they still have the improvements (minus the buffering), which makes them better for digital purposes, but less so, if you want to use them in a linear fashion.
Which reduces the available gain, and hence they are potentially less useful.
Although Bob Pease, if he was still around, might disagree, and indicate improvements in other respects, despite the reduced gain.
There was no mention if they are better or worse for analog application.
 

Offline MK14

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Re: Self-destructing 14-pin DIP
« Reply #27 on: October 15, 2018, 01:23:36 pm »
You certainly can get CD4000UB to operate in "linear" mode.

You can, but the article (Nuts&Volts, link in earlier post of mine) seems to indicate, that they are less useful in analogue applications, than some of the older types. Because they still have the improvements (minus the buffering), which makes them better for digital purposes, but less so, if you want to use them in a linear fashion.
Which reduces the available gain, and hence they are potentially less useful.
Although Bob Pease, if he was still around, might disagree, and indicate improvements in other respects, despite the reduced gain.
There was no mention if they are better or worse for analog application.

Yes there does seem to be, but I could easily be wrong. But I think we should stop discussing it.

I remember from long ago, that the older/original chips were recommended for linear stuff, but the newer/later ones were not. I just can't remember the exact details, such as if it was 4000, 4000A, 4000B, unbuffered, buffered etc etc.

The linked to document, seems to me, with a quick look, to suggest some reasons why the analogue capabilities of the 4000 series, worsens/diminishes, as it gets more modern and improves, its digital abilities.

Anyway, I fully accept that I could be wrong, as I have only quickly read through the document, and can't clearly remember the details from many decades ago.

If you are REALLY concerned (I am, and might experiment in the future), it is probably best to just try experimenting with analogue circuits, using the 4000/A/B/UA/UB etc chips, rather than getting into long arguments on forums about it.

I find it a neat concept, because it is sort of a one input pin, one output pin, op-amp like solution.

Real op-amps are so cheap and available these days, there is little point in trying to use 4000 series devices (which are somewhat obsolete (or heading that way) as well). unless very interested in electronics and/or vintage stuff.

I wanted to build a radio using the CMOS 4000 inverters, at the time (many decades ago), but never actually did it. So, I guess it is part of my long electronics todo wish list.
« Last Edit: October 15, 2018, 01:27:41 pm by MK14 »
 

Offline wraper

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Re: Self-destructing 14-pin DIP
« Reply #28 on: October 15, 2018, 01:26:43 pm »
Yes there is. But I think we should stop discussing it.
Excuse me, but I don't see how this could count as such:
Quote
One disadvantage of the B-series is that its propagation delays are larger than those of the old A-series. To counter this problem, a few new-generation devices are produced in an ‘unbuffered’ format (denoted by a ‘UB’ suffix), but incorporate all the other improvements of the B-series.

Typically, UB inverters have an AC gain of 23 dB at 10 volts, and are useful in several analog applications. Note that the bandwidth and propagation delays of a CMOS device vary with supply voltage and with capacitive output loading. Figure 10 lists the typical propagation delays of both UB and B-series inverters when used with supply values of 5V, 10V, and 15V when driving a 50 pF load.
 

Offline MK14

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Re: Self-destructing 14-pin DIP
« Reply #29 on: October 15, 2018, 01:32:50 pm »
I can probably find the article, I am trying to remember, from probably the 1970s online (many of the older articles get scanned into PDFs and can be found with some, possibly hard work). Which explains why the early 4000 series are good for analogue stuff, but the later ones are not.

It is possible that the 4000UB devices you are referring to, did NOT exist, at the time of the rather ancient article(s), I am thinking of. So, it could be that the 4000UB devices, are better, than some of the other 4000 series devices. But the article(s), I was thinking of, did not cover the 4000UB, as it did not exist then.

I am interested in digging up the old articles, anyway. I will have a look and come back to this thread, if I come across them.
 

Offline Zero999

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Re: Self-destructing 14-pin DIP
« Reply #30 on: October 15, 2018, 04:15:41 pm »
The buffered chips will probably oscillate, if used in a low gain application because they're actually three gates in series, which not only have a high gain, but lots of phase shift. Connecting the input to the output, will make a ring oscillator, unless the feedback node is connected to 0V with a low impedance, compared to the feedback resistor, at AC.
 
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Offline MK14

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Re: Self-destructing 14-pin DIP
« Reply #31 on: October 15, 2018, 04:41:38 pm »
Excuse me, but I don't see how this could count as such:

With extensive research, and while having much fun and bringing back fond, past memories while doing it. I managed to find one tiny paragraph, explaining some of what I was trying to properly remember.

Summary:
It DOES really need to be the ORIGINAL 4000 series, i.e. No A or B types. The 4000UB type isn't mentioned for that year, as far as I can tell, so it may not have been around then, or I didn't look hard enough.

The explanation, is because the original 4000 series, had just a single transistor complementary pair. Which, hence allowed reliable/stable analogue/linear circuits to be constructed.

Coincidentally, the original 4000 series, did not have the ESD protection, which was what I was somewhat remembering, in relation to this issue.

It seems to be saying that later types (4000A and if available in the applicable type then, 4000B), are too unstable, to use in (at least the circuit it gives), due to the extra transistors. Which cause instability.

There were other information articles/projects/examples, explaining about it. But they would take considerably longer to find.

Please refer to bottom of page 26, in the following link.

Source:
https://www.americanradiohistory.com/Archive-Electronics-Today/ETI-Circuits-No-2-1978.pdf

I don't really definitively know if the (presumably) later 4000UB series, would be suitable, in those circuits. So you could be right (or not).

Does it really matter, since a modern, low cost, much better in most measurable ways, op-amp, would probably make a much better solution.

The original 4000 series, are probably getting increasingly harder to get, these days. I seem to remember, them being very difficult to get, even forty years ago (at least in the UK), as they were rapidly replaced by the 4000A and 4000B devices.
 

Offline MK14

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Re: Self-destructing 14-pin DIP
« Reply #32 on: October 15, 2018, 04:42:47 pm »
The buffered chips will probably oscillate, if used in a low gain application because they're actually three gates in series, which not only have a high gain, but lots of phase shift. Connecting the input to the output, will make a ring oscillator, unless the feedback node is connected to 0V with a low impedance, compared to the feedback resistor, at AC.

Probably exactly right!

That seems to be similar to what the mini-article is saying (implying/hinting etc), linked to above. I.e. Instability.
 

Offline IanMacdonald

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Re: Self-destructing 14-pin DIP
« Reply #33 on: October 15, 2018, 04:48:14 pm »
The supply voltage is important for good analog performance. Too low and you will have a dead band in which neither FET conducts. Too high and the conductance will overlap causing a high quiescent current.
 
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Offline MK14

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Re: Self-destructing 14-pin DIP
« Reply #34 on: October 15, 2018, 05:09:26 pm »
The supply voltage is important for good analog performance. Too low and you will have a dead band in which neither FET conducts. Too high and the conductance will overlap causing a high quiescent current.

That makes a lot of sense. I think it is similar to what Bob Pease's (in the article he wrote, details earlier in this thread) concerns over the excessive sensitivity to changes in supply voltage, which these types of circuit, has.

Because, with normal CMOS (even the latest modern stuff), and when using it digitally. You are usually/often warned, to NOT allow any inputs to float at around half of the supply voltage and/or have too slow a signal transition, from low to high, or high to low (and hence it would be at the half way voltage for some of the time).
Because it can cause excessive current/power consumption. Essentially because it can cause the top and bottom, MOSFETs to conduct at the same time (shoot-through), hence the excessive current/power use.

Hence the "Too high and the conductance will overlap causing a high quiescent current", part of your explanation.

So, by keeping the supply voltage low enough (but while still being above the minimum supply voltage you just mentioned and probably more to safely be in the type of "linear mode" we are discussing, so the MOSFET gates get enough voltage to begin to turn on etc), it avoids/minimizes the possible excessive current consumption.
« Last Edit: October 15, 2018, 05:18:26 pm by MK14 »
 

Offline MK14

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Re: Self-destructing 14-pin DIP
« Reply #35 on: October 15, 2018, 05:54:57 pm »
Just in case anyone is interested.
The magazines I was aiming for, was the UK edition of ETI (Electronics Today International), around the 1975 to 1978 time period (narrowed down by my estimates, of when I read the article(s) ). I encountered other electronics magazines, but feel ETI makes the most sense.

My gut feeling was before 1975 (4000 CMOS seems not so available in the UK, to hobbyists/me of that era) would be too early, and after the end of 1978, things (as regards 4000 CMOS, linear/analogue use), had moved on too much (i.e. it would probably be mostly/always op-amps and stuff, then, in magazine circuits).
But it could have been outside of those years.

A large number of those magazines (in PDF form), are available here:
https://www.americanradiohistory.com/ETI_Magazine.htm
« Last Edit: October 15, 2018, 06:02:50 pm by MK14 »
 


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