Question on zero-crossing circuit

[t.vendredi]

On Fri, 02 May 2014 20:37:47 -0400, Phil Hobbs
<hobbs@electrooptical.net> wrote:

On 5/2/2014 8:33 PM, John Fields wrote:
On Fri, 02 May 2014 12:16:01 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

On Fri, 02 May 2014 02:07:29 -0500, John Fields
jfields@austininstruments.com> wrote:

On Thu, 01 May 2014 21:39:44 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:



Compare that to some of the other dozens-of-parts hairballs
posted here that don't even isolate.

---
Isolation is easy to get, accuracy isn't so easy, and "Hairballs" is
a derogatory term and has no place in an emotion-free discussion,
especially from an engineer who demeans emotionality in technical
discussions.

"Hairball" is an accepted technical term for an overly complex design,
often asynchronous logic, that has hazards.

---
I didn't just fall off the turnip truck, and I've never seen it used
in other than a derogatory way.

Do you have a link to verify your claim?

http://tinyurl.com/jvlo89z

Cheers

Phil Hobbs

So sprechen Sie die sychophant

 

[Phil Hobbs]

On 5/2/2014 9:06 PM, t.vendredi wrote:

On Fri, 02 May 2014 20:37:47 -0400, Phil Hobbs
hobbs@electrooptical.net> wrote:

On 5/2/2014 8:33 PM, John Fields wrote:
On Fri, 02 May 2014 12:16:01 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

On Fri, 02 May 2014 02:07:29 -0500, John Fields
jfields@austininstruments.com> wrote:

On Thu, 01 May 2014 21:39:44 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:



Compare that to some of the other dozens-of-parts hairballs
posted here that don't even isolate.

---
Isolation is easy to get, accuracy isn't so easy, and "Hairballs" is
a derogatory term and has no place in an emotion-free discussion,
especially from an engineer who demeans emotionality in technical
discussions.

"Hairball" is an accepted technical term for an overly complex design,
often asynchronous logic, that has hazards.

---
I didn't just fall off the turnip truck, and I've never seen it used
in other than a derogatory way.

Do you have a link to verify your claim?

http://tinyurl.com/jvlo89z

Cheers

Phil Hobbs


So spricht der Sykophant

Liebe herr unbekannt: I gather you don't have any friends. John is one
of mine. He doesn't need my help to defend himself in this company, of
course, but most of the time we're on the same page.

What's German for "mutual regard"?

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

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

 

[Phil Hobbs]

On 5/2/2014 9:08 PM, t.vendredi wrote:

On Fri, 02 May 2014 20:37:47 -0400, Phil Hobbs
hobbs@electrooptical.net> wrote:

On 5/2/2014 8:33 PM, John Fields wrote:
On Fri, 02 May 2014 12:16:01 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

On Fri, 02 May 2014 02:07:29 -0500, John Fields
jfields@austininstruments.com> wrote:

On Thu, 01 May 2014 21:39:44 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:



Compare that to some of the other dozens-of-parts hairballs
posted here that don't even isolate.

---
Isolation is easy to get, accuracy isn't so easy, and "Hairballs" is
a derogatory term and has no place in an emotion-free discussion,
especially from an engineer who demeans emotionality in technical
discussions.

"Hairball" is an accepted technical term for an overly complex design,
often asynchronous logic, that has hazards.

---
I didn't just fall off the turnip truck, and I've never seen it used
in other than a derogatory way.

Do you have a link to verify your claim?

http://tinyurl.com/jvlo89z

Cheers

Phil Hobbs

So sprechen Sie die sychophant

Dear Mr. Friday: You seem to be repeating yourself. Are you JT's
sockpuppet or what?


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

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

 

[John Fields]

On Fri, 02 May 2014 20:37:47 -0400, Phil Hobbs
<hobbs@electrooptical.net> wrote:

On 5/2/2014 8:33 PM, John Fields wrote:
On Fri, 02 May 2014 12:16:01 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

On Fri, 02 May 2014 02:07:29 -0500, John Fields
jfields@austininstruments.com> wrote:

On Thu, 01 May 2014 21:39:44 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:



Compare that to some of the other dozens-of-parts hairballs
posted here that don't even isolate.

---
Isolation is easy to get, accuracy isn't so easy, and "Hairballs" is
a derogatory term and has no place in an emotion-free discussion,
especially from an engineer who demeans emotionality in technical
discussions.

"Hairball" is an accepted technical term for an overly complex design,
often asynchronous logic, that has hazards.

---
I didn't just fall off the turnip truck, and I've never seen it used
in other than a derogatory way.

Do you have a link to verify your claim?

http://tinyurl.com/jvlo89z

Cheers

Phil Hobbs

---
The noun, not the proper noun.

Close, but no seegar.

jfields

 

[Douglas Beeson]

On Fri, 02 May 2014 09:24:57 -0500
John Fields <jfields@austininstruments.com> wrote:

On Fri, 2 May 2014 09:49:11 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

.
.
.

My interest in ZCD circuits stems from a need to limit "clicks" when an amplified,
audio-like signal is gated. I am looking at 13.8 Vp-p and 0.1-20kHz frequency.
I want to trigger a uController with the leading or trailing edge of a comparator
pulse so that the turnon or shutoff occurs only when voltage is near zero.

.
.
.

doug

---
From your description it sounds like you have an AC signal which you
want to switch into a load, but only after the switch is turned on
and then close to when the next AC zero crossing occurs.

Once that happens and the AC is feeding the load, you want the
switch to stay ON for some time and then, when it's switched OFF,
disconnect the AC from the load close to when the next AC zero
crossing occurs.

Is that what you're looking for?

John Fields

Yup, that's exactly right. I have built a non-zero-cross detecting version of the circuit and it switches fine, but damn! it clicks on both closing and opening the MOSFET switch. I haven't yet measured the minimal voltage or current -- the load is a 6 ohm woofer -- at which the click is audible, but I am assuming somewhere in the 10mA-100mA range. My idea is to use the PIC's edge detect feature to trigger an interrupt when the zero cross has occurred, and open or close the switch at that point if necessary.



--
Douglas Beeson <c.difficile@gmail.com>

 

[John Larkin]

On Fri, 02 May 2014 19:33:38 -0500, John Fields <jfields@austininstruments.com>
wrote:

On Fri, 02 May 2014 12:16:01 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

On Fri, 02 May 2014 02:07:29 -0500, John Fields
jfields@austininstruments.com> wrote:

On Thu, 01 May 2014 21:39:44 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:



Compare that to some of the other dozens-of-parts hairballs
posted here that don't even isolate.

---
Isolation is easy to get, accuracy isn't so easy, and "Hairballs" is
a derogatory term and has no place in an emotion-free discussion,
especially from an engineer who demeans emotionality in technical
discussions.

"Hairball" is an accepted technical term for an overly complex design,
often asynchronous logic, that has hazards.

---
I didn't just fall off the turnip truck, and I've never seen it used
in other than a derogatory way.

Of course it's derogatory. It means "bad circuit."

If it's *your* bad circuit, you might take it personally.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation

 

[John Larkin]

On Fri, 02 May 2014 18:27:27 -0500, John Fields <jfields@austininstruments.com>
wrote:

On Fri, 02 May 2014 14:58:51 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

On Fri, 02 May 2014 12:51:02 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Fri, 02 May 2014 12:16:01 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

On Fri, 02 May 2014 02:07:29 -0500, John Fields
jfields@austininstruments.com> wrote:

On Thu, 01 May 2014 21:39:44 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Fri, 02 May 2014 08:04:26 +1000, "David Eather" <eather@tpg.com.au> wrote:

[snip]
---

It's perfectly feasible. The reason to keep the current down isn't to protect
the LEDs, it's to keep the power dissipation down in the input resistors.

One dual opto, two resistors. Or even one resistor. Output is a clean, isolated,
r-r square wave.

---
Not from #3, since it's essentially a De Morgan equivalent "OR" with
an output which will be a narrow positive-going pulse which will
straddle the zero-crossings.
---

Compare that to some of the other dozens-of-parts hairballs
posted here that don't even isolate.

---
Isolation is easy to get, accuracy isn't so easy, and "Hairballs" is
a derogatory term and has no place in an emotion-free discussion,
especially from an engineer who demeans emotionality in technical
discussions.

"Hairball" is an accepted technical term for an overly complex design,
often asynchronous logic, that has hazards.

You didn't answer John Fields question... you dodged... as usual.

...Jim Thompson

He seems to be pointing out that some of my circuits output a square
wave and some make a pulse at each zero crossing. I can't deny that.

---
The text and links to graphics you snipped clearly indicated that
your #3 put out a square wave when, in fact, as you're now
backhandedly admitting, it puts out a narrow pulse which straddles
the zero crossings.

More importantly, though, you snipped the request for information as
to the part number of a dual opto with tight enough CTR matching to
achieve what _you_ consider to be an accurate enough zero-crossing
capture for the discussion at hand, and the request for information
as to the effect of the reactance of a phase-lead cap on the CTR
matching of the opto pair.

Typical Larkinese move: Don't answer any compromising questions;
just pretend they never existed and pretty soon everybody will
forget about it, saving you some face.
---

I can't see what De Morgan's Theorem has to do with anything here,
other than some words to throw around.

---
Then you don't understand De Morgan's theorem as it relates to your
circuit.

Or, maybe, not at all...

OK, explain it.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation

 

[John Fields]

On Fri, 02 May 2014 19:03:45 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Fri, 02 May 2014 18:27:27 -0500, John Fields <jfields@austininstruments.com
wrote:

On Fri, 02 May 2014 14:58:51 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

On Fri, 02 May 2014 12:51:02 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Fri, 02 May 2014 12:16:01 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

On Fri, 02 May 2014 02:07:29 -0500, John Fields
jfields@austininstruments.com> wrote:

On Thu, 01 May 2014 21:39:44 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Fri, 02 May 2014 08:04:26 +1000, "David Eather" <eather@tpg.com.au> wrote:

[snip]
---

It's perfectly feasible. The reason to keep the current down isn't to protect
the LEDs, it's to keep the power dissipation down in the input resistors.

One dual opto, two resistors. Or even one resistor. Output is a clean, isolated,
r-r square wave.

---
Not from #3, since it's essentially a De Morgan equivalent "OR" with
an output which will be a narrow positive-going pulse which will
straddle the zero-crossings.
---

Compare that to some of the other dozens-of-parts hairballs
posted here that don't even isolate.

---
Isolation is easy to get, accuracy isn't so easy, and "Hairballs" is
a derogatory term and has no place in an emotion-free discussion,
especially from an engineer who demeans emotionality in technical
discussions.

"Hairball" is an accepted technical term for an overly complex design,
often asynchronous logic, that has hazards.

You didn't answer John Fields question... you dodged... as usual.

...Jim Thompson

He seems to be pointing out that some of my circuits output a square
wave and some make a pulse at each zero crossing. I can't deny that.

---
The text and links to graphics you snipped clearly indicated that
your #3 put out a square wave when, in fact, as you're now
backhandedly admitting, it puts out a narrow pulse which straddles
the zero crossings.

More importantly, though, you snipped the request for information as
to the part number of a dual opto with tight enough CTR matching to
achieve what _you_ consider to be an accurate enough zero-crossing
capture for the discussion at hand, and the request for information
as to the effect of the reactance of a phase-lead cap on the CTR
matching of the opto pair.

Typical Larkinese move: Don't answer any compromising questions;
just pretend they never existed and pretty soon everybody will
forget about it, saving you some face.
---

I can't see what De Morgan's Theorem has to do with anything here,
other than some words to throw around.

---
Then you don't understand De Morgan's theorem as it relates to your
circuit.

Or, maybe, not at all...

OK, explain it.

---
Rather than thrash around with you in the mud, go to "ENGINEERING"
at:

http://en.wikipedia.org/wiki/De_Morgan's_laws

and work it out for yourself.


jfields

 

[John Fields]

On Fri, 02 May 2014 19:05:55 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Fri, 02 May 2014 19:33:38 -0500, John Fields <jfields@austininstruments.com
wrote:

On Fri, 02 May 2014 12:16:01 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

On Fri, 02 May 2014 02:07:29 -0500, John Fields
jfields@austininstruments.com> wrote:

On Thu, 01 May 2014 21:39:44 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:



Compare that to some of the other dozens-of-parts hairballs
posted here that don't even isolate.

---
Isolation is easy to get, accuracy isn't so easy, and "Hairballs" is
a derogatory term and has no place in an emotion-free discussion,
especially from an engineer who demeans emotionality in technical
discussions.

"Hairball" is an accepted technical term for an overly complex design,
often asynchronous logic, that has hazards.

---
I didn't just fall off the turnip truck, and I've never seen it used
in other than a derogatory way.

Of course it's derogatory. It means "bad circuit."

---
It means much more than that, as you well know:

http://www.merriam-webster.com/dictionary/derogatory

and, by your own admission, such inflammatory disrespect has no
place in an objective discussion.
---

>If it's *your* bad circuit, you might take it personally.

---
If it's my bad circuit and the reason(s) for its badness are
enumerated in a rational way, then that constructive criticism will
be gratefully received and acknowledged.

If, on the other hand, insult instead of constructive criticism is
the intent of the critic, then of course I'll take it personally.

 

[John Larkin]

On Sat, 03 May 2014 05:10:02 -0500, John Fields <jfields@austininstruments.com>
wrote:

On Fri, 02 May 2014 19:03:45 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Fri, 02 May 2014 18:27:27 -0500, John Fields <jfields@austininstruments.com
wrote:

On Fri, 02 May 2014 14:58:51 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

On Fri, 02 May 2014 12:51:02 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Fri, 02 May 2014 12:16:01 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

On Fri, 02 May 2014 02:07:29 -0500, John Fields
jfields@austininstruments.com> wrote:

On Thu, 01 May 2014 21:39:44 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Fri, 02 May 2014 08:04:26 +1000, "David Eather" <eather@tpg.com.au> wrote:

[snip]
---

It's perfectly feasible. The reason to keep the current down isn't to protect
the LEDs, it's to keep the power dissipation down in the input resistors.

One dual opto, two resistors. Or even one resistor. Output is a clean, isolated,
r-r square wave.

---
Not from #3, since it's essentially a De Morgan equivalent "OR" with
an output which will be a narrow positive-going pulse which will
straddle the zero-crossings.
---

Compare that to some of the other dozens-of-parts hairballs
posted here that don't even isolate.

---
Isolation is easy to get, accuracy isn't so easy, and "Hairballs" is
a derogatory term and has no place in an emotion-free discussion,
especially from an engineer who demeans emotionality in technical
discussions.

"Hairball" is an accepted technical term for an overly complex design,
often asynchronous logic, that has hazards.

You didn't answer John Fields question... you dodged... as usual.

...Jim Thompson

He seems to be pointing out that some of my circuits output a square
wave and some make a pulse at each zero crossing. I can't deny that.

---
The text and links to graphics you snipped clearly indicated that
your #3 put out a square wave when, in fact, as you're now
backhandedly admitting, it puts out a narrow pulse which straddles
the zero crossings.

More importantly, though, you snipped the request for information as
to the part number of a dual opto with tight enough CTR matching to
achieve what _you_ consider to be an accurate enough zero-crossing
capture for the discussion at hand, and the request for information
as to the effect of the reactance of a phase-lead cap on the CTR
matching of the opto pair.

Typical Larkinese move: Don't answer any compromising questions;
just pretend they never existed and pretty soon everybody will
forget about it, saving you some face.
---

I can't see what De Morgan's Theorem has to do with anything here,
other than some words to throw around.

---
Then you don't understand De Morgan's theorem as it relates to your
circuit.

Or, maybe, not at all...

OK, explain it.

---
Rather than thrash around with you in the mud, go to "ENGINEERING"
at:

http://en.wikipedia.org/wiki/De_Morgan's_laws

and work it out for yourself.


jfields

Word salad again.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation

 

[Douglas Beeson]

On Fri, 02 May 2014 08:36:23 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Fri, 02 May 2014 08:18:11 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Fri, 2 May 2014 09:51:26 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

On Thu, 1 May 2014 17:01:49 -0400
WangoTango <Asgard24@mindspring.com> wrote:

In article <20140501081051.f2341ef5d60270d968a0bc7b@gmail.com>,
c.difficile@gmail.com says...
Hi all,

I did a search the other day on zero crossing detector circuits and came across this nice one by Jim Thompson:

http://www.analog-innovations.com/SED/Zero_Crossing.pdf

I think I have figured out how it works, except for capacitor C1. What does it do?

Thanks!


Are you just looking at it to understand it, or are you looking for a
Zero Crossing Detector to actually use?

I have one that I have used for many moons that is a heck of a lot less
convoluted that this one and has proven to be quite reliable.


Thanks for your reply. I do have an actual need, but only at lower voltages (13.8 V max). It has to cutoff closer to zero than the 1 diode drop of Jim's circuit, though. I'm interested in seeing your design if you're willing to post it.

-doug

Straddle zero, or just one side of zero? What voltage level do you
want?

...Jim Thompson

Power supplies, signal levels, AC or DC-coupled?

Signal level (0-13.8 V) AC-coupled. The circuit will be battery powered, so single supply. The basic idea is to use a ZCD to trigger a uController that is handling the gating function. I want avoid "clicks" in the woofer when the audio is cut or reenabled. I'm not sure yet at what voltage level the clicking will cease, but some basic tests with a 9V battery, a pot and a speaker tell me that it doesn't take much to make a woofer go 'pop', probably < 1 mV.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)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.

--
Douglas Beeson <c.difficile@gmail.com>

 

[Jim Thompson]

On Sat, 3 May 2014 11:11:38 -0400, Douglas Beeson
<c.difficile@gmail.com> wrote:

On Fri, 02 May 2014 08:36:23 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Fri, 02 May 2014 08:18:11 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Fri, 2 May 2014 09:51:26 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

On Thu, 1 May 2014 17:01:49 -0400
WangoTango <Asgard24@mindspring.com> wrote:

In article <20140501081051.f2341ef5d60270d968a0bc7b@gmail.com>,
c.difficile@gmail.com says...
Hi all,

I did a search the other day on zero crossing detector circuits and came across this nice one by Jim Thompson:

http://www.analog-innovations.com/SED/Zero_Crossing.pdf

I think I have figured out how it works, except for capacitor C1. What does it do?

Thanks!


Are you just looking at it to understand it, or are you looking for a
Zero Crossing Detector to actually use?

I have one that I have used for many moons that is a heck of a lot less
convoluted that this one and has proven to be quite reliable.


Thanks for your reply. I do have an actual need, but only at lower voltages (13.8 V max). It has to cutoff closer to zero than the 1 diode drop of Jim's circuit, though. I'm interested in seeing your design if you're willing to post it.

-doug

Straddle zero, or just one side of zero? What voltage level do you
want?

...Jim Thompson

Power supplies, signal levels, AC or DC-coupled?


Signal level (0-13.8 V) AC-coupled. The circuit will be battery powered, so single supply. The basic idea is to use a ZCD to trigger a uController that is handling the gating function. I want avoid "clicks" in the woofer when the audio is cut or reenabled. I'm not sure yet at what voltage level the clicking will cease, but some basic tests with a 9V battery, a pot and a speaker tell me that it doesn't take much to make a woofer go 'pop', probably < 1 mV.


...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)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.

I the early '60's I used a _mechanically_delayed_ relay that connected
speakers after the amplifier bias had settled. My situation was not a
"pop", it was more like a "cannon shot" ;-)

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)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.

 

[John Fields]

On Sat, 03 May 2014 07:34:37 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 03 May 2014 05:10:02 -0500, John Fields <jfields@austininstruments.com
wrote:

On Fri, 02 May 2014 19:03:45 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Fri, 02 May 2014 18:27:27 -0500, John Fields <jfields@austininstruments.com
wrote:

On Fri, 02 May 2014 14:58:51 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

On Fri, 02 May 2014 12:51:02 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Fri, 02 May 2014 12:16:01 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

On Fri, 02 May 2014 02:07:29 -0500, John Fields
jfields@austininstruments.com> wrote:

On Thu, 01 May 2014 21:39:44 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Fri, 02 May 2014 08:04:26 +1000, "David Eather" <eather@tpg.com.au> wrote:

[snip]
---

It's perfectly feasible. The reason to keep the current down isn't to protect
the LEDs, it's to keep the power dissipation down in the input resistors.

One dual opto, two resistors. Or even one resistor. Output is a clean, isolated,
r-r square wave.

---
Not from #3, since it's essentially a De Morgan equivalent "OR" with
an output which will be a narrow positive-going pulse which will
straddle the zero-crossings.
---

Compare that to some of the other dozens-of-parts hairballs
posted here that don't even isolate.

---
Isolation is easy to get, accuracy isn't so easy, and "Hairballs" is
a derogatory term and has no place in an emotion-free discussion,
especially from an engineer who demeans emotionality in technical
discussions.

"Hairball" is an accepted technical term for an overly complex design,
often asynchronous logic, that has hazards.

You didn't answer John Fields question... you dodged... as usual.

...Jim Thompson

He seems to be pointing out that some of my circuits output a square
wave and some make a pulse at each zero crossing. I can't deny that.

---
The text and links to graphics you snipped clearly indicated that
your #3 put out a square wave when, in fact, as you're now
backhandedly admitting, it puts out a narrow pulse which straddles
the zero crossings.

More importantly, though, you snipped the request for information as
to the part number of a dual opto with tight enough CTR matching to
achieve what _you_ consider to be an accurate enough zero-crossing
capture for the discussion at hand, and the request for information
as to the effect of the reactance of a phase-lead cap on the CTR
matching of the opto pair.

Typical Larkinese move: Don't answer any compromising questions;
just pretend they never existed and pretty soon everybody will
forget about it, saving you some face.
---

I can't see what De Morgan's Theorem has to do with anything here,
other than some words to throw around.

---
Then you don't understand De Morgan's theorem as it relates to your
circuit.

Or, maybe, not at all...

OK, explain it.

---
Rather than thrash around with you in the mud, go to "ENGINEERING"
at:

http://en.wikipedia.org/wiki/De_Morgan's_laws

and work it out for yourself.


jfields

Word salad again.

---
Seems perfectly clear to me, but then I'm not you, am I?

BTW, are you _ever_ going to come across with the OPTO and the zero
crossing window spec's?

 

[John Fields]

On Fri, 2 May 2014 22:21:40 -0400, Douglas Beeson
<c.difficile@gmail.com> wrote:

On Fri, 02 May 2014 09:24:57 -0500
John Fields <jfields@austininstruments.com> wrote:

On Fri, 2 May 2014 09:49:11 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

.
.
.

My interest in ZCD circuits stems from a need to limit "clicks" when an amplified,
audio-like signal is gated. I am looking at 13.8 Vp-p and 0.1-20kHz frequency.
I want to trigger a uController with the leading or trailing edge of a comparator
pulse so that the turnon or shutoff occurs only when voltage is near zero.

.
.
.

doug

---
From your description it sounds like you have an AC signal which you
want to switch into a load, but only after the switch is turned on
and then close to when the next AC zero crossing occurs.

Once that happens and the AC is feeding the load, you want the
switch to stay ON for some time and then, when it's switched OFF,
disconnect the AC from the load close to when the next AC zero
crossing occurs.

Is that what you're looking for?

John Fields

Yup, that's exactly right. I have built a non-zero-cross detecting version of the circuit and it switches fine, but damn! it clicks on both closing and opening the MOSFET switch. I haven't yet measured the minimal voltage or current -- the load is a 6 ohm woofer -- at which the click is audible, but I am assuming somewhere in the 10mA-100mA range. My idea is to use the PIC's edge detect feature to trigger an interrupt when the zero cross has occurred, and open or close the switch at that point if necessary.

---
I've posted a circuit concept you can simulate on
alt.binaries.schematics.electronic:

news:7jhcm9tch9suq10a83lg73a2ccciv804dn@4ax.com

Let me know if you need a circuit description and I'll be happy to
post it.

John Fields

 

[Tom Del Rosso]

Jim Thompson wrote:

The impedance of C1 is ~12K @60Hz, limiting the recirculating current.
Transformers are expensive, and bulky.

Doesn't R4/C5 cause a delay in the time domain?


--

Reply in group, but if emailing, add a zero and remove the last word.

 

[John Larkin]

On Fri, 2 May 2014 07:05:28 -0500, "Rick" <rike22@bellsouth.net> wrote:

"Wayne Chirnside" <w.faux@doentexist.com> wrote in message
news:WIE8v.3672482$kl4.3059748@fx10.iad...
On Thu, 01 May 2014 08:10:51 -0400, Douglas Beeson wrote:

Hi all,

I did a search the other day on zero crossing detector circuits and came
across this nice one by Jim Thompson:

http://www.analog-innovations.com/SED/Zero_Crossing.pdf

I think I have figured out how it works, except for capacitor C1. What
does it do?

Thanks!

Provides filtered smoothed DC to the comparators

http://www.fairchildsemi.com/pf/MI/MID400.html
I have used this with good results.

Cool, a photon-based OR gate.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation

 

[Jim Thompson]

On Sun, 4 May 2014 13:47:14 -0400, "Tom Del Rosso"
<td_03@verizon.net.invalid> wrote:

Jim Thompson wrote:

The impedance of C1 is ~12K @60Hz, limiting the recirculating current.
Transformers are expensive, and bulky.

Doesn't R4/C5 cause a delay in the time domain?

Somewhere around 0.6°? It's there just to cleanse noise.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)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]

On Sat, 3 May 2014 11:11:38 -0400, Douglas Beeson
<c.difficile@gmail.com> wrote:

On Fri, 02 May 2014 08:36:23 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

[snip]

Power supplies, signal levels, AC or DC-coupled?


Signal level (0-13.8 V) AC-coupled. The circuit will be battery powered, so single supply. The basic idea is to use a ZCD to trigger a uController that is handling the gating function. I want avoid "clicks" in the woofer when the audio is cut or reenabled. I'm not sure yet at what voltage level the clicking will cease, but some basic tests with a 9V battery, a pot and a speaker tell me that it doesn't take much to make a woofer go 'pop', probably < 1 mV.


...Jim Thompson

Probably your best bet, then, is to amplify your signal, but clamped.
then run thru the zero cross, as in...

<http://www.analog-innovations.com/SED/Zero_Crossing_for_Beeson.pdf>

But that presents a double-edged sword, you get some phase shift.

I don't know what resolution you really need, or how exotic you really
want to get. I once built a circuit that delayed audio so that I
could detect a "pop" on the un-delayed signal then have time to stop a
track and hold to remove the "pop" ;-)

Caution do not take an input to an LM339 below negative rail without a
current-limiting resistor... otherwise the Earth will flip poles and
Al Gore will run again for President >:-}

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)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.