4046 PLL model scarcity.

It depends on the circuit constants. You want the total charge flowing through the resistor per cycle to equal that contributed by some safe number T nanoseconds' worth of the phase detector pulling HIGH or LOW. T is something like 10 for HCMOS at 5V, maybe 50-200 for metal gate, depending on the supply voltage. A current source is probably better, but that's getting a bit fancy.

If you have a spectrum analyzer, look at the output with and without the resistor--maybe use a pot for testing purposes. The change in the jitter sidebands is pretty dramatic when you pull just outside the deadband.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

Jim Thompson wrote in news: snipped-for-privacy@4ax.com:

For interesting uses in making electronic music, yes. And perhaps any time a fast cheap oscillator is wanted. IF the VCO is linear... Again, I point out that page I linked to:

I thought about using one that way (until I decided that getting a pitch-based voltage to put into Dieter Doepfer's R2M 'ribbon control' unit was more than enough for me), and that page shows at least two people actually did it. Looks like a mighty useful IC to me... Most of the BIG innovators of VCO's for music making would blush when confronted with specs like those guys came up with using a 4046. Only the VCO's on the big famous modular machines even came close.

Phil Hobbs wrote in news:rZudndP6woK-CDTTnZ2dnUVZ snipped-for-privacy@supernews.com:

Please can you give a hobbyists guide type starting point? I.E. starting resistor value to try, and what pin number on a 4046, to connect to ground? From my perspective, trying to understand the circuit behaviour without that info, or to depend on using a spectrum analyser I haven't got, is entirely putting cart before horse. :)

Jim Thompson wrote in news: snipped-for-privacy@4ax.com:

I just thought it worth mentioning that RM Marston in his books, and the authors of the Art of Electronics, all thought it worth going into so either they thought it was very useful, or at least interesting. To me it is both.

Provided you run the VCO at audio frequencies then for the purposes of testing a realtime spectrum analyser is built into Daqarta and ISTR there is a 30 day free trial period to see if you like it.

I have no connection with the author other than as an occasional user.

Price is also within reach of electronics hobbyists - it uses the sound card to digitise the line input on a PC.

--
Regards,
Martin Brown

At audio I doubt that you'll know it even exists because you loop filter corner will be quite low compared to the device delay time. ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

. snipped-for-privacy@electrooptical.net:

The NXP 74HC9046 doesn't have the dead-zone problem on the digital phase-comparator (PC2) and page 8 of the data sheet spells out the problem with the original 4046, and the solution implelmented on the

74HC9046

The voltage-controlled oscillator isn't wildly attractive, but at least the problems with it are spelled out.

You can buy them in small quantities, but not from Farnell

74HCT9046

4HCT9046APWNXP7585573

-- Bill Sloman, Nijmegen

Those wave forms have noise on the peak of each one! Looks like they took measurements possibly using a 1:1 probe or, that circuit just is crappie!

Jamie

Jamie wrote in news:JXkqq.3431$ snipped-for-privacy@newsfe01.iad:

The kind of 'noise' that a 1 pole passive LPF (RC integrator) ought to fix. Or a simple clipper, given that the amplitide would be cosnatnt with frequency. Given that a synthesiser normally uses a 4 pole LPF I doubt they considered that noise important. Analog synth waveforms vary a LOT more than theirs do, you should see some of the 'sawtooths' out there! What you saw is well behaved in comparison.

Martin Brown wrote in news:Uxhqq.2591$ snipped-for-privacy@newsfe02.iad:

Thanks for the idea, I'll look into that. I deliberately stay with W98 so I might be out of luck but if it runs it might be a keeper.

woK-CDTTnZ2dnUVZ snipped-for-privacy@supernews.com:

ng

, e

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hat

y

Do you have a digital 'scope? They have a so-so spectrum analyzer. As far as phase locked loops, I don't know the 4046. But there are a few different approaches. The AoE is as good a place to start as any. I'm very interested in the use of the 4046 as VCO. At the moment I'm using one to drive a stepped sine thingie. I've been starring at the spec sheet curves wondering if there's a sweet spot somewhere in R/C space. At the moment I've got R=3D20k and C=3D470pF.

George H.

Sure, if you post your loop filter component values and operating frequency. If you have a scope, you can look at the PD2 output and adjust the resistor so that the positive pulse is always at least 100 ns wide. That'll give you a bit of frequency-dependent phase error, but that's usually not a big worry in a lowish-performance PLL.

What happens is that the loop oscillates with a small amplitude around the null, sort of like the temperature in your house as the thermostat kicks on and off.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

Jim Thompson wrote in news: snipped-for-privacy@4ax.com:

Now that I DID understand right on first sight. :) I have to say it's not something I noticed in my design, so far as I know. One quirk I saw was a lock indicator based on the outputs of both comparators failing to indicate lock when the audible output proved there was a lock. I don't know what that means... I considered it might mean that PC2 was basing output on a harmonic. (I'm using PC1 in the loop, so I was never sure what PC2 would be doing at the same time until I considered using it for part of the lock indicator).

Awwwwh! You mean you're not audiophool enough to fret over a few hundred pico-seconds of jitter ?:-)

Most lock detectors don't do anything useful but give marketers something to brag about.

...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

Bill Sloman wrote in news:bdbc6f2e-3be2-4278-b1a4- snipped-for-privacy@s11g2000yqi.googlegroups.com:

Thanks, that's useful to me. I might try one, if the HEF4046B VCO doesn't work well enough. One thing I saw, though not for certain as the graph for linearity at a few hundred KHz covers less than two octaves worth, is that linearity may be better at a few hundred KHz rather than audio frequencies. If the same is true for the HEF4046B I might try a scheme I already considered, using some division in the loop to get HF output from AF input, as I only need the voltage, and can scale and offset later. If this can speed response to bass frequency inputs (something I'm also still uncertain of), then I'd definitely do this.

Phil Hobbs wrote in news: snipped-for-privacy@electrooptical.net:

Thanks. :) LPF is currently 100K with 33nF but there is also a 10K in series with the 33nF. It's at least a year or two since I last worked on that pindecked layout so I can't remember why the hell I did that with the 10K but it seemed to work at the time. Frequencies vary, but currently constrained to those a person whistling can make. (I'd been filtering the input with bandpass from 300Hz to 3KHz at one point, though I may eventually want more to see if this thing can track other musical sources).

I have a 100 MHz scope, so I'll look at that PC2 output. I actually use only PC1 in my loop which may be why I never saw the dead zone thing (except in a silly zombie movie iirc...). I do intend use of PC2 in a lock indicator which has been slightly erratic so if that's due to this problem I'll definitely examine it.

Which pin on the 4046 to ground via the resistor, though? I'm asking the dumb question because the answer should prevent me making any number of stupid mistakes if I fail to grasp what you already told me... I mentioned the VCO output but I am only guessing, no-one told me so far unless I missed something.

A VCO, in itself, is a 1/s function. The filter adds another 1/s, so a zero (your 10K) is needed for loop stability.

...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

Jim Thompson wrote in news: snipped-for-privacy@4ax.com:

Hell no. :) I just lack a certain conceptual proportion when it comes to arcane thingers like PLL's..

About the lock detector, there IS a use for me... If the input goes loud and noisy, the VCO shoots as high as the circuit config will let it. Imagine that in a live performance. >:) I did see that when this happens, the lock indicator can usefully inhibit some later device to prevent output. I tried thinking of other ways to solve this, but the lock indicator did better than anythign I came up with, and very cheaply. It's just not always 100%. It always safely mutes for bad input, but does not always indicate when good input and lock are present. This might be a PC2-and-harmonic thing, or some basic flaw in the indicator circuit.

George Herold wrote in news:d420780a-8348-4cce-a2d4- snipped-for-privacy@s7g2000yqa.googlegroups.com:

Indeed. That, and RM Marston's book on linear IC's got me very interested in the 4046. I got most of my starting points from those two, and a bit of trial and error.

No digital scope, but I think Phil Hobbs' post said I'd be ok with an analog scope, if fast enough. (Mine is, I think, more than I'll need for this).

As far as I can tell, most 4046 VCO's will be a lot more linear with 100K to

1Meg with a supply voltage as high as they'll take safely, but the last thing I am is an authoroty on this...