Zero Cross Detection circuit for review

[Douglas Beeson]

Hello all,

I'm back again with an audio zero-cross detection circuit that I have designed based on valuable feedback from some of you (notably Jim Thompson and John Fields). I am trying to gate an audio signal while avoiding clicks as it switches on and off.

I'm submitting the LTSpice file here for your comments and also to ask why one thing does not seem to be working as intended:

The output from the two LM339 comparators seems to go all to hell once some part of input frequency goes over 1000 Hz or so. It all works fine at lower frequencies, and if there is just one comparator instead of two (but I need two to handle zeroes at rising and falling). I haven't built the actual circuit in real parts (lab is a bit of a mess at the moment), but LTSpice is usually far wiser than me, so I must have a flaw in the logic somewhere!

Thanks for your comments and help.

doug beeson

PS: Links for the referenced libraries are here:
https://dl.dropboxusercontent.com/u/2156133/lm324.lib
https://dl.dropboxusercontent.com/u/2156133/LM339.lib
https://dl.dropboxusercontent.com/u/2156133/PMV31XN.lib
https://dl.dropboxusercontent.com/u/2156133/PMV33UPE.lib


Version 4
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SYMBOL Comparators/LM339 320 816 R0
SYMATTR InstName U1
SYMBOL voltage -704 1728 R0
SYMATTR InstName V1
SYMATTR Value SINE(0 7 2 0.1 0 0 8)
SYMBOL voltage 0 272 R0
SYMATTR InstName V2
SYMATTR Value -9
SYMBOL voltage -112 272 R0
SYMATTR InstName V3
SYMATTR Value 9
SYMBOL res 608 656 R0
SYMATTR InstName R2
SYMATTR Value 7.5k
SYMBOL voltage -224 272 R0
SYMATTR InstName V4
SYMATTR Value 5
SYMBOL schottky 640 1248 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D2
SYMATTR Value 1N5819
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 512 800 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 1k
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SYMATTR InstName R5
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SYMATTR InstName R6
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SYMATTR InstName L1
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WINDOW 0 0 56 VBottom 2
WINDOW 3 -26 0 VTop 2
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SYMATTR Value 1K
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WINDOW 3 16 -10 Left 2
SYMATTR Value LM324
SYMATTR InstName U3
SYMATTR SpiceModel lm324
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WINDOW 0 46 40 Left 2
SYMATTR InstName R9
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SYMATTR InstName M1
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WINDOW 0 0 56 VBottom 2
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SYMATTR InstName M2
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SYMATTR Value 100
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WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R14
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SYMATTR InstName M3
SYMATTR Value PMV31XN
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SYMATTR Value PMV31XN
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SYMATTR InstName M5
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SYMATTR Value PMV33UPE
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WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
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SYMATTR Type diode
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TEXT -920 256 Left 2 !.tran 3 startup uic
TEXT 632 1520 Left 2 ;P-Channel
TEXT 376 1520 Left 2 ;N-Channel
TEXT 664 1656 Left 2 ;S
TEXT 664 1880 Left 2 ;D
TEXT 360 1648 Left 2 ;D
TEXT 360 1776 Left 2 ;S
TEXT 360 1872 Left 2 ;S
TEXT 664 1768 Left 2 ;D
TEXT 360 2008 Left 2 ;D
TEXT 664 2008 Left 2 ;S
TEXT 880 1520 Left 2 ;P-Channel driver
TEXT -928 384 Left 2 !.inc PMV31XN.lib
TEXT -928 424 Left 2 !.inc PMV33UPE.lib
TEXT -928 464 Left 2 !.inc lm324.lib
TEXT -1040 960 Left 2 ;ZCD and gate trigger
TEXT -1144 1600 Left 2 ;Audio and NPN-PNP gate circuit
TEXT -712 744 Left 2 ;unit gain difference amp
TEXT -184 840 Left 2 ;ensure V > -0.6
TEXT 688 1208 Left 2 ;clamp to GND
TEXT 712 608 Left 2 ;John Fields idea to use D-type flip flop for gate control
TEXT -632 136 Left 2 ;uController will signal gate ON/OFF but actual switching will be subject to ZCD.
TEXT -1304 2088 Left 2 ;*** ZCD output goes wonky when f > 1000Hz or so
TEXT 40 1256 Left 2 ;5 mV




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

 

[George Herold]

On Tuesday, June 10, 2014 5:57:14 PM UTC-4, Douglas Beeson wrote:

Hello all,



I'm back again with an audio zero-cross detection circuit that I have designed based on valuable feedback from some of you (notably Jim Thompson and John Fields). I am trying to gate an audio signal while avoiding clicks as it switches on and off.



I'm submitting the LTSpice file here for your comments and also to ask why one thing does not seem to be working as intended:



The output from the two LM339 comparators seems to go all to hell once some part of input frequency goes over 1000 Hz or so. It all works fine at lower frequencies, and if there is just one comparator instead of two (but I need two to handle zeroes at rising and falling). I haven't built the actual circuit in real parts (lab is a bit of a mess at the moment), but LTSpice is usually far wiser than me, so I must have a flaw in the logic somewhere!

Thanks for your comments and help.

doug beeson

<big snip of circuit...I didn't look at it.>
Did you put pull up resistors on the open collector output of the LM339?
(a few k.)
George H.

 

[Jim Thompson]

On Tue, 10 Jun 2014 17:57:14 -0400, Douglas Beeson
<c.difficile@gmail.com> wrote:

Hello all,

I'm back again with an audio zero-cross detection circuit that I have designed based on valuable feedback from some of you (notably Jim Thompson and John Fields). I am trying to gate an audio signal while avoiding clicks as it switches on and off.

I'm submitting the LTSpice file here for your comments and also to ask why one thing does not seem to be working as intended:

The output from the two LM339 comparators seems to go all to hell once some part of input frequency goes over 1000 Hz or so. It all works fine at lower frequencies, and if there is just one comparator instead of two (but I need two to handle zeroes at rising and falling). I haven't built the actual circuit in real parts (lab is a bit of a mess at the moment), but LTSpice is usually far wiser than me, so I must have a flaw in the logic somewhere!

Thanks for your comments and help.

doug beeson

PS: Links for the referenced libraries are here:
https://dl.dropboxusercontent.com/u/2156133/lm324.lib
https://dl.dropboxusercontent.com/u/2156133/LM339.lib
https://dl.dropboxusercontent.com/u/2156133/PMV31XN.lib
https://dl.dropboxusercontent.com/u/2156133/PMV33UPE.lib


Version 4
SHEET 1 1752 2420
WIRE -384 208 -384 192
WIRE -224 256 -224 240
WIRE -112 256 -112 240
WIRE 0 256 0 240
WIRE -384 288 -384 208
WIRE -224 288 -224 256
WIRE -112 288 -112 256
WIRE 0 288 0 256
WIRE -384 448 -384 368
WIRE -224 448 -224 368
WIRE -224 448 -384 448

[snip, full asc listing at...]
[Message-Id:<20140610175714.c9fe263bc96a36dd90f7ef8b@gmail.com>]

TEXT 712 608 Left 2 ;John Fields idea to use D-type flip flop for gate control
TEXT -632 136 Left 2 ;uController will signal gate ON/OFF but actual switching will be subject to ZCD.
TEXT -1304 2088 Left 2 ;*** ZCD output goes wonky when f > 1000Hz or so
TEXT 40 1256 Left 2 ;5 mV

Missing symbols: LM339, cd4013b.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| 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 Tue, 10 Jun 2014 16:59:15 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Tue, 10 Jun 2014 17:57:14 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

Hello all,

I'm back again with an audio zero-cross detection circuit that I have designed based on valuable feedback from some of you (notably Jim Thompson and John Fields). I am trying to gate an audio signal while avoiding clicks as it switches on and off.

I'm submitting the LTSpice file here for your comments and also to ask why one thing does not seem to be working as intended:

The output from the two LM339 comparators seems to go all to hell once some part of input frequency goes over 1000 Hz or so. It all works fine at lower frequencies, and if there is just one comparator instead of two (but I need two to handle zeroes at rising and falling). I haven't built the actual circuit in real parts (lab is a bit of a mess at the moment), but LTSpice is usually far wiser than me, so I must have a flaw in the logic somewhere!

Thanks for your comments and help.

doug beeson

PS: Links for the referenced libraries are here:
https://dl.dropboxusercontent.com/u/2156133/lm324.lib
https://dl.dropboxusercontent.com/u/2156133/LM339.lib
https://dl.dropboxusercontent.com/u/2156133/PMV31XN.lib
https://dl.dropboxusercontent.com/u/2156133/PMV33UPE.lib


Version 4
SHEET 1 1752 2420
WIRE -384 208 -384 192
WIRE -224 256 -224 240
WIRE -112 256 -112 240
WIRE 0 256 0 240
WIRE -384 288 -384 208
WIRE -224 288 -224 256
WIRE -112 288 -112 256
WIRE 0 288 0 256
WIRE -384 448 -384 368
WIRE -224 448 -224 368
WIRE -224 448 -384 448
[snip, full asc listing at...]
[Message-Id:<20140610175714.c9fe263bc96a36dd90f7ef8b@gmail.com>]
TEXT 712 608 Left 2 ;John Fields idea to use D-type flip flop for gate control
TEXT -632 136 Left 2 ;uController will signal gate ON/OFF but actual switching will be subject to ZCD.
TEXT -1304 2088 Left 2 ;*** ZCD output goes wonky when f > 1000Hz or so
TEXT 40 1256 Left 2 ;5 mV

Missing symbols: LM339, cd4013b.

...Jim Thompson

Also, I'd guess you aren't getting fast enough risetime out of the
LM339's

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

On Tue, 10 Jun 2014 16:59:15 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Tue, 10 Jun 2014 17:57:14 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

Hello all,

I'm back again with an audio zero-cross detection circuit that I have designed based on valuable feedback from some of you (notably Jim Thompson and John Fields). I am trying to gate an audio signal while avoiding clicks as it switches on and off.

I'm submitting the LTSpice file here for your comments and also to ask why one thing does not seem to be working as intended:

The output from the two LM339 comparators seems to go all to hell once some part of input frequency goes over 1000 Hz or so. It all works fine at lower frequencies, and if there is just one comparator instead of two (but I need two to handle zeroes at rising and falling). I haven't built the actual circuit in real parts (lab is a bit of a mess at the moment), but LTSpice is usually far wiser than me, so I must have a flaw in the logic somewhere!

Thanks for your comments and help.

doug beeson

PS: Links for the referenced libraries are here:
https://dl.dropboxusercontent.com/u/2156133/lm324.lib
https://dl.dropboxusercontent.com/u/2156133/LM339.lib
https://dl.dropboxusercontent.com/u/2156133/PMV31XN.lib
https://dl.dropboxusercontent.com/u/2156133/PMV33UPE.lib


Version 4
SHEET 1 1752 2420
WIRE -384 208 -384 192
WIRE -224 256 -224 240
WIRE -112 256 -112 240
WIRE 0 256 0 240
WIRE -384 288 -384 208
WIRE -224 288 -224 256
WIRE -112 288 -112 256
WIRE 0 288 0 256
WIRE -384 448 -384 368
WIRE -224 448 -224 368
WIRE -224 448 -384 448
[snip, full asc listing at...]
[Message-Id:<20140610175714.c9fe263bc96a36dd90f7ef8b@gmail.com>]
TEXT 712 608 Left 2 ;John Fields idea to use D-type flip flop for gate control
TEXT -632 136 Left 2 ;uController will signal gate ON/OFF but actual switching will be subject to ZCD.
TEXT -1304 2088 Left 2 ;*** ZCD output goes wonky when f > 1000Hz or so
TEXT 40 1256 Left 2 ;5 mV

Missing symbols: LM339, cd4013b.

My apologies:
https://dl.dropboxusercontent.com/u/2156133/cd4013b.asy
https://dl.dropboxusercontent.com/u/2156133/LM339.asy

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

 

[John Fields]

On Tue, 10 Jun 2014 17:57:14 -0400, Douglas Beeson
<c.difficile@gmail.com> wrote:

Hello all,

I'm back again with an audio zero-cross detection circuit that I have designed based on valuable feedback from some of you (notably Jim Thompson and John Fields). I am trying to gate an audio signal while avoiding clicks as it switches on and off.

I'm submitting the LTSpice file here for your comments and also to ask why one thing does not seem to be working as intended:

The output from the two LM339 comparators seems to go all to hell once some part of input frequency goes over 1000 Hz or so. It all works fine at lower frequencies, and if there is just one comparator instead of two (but I need two to handle zeroes at rising and falling). I haven't built the actual circuit in real parts (lab is a bit of a mess at the moment), but LTSpice is usually far wiser than me, so I must have a flaw in the logic somewhere!

Thanks for your comments and help.

doug beeson

---
Doug,

After the last go-round I worked on my circuit and got to rev. J (!)
before I was happy with it, but didn't post anything because (as I
recall) interest seemed to have waned.

In any case, here's the file:

Version 4
SHEET 1 1872 1348
WIRE 576 -16 576 -48
WIRE 880 64 880 -48
WIRE -784 112 -880 112
WIRE -144 112 -784 112
WIRE 576 112 576 64
WIRE 672 112 576 112
WIRE 816 112 752 112
WIRE 576 128 576 112
WIRE -784 160 -784 112
WIRE -144 160 -144 112
WIRE -144 160 -160 160
WIRE -160 176 -160 160
WIRE -144 176 -144 160
WIRE 0 176 -16 176
WIRE 352 176 192 176
WIRE 400 176 352 176
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WIRE -640 256 -640 224
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WIRE -160 256 -160 240
WIRE -160 256 -176 256
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WIRE -144 256 -160 256
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WIRE 1088 304 1088 240
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WIRE -16 320 -16 272
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WIRE 1040 384 992 384
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WIRE -320 560 -640 560
WIRE -240 560 -240 192
WIRE -240 560 -320 560
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WIRE -144 560 -240 560
WIRE -16 560 -16 400
WIRE -16 560 -144 560
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WIRE 576 560 -16 560
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WIRE 1088 608 1088 576
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WIRE 384 656 352 656
WIRE 512 656 464 656
WIRE 880 672 880 432
WIRE -1120 704 -1120 560
WIRE 576 720 576 704
WIRE 688 720 576 720
WIRE 816 720 768 720
WIRE 352 736 352 656
WIRE 1088 752 1088 688
WIRE 576 768 576 720
WIRE 880 864 880 768
WIRE 352 880 352 816
WIRE 576 880 576 848
FLAG -1120 704 0
FLAG -1088 416 0V
FLAG 96 96 0V
FLAG 96 320 MR
FLAG -752 272 MR
FLAG -16 272 ONOFF
FLAG -464 192 AC
FLAG -1120 160 12
FLAG -1008 176 -12
FLAG -608 224 ACIN
FLAG 576 -48 12
FLAG 880 -48 12
FLAG 880 864 -12
FLAG 576 880 -12
FLAG 352 880 -12
FLAG 1088 240 AC
FLAG 1120 576 ACOUT
FLAG 1088 752 0
SYMBOL voltage -640 336 R0
WINDOW 0 38 56 Left 2
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V3
SYMATTR Value SINE(0 2 349.23)
SYMBOL voltage -880 240 R0
WINDOW 0 37 61 Left 2
WINDOW 3 22 99 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL cap -560 240 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C2
SYMATTR Value 10ku
SYMBOL voltage -16 304 R0
WINDOW 0 38 56 Left 2
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V4
SYMATTR Value PULSE(0 5 .1 100n 100n .4)
SYMBOL CD4013B 96 96 R0
SYMATTR InstName U2
SYMBOL cap -800 160 R0
SYMATTR InstName C1
SYMATTR Value 10n
SYMBOL res -800 304 R0
SYMATTR InstName R1
SYMATTR Value 10k
SYMBOL res -336 208 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R2
SYMATTR Value 10k
SYMBOL res -336 304 R0
SYMATTR InstName R3
SYMATTR Value 130
SYMBOL Comparators\\LT1719 -160 144 R0
SYMATTR InstName U1
SYMBOL voltage -640 240 R0
WINDOW 0 38 56 Left 2
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value SINE(0 2 261.63)
SYMBOL voltage -1120 240 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V5
SYMATTR Value 12
SYMBOL voltage -1008 240 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V6
SYMATTR Value -12
SYMBOL npn 512 128 R0
SYMATTR InstName Q3
SYMATTR Value 2N5089
SYMBOL res 496 160 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R9
SYMATTR Value 10k
SYMBOL res 560 -32 R0
SYMATTR InstName R10
SYMATTR Value 1000
SYMBOL pnp 816 160 M180
WINDOW 0 67 32 Left 2
WINDOW 3 52 57 Left 2
SYMATTR InstName Q4
SYMATTR Value 2N5771
SYMBOL res 768 96 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R11
SYMATTR Value 1000
SYMBOL res 784 704 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R12
SYMATTR Value 1000
SYMBOL pnp 512 704 M180
WINDOW 0 67 32 Left 2
WINDOW 3 52 57 Left 2
SYMATTR InstName Q5
SYMATTR Value 2N5771
SYMBOL npn 816 672 R0
SYMATTR InstName Q6
SYMATTR Value 2N5089
SYMBOL res 560 752 R0
SYMATTR InstName R13
SYMATTR Value 1000
SYMBOL res 480 640 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R14
SYMATTR Value 1000
SYMBOL res 336 224 R0
SYMATTR InstName R15
SYMATTR Value 1000
SYMBOL res 336 720 R0
SYMATTR InstName R16
SYMATTR Value 4.7k
SYMBOL nmos 1040 304 R0
SYMATTR InstName M1
SYMATTR Value BSC010NE2LSI
SYMBOL res 1072 592 R0
SYMATTR InstName R4
SYMATTR Value 6
SYMBOL nmos 1040 560 M180
SYMATTR InstName M2
SYMATTR Value BSC010NE2LSI
SYMBOL voltage -640 432 R0
WINDOW 0 38 56 Left 2
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V7
SYMATTR Value SINE(0 2 392)
TEXT -1104 592 Left 2 !.tran .6 startup uic
TEXT -1104 616 Left 2 !.include CD4000.lib
TEXT -1104 640 Left 2 !.model SW SW(Ron=.01 Roff=1G Vt=2.5 Vh=0)
TEXT -304 600 Left 3 ;ZERO-CROSSING SWITCH, REV J
TEXT -304 640 Left 3 ;John Fields, 17 May 2014
TEXT -1104 664 Left 2 !.wave C:\\sed\\spice\\zcd2revj.wav 8 44.1K
V(acout)


V2, V3, and V7 are just to see how the cicuit responds to a
variable-frequency variable-amplitude input, and the output looks
pretty good. Not the best FFT in the world, but not the worst,
either...

Also, to check the high freq response I changed ACIN to 20kHz, and
as ONOFF went high and low, ACOUT got switched right at the zero
crossings, as expected.

Just for grins, I had LTspice generate a .wav file so ACOUT could be
listened to, and the switching transitions are nice and clean.

One caveat: The LT1719 is in there because it has a common mode
range which includes 100mV below the negative rail (ground, in this
case) so substituting comparators which don't may be a bad idea.

 

[Douglas Beeson]

On Tue, 10 Jun 2014 17:05:26 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Tue, 10 Jun 2014 16:59:15 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Tue, 10 Jun 2014 17:57:14 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

Hello all,

I'm back again with an audio zero-cross detection circuit that I have designed based on valuable feedback from some of you (notably Jim Thompson and John Fields). I am trying to gate an audio signal while avoiding clicks as it switches on and off.

I'm submitting the LTSpice file here for your comments and also to ask why one thing does not seem to be working as intended:

The output from the two LM339 comparators seems to go all to hell once some part of input frequency goes over 1000 Hz or so. It all works fine at lower frequencies, and if there is just one comparator instead of two (but I need two to handle zeroes at rising and falling). I haven't built the actual circuit in real parts (lab is a bit of a mess at the moment), but LTSpice is usually far wiser than me, so I must have a flaw in the logic somewhere!

Thanks for your comments and help.

doug beeson

PS: Links for the referenced libraries are here:
https://dl.dropboxusercontent.com/u/2156133/lm324.lib
https://dl.dropboxusercontent.com/u/2156133/LM339.lib
https://dl.dropboxusercontent.com/u/2156133/PMV31XN.lib
https://dl.dropboxusercontent.com/u/2156133/PMV33UPE.lib


Version 4
SHEET 1 1752 2420
WIRE -384 208 -384 192
WIRE -224 256 -224 240
WIRE -112 256 -112 240
WIRE 0 256 0 240
WIRE -384 288 -384 208
WIRE -224 288 -224 256
WIRE -112 288 -112 256
WIRE 0 288 0 256
WIRE -384 448 -384 368
WIRE -224 448 -224 368
WIRE -224 448 -384 448
[snip, full asc listing at...]
[Message-Id:<20140610175714.c9fe263bc96a36dd90f7ef8b@gmail.com>]
TEXT 712 608 Left 2 ;John Fields idea to use D-type flip flop for gate control
TEXT -632 136 Left 2 ;uController will signal gate ON/OFF but actual switching will be subject to ZCD.
TEXT -1304 2088 Left 2 ;*** ZCD output goes wonky when f > 1000Hz or so
TEXT 40 1256 Left 2 ;5 mV

Missing symbols: LM339, cd4013b.

...Jim Thompson

Also, I'd guess you aren't getting fast enough risetime out of the
LM339's

Oh, duh. I just went back and checked the datasheet. It states 0.75 us rise time on 5mV overdrive. I am not familiar with the term "overdrive", but the graph seems to show a step input of that magnitude and the corresponding rise time of the output. When I measure the non-truncated LM339 output in the spice simulation it gives me about 3 us rise. So way too slow to handle a higher frequency input.

Should I filter or just let the CD4013 ignore the transitions it doesn't see as valid?

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

 

[Douglas Beeson]

On Tue, 10 Jun 2014 17:53:54 -0700 (PDT)
George Herold <gherold@teachspin.com> wrote:

On Tuesday, June 10, 2014 5:57:14 PM UTC-4, Douglas Beeson wrote:
Hello all,



I'm back again with an audio zero-cross detection circuit that I have designed based on valuable feedback from some of you (notably Jim Thompson and John Fields). I am trying to gate an audio signal while avoiding clicks as it switches on and off.



I'm submitting the LTSpice file here for your comments and also to ask why one thing does not seem to be working as intended:



The output from the two LM339 comparators seems to go all to hell once some part of input frequency goes over 1000 Hz or so. It all works fine at lower frequencies, and if there is just one comparator instead of two (but I need two to handle zeroes at rising and falling). I haven't built the actual circuit in real parts (lab is a bit of a mess at the moment), but LTSpice is usually far wiser than me, so I must have a flaw in the logic somewhere!

Thanks for your comments and help.

doug beeson

big snip of circuit...I didn't look at it.
Did you put pull up resistors on the open collector output of the LM339?

Yes, I have 7.5k pulling up to 5V. From the LM339 datasheet it looks like I am asking too much of the comparators to respond to 8kHz. Gotta decide whether to filter the input or ignore the bad outputs.

Thanks~
doug

(a few k.)
George H.

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

 

[Douglas Beeson]

On Wed, 11 Jun 2014 01:51:35 -0500
John Fields <jfields@austininstruments.com> wrote:

On Tue, 10 Jun 2014 17:57:14 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

Hello all,

I'm back again with an audio zero-cross detection circuit that I have designed based on valuable feedback from some of you (notably Jim Thompson and John Fields). I am trying to gate an audio signal while avoiding clicks as it switches on and off.

I'm submitting the LTSpice file here for your comments and also to ask why one thing does not seem to be working as intended:

The output from the two LM339 comparators seems to go all to hell once some part of input frequency goes over 1000 Hz or so. It all works fine at lower frequencies, and if there is just one comparator instead of two (but I need two to handle zeroes at rising and falling). I haven't built the actual circuit in real parts (lab is a bit of a mess at the moment), but LTSpice is usually far wiser than me, so I must have a flaw in the logic somewhere!

Thanks for your comments and help.

doug beeson

---
Doug,

After the last go-round I worked on my circuit and got to rev. J (!)
before I was happy with it, but didn't post anything because (as I
recall) interest seemed to have waned.

Oh no, not at all! Your last circuits gave me so many ideas that I went off and played with them for a few weeks. I really, really appreciate your input. I'm just floored by all stuff I don't know about LTSpice and about making simple circuits that work. One of those Rumsfeld moments of not knowing what you don't know...

In any case, here's the file:

Version 4
SHEET 1 1872 1348
WIRE 576 -16 576 -48
WIRE 880 64 880 -48
WIRE -784 112 -880 112
WIRE -144 112 -784 112
WIRE 576 112 576 64
WIRE 672 112 576 112
WIRE 816 112 752 112
WIRE 576 128 576 112
WIRE -784 160 -784 112
WIRE -144 160 -144 112
WIRE -144 160 -160 160
WIRE -160 176 -160 160
WIRE -144 176 -144 160
WIRE 0 176 -16 176
WIRE 352 176 192 176
WIRE 400 176 352 176
WIRE 512 176 480 176
WIRE -192 192 -240 192
WIRE 0 208 -128 208
WIRE -608 224 -640 224
WIRE -560 224 -608 224
WIRE -464 224 -464 192
WIRE -464 224 -496 224
WIRE -432 224 -464 224
WIRE -320 224 -352 224
WIRE -192 224 -320 224
WIRE 352 240 352 176
WIRE -1120 256 -1120 160
WIRE -1008 256 -1008 176
WIRE -880 256 -880 112
WIRE -640 256 -640 224
WIRE -176 256 -176 240
WIRE -160 256 -160 240
WIRE -160 256 -176 256
WIRE -144 256 -144 240
WIRE -144 256 -160 256
WIRE -784 272 -784 224
WIRE -752 272 -784 272
WIRE -16 272 -16 176
WIRE 1088 304 1088 240
WIRE -784 320 -784 272
WIRE -320 320 -320 224
WIRE -16 320 -16 272
WIRE -640 352 -640 336
WIRE 1040 384 992 384
WIRE -1120 416 -1120 336
WIRE -1088 416 -1120 416
WIRE 880 432 880 160
WIRE 992 432 992 384
WIRE 992 432 880 432
WIRE -640 448 -640 432
WIRE 1088 464 1088 400
WIRE 992 480 992 432
WIRE 1040 480 992 480
WIRE -1120 560 -1120 416
WIRE -1008 560 -1008 336
WIRE -1008 560 -1120 560
WIRE -880 560 -880 336
WIRE -880 560 -1008 560
WIRE -784 560 -784 400
WIRE -784 560 -880 560
WIRE -640 560 -640 528
WIRE -640 560 -784 560
WIRE -320 560 -320 400
WIRE -320 560 -640 560
WIRE -240 560 -240 192
WIRE -240 560 -320 560
WIRE -144 560 -144 256
WIRE -144 560 -240 560
WIRE -16 560 -16 400
WIRE -16 560 -144 560
WIRE 576 560 576 224
WIRE 576 560 -16 560
WIRE 1088 576 1088 560
WIRE 1120 576 1088 576
WIRE 576 608 576 560
WIRE 1088 608 1088 576
WIRE 352 656 352 320
WIRE 384 656 352 656
WIRE 512 656 464 656
WIRE 880 672 880 432
WIRE -1120 704 -1120 560
WIRE 576 720 576 704
WIRE 688 720 576 720
WIRE 816 720 768 720
WIRE 352 736 352 656
WIRE 1088 752 1088 688
WIRE 576 768 576 720
WIRE 880 864 880 768
WIRE 352 880 352 816
WIRE 576 880 576 848
FLAG -1120 704 0
FLAG -1088 416 0V
FLAG 96 96 0V
FLAG 96 320 MR
FLAG -752 272 MR
FLAG -16 272 ONOFF
FLAG -464 192 AC
FLAG -1120 160 12
FLAG -1008 176 -12
FLAG -608 224 ACIN
FLAG 576 -48 12
FLAG 880 -48 12
FLAG 880 864 -12
FLAG 576 880 -12
FLAG 352 880 -12
FLAG 1088 240 AC
FLAG 1120 576 ACOUT
FLAG 1088 752 0
SYMBOL voltage -640 336 R0
WINDOW 0 38 56 Left 2
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V3
SYMATTR Value SINE(0 2 349.23)
SYMBOL voltage -880 240 R0
WINDOW 0 37 61 Left 2
WINDOW 3 22 99 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL cap -560 240 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C2
SYMATTR Value 10ku
SYMBOL voltage -16 304 R0
WINDOW 0 38 56 Left 2
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V4
SYMATTR Value PULSE(0 5 .1 100n 100n .4)
SYMBOL CD4013B 96 96 R0
SYMATTR InstName U2
SYMBOL cap -800 160 R0
SYMATTR InstName C1
SYMATTR Value 10n
SYMBOL res -800 304 R0
SYMATTR InstName R1
SYMATTR Value 10k
SYMBOL res -336 208 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R2
SYMATTR Value 10k
SYMBOL res -336 304 R0
SYMATTR InstName R3
SYMATTR Value 130
SYMBOL Comparators\\LT1719 -160 144 R0
SYMATTR InstName U1
SYMBOL voltage -640 240 R0
WINDOW 0 38 56 Left 2
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value SINE(0 2 261.63)
SYMBOL voltage -1120 240 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V5
SYMATTR Value 12
SYMBOL voltage -1008 240 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V6
SYMATTR Value -12
SYMBOL npn 512 128 R0
SYMATTR InstName Q3
SYMATTR Value 2N5089
SYMBOL res 496 160 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R9
SYMATTR Value 10k
SYMBOL res 560 -32 R0
SYMATTR InstName R10
SYMATTR Value 1000
SYMBOL pnp 816 160 M180
WINDOW 0 67 32 Left 2
WINDOW 3 52 57 Left 2
SYMATTR InstName Q4
SYMATTR Value 2N5771
SYMBOL res 768 96 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R11
SYMATTR Value 1000
SYMBOL res 784 704 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R12
SYMATTR Value 1000
SYMBOL pnp 512 704 M180
WINDOW 0 67 32 Left 2
WINDOW 3 52 57 Left 2
SYMATTR InstName Q5
SYMATTR Value 2N5771
SYMBOL npn 816 672 R0
SYMATTR InstName Q6
SYMATTR Value 2N5089
SYMBOL res 560 752 R0
SYMATTR InstName R13
SYMATTR Value 1000
SYMBOL res 480 640 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R14
SYMATTR Value 1000
SYMBOL res 336 224 R0
SYMATTR InstName R15
SYMATTR Value 1000
SYMBOL res 336 720 R0
SYMATTR InstName R16
SYMATTR Value 4.7k
SYMBOL nmos 1040 304 R0
SYMATTR InstName M1
SYMATTR Value BSC010NE2LSI
SYMBOL res 1072 592 R0
SYMATTR InstName R4
SYMATTR Value 6
SYMBOL nmos 1040 560 M180
SYMATTR InstName M2
SYMATTR Value BSC010NE2LSI
SYMBOL voltage -640 432 R0
WINDOW 0 38 56 Left 2
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V7
SYMATTR Value SINE(0 2 392)
TEXT -1104 592 Left 2 !.tran .6 startup uic
TEXT -1104 616 Left 2 !.include CD4000.lib
TEXT -1104 640 Left 2 !.model SW SW(Ron=.01 Roff=1G Vt=2.5 Vh=0)
TEXT -304 600 Left 3 ;ZERO-CROSSING SWITCH, REV J
TEXT -304 640 Left 3 ;John Fields, 17 May 2014
TEXT -1104 664 Left 2 !.wave C:\\sed\\spice\\zcd2revj.wav 8 44.1K
V(acout)


V2, V3, and V7 are just to see how the cicuit responds to a
variable-frequency variable-amplitude input, and the output looks
pretty good. Not the best FFT in the world, but not the worst,
either...

Also, to check the high freq response I changed ACIN to 20kHz, and
as ONOFF went high and low, ACOUT got switched right at the zero
crossings, as expected.

That's where my slow LM339 solution is bombing out. I'm going to have to look into the LT1719.

Just for grins, I had LTspice generate a .wav file so ACOUT could be
listened to, and the switching transitions are nice and clean.

I never knew that was possible! I am also going to play with using a WAV file as input to a voltage source.

One caveat: The LT1719 is in there because it has a common mode
range which includes 100mV below the negative rail (ground, in this
case) so substituting comparators which don't may be a bad idea.

I'm a little confused by the term "common mode range". I always thought that "common mode" meant that part of a signal that was common to two inputs, say in a differential amplifier that is pulling 100mV signal differences out of two inputs that have a common 30V level. But seeing the LT1719 datasheet, and your comment here, it sounds like "common mode range" really just means the absolute value that the input signal can take without invalidating the device output.

Thank you again for all your help, John.

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

 

[John Fields]

On Wed, 11 Jun 2014 12:49:38 -0400, Douglas Beeson
<c.difficile@gmail.com> wrote:


>I'm a little confused by the term "common mode range". I always thought that "common mode" meant that part of a signal that was common to two inputs, say in a differential amplifier that is pulling 100mV signal differences out of two inputs that have a common 30V level. But seeing the LT1719 datasheet, and your comment here, it sounds like "common mode range" really just means the absolute value that the input signal can take without invalidating the device output.

---
Kinda.

What the common mode range is is the limits between which the inputs
must stay in order for the device to work within its spec's.

For example, if a single-supply device is powered with +5V on Vcc
and 0V on Vss and its input common-mode range spec is from Vcc-1V to
Vss +1V, then the inputs must stay between 4V and 1V when a
comparison is being made.

On some comparators, though, once the comparison has been made and
the output has settled, the inputs may move out of the common-mode
region without affecting the output.

That's only _some_ comparators, however, and if that kind of
operation is necessary, then CYA is in order and the data sheet or,
better yet, the manufacturer needs to be consulted.
---

>Thank you again for all your help, John.

---
My pleasure.

John Fields

 

[Jasen Betts]

On 2014-06-10, Douglas Beeson <c.difficile@gmail.com> wrote:

Hello all,

I'm back again with an audio zero-cross detection circuit that I
have designed based on valuable feedback from some of you (notably Jim
Thompson and John Fields). I am trying to gate an audio signal while
avoiding clicks as it switches on and off.

zero crossing detection won't get you there.
interrupting the signal at its steepest slope wont give good results.


--
umop apisdn


--- news://freenews.netfront.net/ - complaints: news@netfront.net ---

 

[Douglas Beeson]

On 13 Jun 2014 12:24:31 GMT
Jasen Betts <jasen@xnet.co.nz> wrote:

On 2014-06-10, Douglas Beeson <c.difficile@gmail.com> wrote:
Hello all,

I'm back again with an audio zero-cross detection circuit that I
have designed based on valuable feedback from some of you (notably Jim
Thompson and John Fields). I am trying to gate an audio signal while
avoiding clicks as it switches on and off.

zero crossing detection won't get you there.
interrupting the signal at its steepest slope wont give good results.

I can imagine that switching on voltage zeroes might lead to current surges from the voice coil. I could try detecting current zero crosses. Do you have another suggestion?

d

--
umop apisdn


--- news://freenews.netfront.net/ - complaints: news@netfront.net ---

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

 

[Jim Thompson]

On Fri, 13 Jun 2014 11:13:44 -0400, Douglas Beeson
<c.difficile@gmail.com> wrote:

On 13 Jun 2014 12:24:31 GMT
Jasen Betts <jasen@xnet.co.nz> wrote:

On 2014-06-10, Douglas Beeson <c.difficile@gmail.com> wrote:
Hello all,

I'm back again with an audio zero-cross detection circuit that I
have designed based on valuable feedback from some of you (notably Jim
Thompson and John Fields). I am trying to gate an audio signal while
avoiding clicks as it switches on and off.

zero crossing detection won't get you there.
interrupting the signal at its steepest slope wont give good results.

I can imagine that switching on voltage zeroes might lead to current surges from the voice coil. I could try detecting current zero crosses. Do you have another suggestion?

d



--
umop apisdn


--- news://freenews.netfront.net/ - complaints: news@netfront.net ---

In the audio biz they "fade" from one source to another.

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

 

[Grant]

On Fri, 13 Jun 2014 08:18:15 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Fri, 13 Jun 2014 11:13:44 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

On 13 Jun 2014 12:24:31 GMT
Jasen Betts <jasen@xnet.co.nz> wrote:

On 2014-06-10, Douglas Beeson <c.difficile@gmail.com> wrote:
Hello all,

I'm back again with an audio zero-cross detection circuit that I
have designed based on valuable feedback from some of you (notably Jim
Thompson and John Fields). I am trying to gate an audio signal while
avoiding clicks as it switches on and off.

zero crossing detection won't get you there.
interrupting the signal at its steepest slope wont give good results.

I can imagine that switching on voltage zeroes might lead to current surges from the voice coil. I could try detecting current zero crosses. Do you have another suggestion?

d



--
umop apisdn


--- news://freenews.netfront.net/ - complaints: news@netfront.net ---

In the audio biz they "fade" from one source to another.

This fading is what you want to eliminate clicks, not a sudden switch.

Grant.

...Jim Thompson

 

[Maynard A. Philbrook Jr.]

In article <20140613111344.71d43c28685c2ce51289fd1d@gmail.com>,
c.difficile@gmail.com says...

On 13 Jun 2014 12:24:31 GMT
Jasen Betts <jasen@xnet.co.nz> wrote:

On 2014-06-10, Douglas Beeson <c.difficile@gmail.com> wrote:
Hello all,

I'm back again with an audio zero-cross detection circuit that I
have designed based on valuable feedback from some of you (notably Jim
Thompson and John Fields). I am trying to gate an audio signal while
avoiding clicks as it switches on and off.

zero crossing detection won't get you there.
interrupting the signal at its steepest slope wont give good results.

I can imagine that switching on voltage zeroes might lead to current surges from the voice coil. I could try detecting current zero crosses. Do you have another suggestion?

You would need the circuit monitoring both inputs and waiting for both
to appear at zero at the same time before performing the switch.

The change of that happening is going to cause delay in your switch
depending on how low of level you are sensing.
Even if you did that, you're still going to have issues due to higher
freqs on top of the lower ones. You'll get a zero sense for a moment and
do the switch while there is still content in the lower freq spectrum on
the new input, which still leads to noise. I guess if you are dealing
with single tones you would not need to worry, but I don't think that is
the case here.

The standard method is to slowly reduce gain on input going away while
increasing the gain coming in. This can take place is a very short time.

Jamie

 

[Michael A. Terrell]

Jim Thompson wrote:

On Fri, 13 Jun 2014 11:13:44 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

On 13 Jun 2014 12:24:31 GMT
Jasen Betts <jasen@xnet.co.nz> wrote:

On 2014-06-10, Douglas Beeson <c.difficile@gmail.com> wrote:
Hello all,

I'm back again with an audio zero-cross detection circuit that I
have designed based on valuable feedback from some of you (notably Jim
Thompson and John Fields). I am trying to gate an audio signal while
avoiding clicks as it switches on and off.

zero crossing detection won't get you there.
interrupting the signal at its steepest slope wont give good results.

I can imagine that switching on voltage zeroes might lead to current surges from the voice coil. I could try detecting current zero crosses. Do you have another suggestion?

d



--
umop apisdn


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In the audio biz they "fade" from one source to another.

The attenuators on the consoles I maintained were speced to - 80 dB
when turned all the way down.


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

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[John Fields]

On 13 Jun 2014 12:24:31 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:

On 2014-06-10, Douglas Beeson <c.difficile@gmail.com> wrote:
Hello all,

I'm back again with an audio zero-cross detection circuit that I
have designed based on valuable feedback from some of you (notably Jim
Thompson and John Fields). I am trying to gate an audio signal while
avoiding clicks as it switches on and off.

zero crossing detection won't get you there.
interrupting the signal at its steepest slope wont give good results.

---
Sounds like nonsense to me; have you tried it?

If not, note that the sim generates a .wav file which you can play
and listen for clicks. I did, and heard nothing go awry.

Since the voice coil, cone, surround, and all those other
loudspeaker moving parts have mass, switching the audio ON at a zero
crossing will start the mass moving gradually from its resting point
in the magnetic field, - thereby approximating a fast fade-in - and
going open-circuit OFF at a zero crossing will allow the mass a
short period of self-damped oscillation before it coasts to a stop,
again gradually.

John Fields