50 kHz VCO w/sine output

On Sep 28, 5:54=A0am, George Herold <gher...@teachspin.com> wrote:

> Finally I offer the following, =A0a Wien bridge oscillator =A0with
> varactor diodes as the capacitors. =A0 =A0I was also thinking I could use

Victoriana!

On Tuesday, September 27, 2011 1:18:06 PM UTC-7, George Herold wrote:
> On Sep 27, 3:40=A0pm, whit3rd <whi...@gmail.com> wrote:
> > On Tuesday, September 27, 2011 9:54:36 AM UTC-7, George Herold wrote:
> > > 30kHz to 100kHz VCO with sine wave output.

> > > Finally I offer the following, =A0a Wien bridge oscillator =A0with
> > > varactor diodes as the capacitors.
> >
> > Not a great choice, because the Wein bridge requires MATCHED
> > capacitors, tuned together, for best performance. =A0 It can be
> > done with a few trimmers (probably easiest to trim the offset + gain
> > of the control voltages). =A0Then, there's the level translation proble=
m
> > (the capacitors in a Wien bridge don't have one end grounded).

> Did you look at my schematic?  I seem to have it running in LTspice.

It looked OK, but (1) tuning voltage of  0 to 30V is typical to get the
full C range of a varicap (and that's gonna go outside most op amp toleranc=
e),
and (2) the amplitude-stabilizing part of a Wien oscillator will
get added in, presumably?  It has to oscillate at low V to keep the
varicaps in their linear range, so they don't frequency-multiply.
Varicap diodes are STILL diodes, they'll rectify if you let the signal
get as big as the bias.

On Sep 27, 4:43=A0pm, Tim Wescott <t...@seemywebsite.com> wrote:
> On Tue, 27 Sep 2011 12:44:44 -0700, George Herold wrote:
> > On Sep 27, 2:17=A0pm, Tim Wescott <t...@seemywebsite.com> wrote:
> >> On Tue, 27 Sep 2011 09:54:36 -0700, George Herold wrote:
> >> > 30kHz to 100kHz VCO with sine wave output.
>
> >> > I know this has been covered before in previous threads.
>
> >> > The obvious way to do this is a digital signal generator (DSG) IC
> >> > with maybe an A-D to measure the voltage. =A0I=92ve not done much di=
gital
> >> > stuff in a while, so this has a bit of a learning curve. =A0But if
> >> > anyone has some good chips to look at or app notes then please do
> >> > share. =A0I've been looking at IC's on Analogs web site, but there a=
re
> >> > a lot to choose from!
>
> >> > I was also thinking I could do this with a ~20MHz varactor controlle=
d
> >> > VCO as a variable clock into a DSG chip. =A0This looks easier to my
> >> > unsophisticated digital mind.
>
> >> > Finally I offer the following, =A0a Wien bridge oscillator =A0with
> >> > varactor diodes as the capacitors. =A0 =A0I was also thinking I coul=
d use
> >> > crappy Z5U ceramic caps instead of the varactors.
>
> >> It'll be rough to get the high impedances and low voltage swings you
> >> need for the Wien bridge oscillator to work either with varactors or
> >> with a suggestion that I've made previously of using JFETs as variable
> >> resistors.
>
> > Hi Tim, =A0I've got a spice simulation with just diode limiting for the
> > varible gain. =A0~1.2 Vp-p on the output. =A0I couldn't find any varact=
ors
> > in LTspice so I just used a diode and added some more C in parallel. Th=
e
> > AC voltage across the 'varactor' is less than a volt. =A0By playing aro=
und
> > with the gain control I can probably get reduce that by a factor of two=
.
> > =A0Is that too much?
>
> The nonlinearity that you're battling isn't the diode conduction -- it's
> the diode's varying capacitance as its reverse voltage changes. =A0It's
> going to be severe at low voltage/high capacitance. =A0I'm _not_ the
> world's smartest SPICE guy, but I do know (more or less) that you want to
> simulate the varactor with a really large-area diode. =A0I _think_ that
> there's an area parameter that you can dink with, if you copy a diode
> model out of the LTSpice library and paste it into your schematic. =A0Or =
go
> out on the World of the Wide Web and find a varactor model.
>
> I'm thinking that if you want to avoid seeing major distortion you want
> to have the AC voltage be more like tens of millivolts, which will leave
> you open to noise problems.

Thanks Tim,  you may be right.  Looking at varactor spec sheets a volt
changes the C by ~10% or so.  (quite non-linear.)  Well the best way
may be to build one and measure it.

George H.
>
> >> So: a high frequency VCO to a DDS chip, or a fixed-frequency reference
> >> to a DDS that you write a frequency to with a micro, or (if you are fo=
r
> >> some reason insisting on "analog only") a VCO feeding a mixer, beating
> >> against a crystal oscillator.
>
> > Yeah DDS from a micro looks like the 'best' path. =A0It's just outside =
my
> > present comfort zone and so hard to predict how long it will take.
>
> It occurs to me that if you're just bound and determined to avoid
> microprocessors that you could do this with switched capacitor
> techniques. =A0This should give you an oscillation frequency that's
> proportional to your switching frequency, and let you make a cruddy old
> VCO out of a 4046 or something. =A0You may even be able to find a switche=
d
> capacitor filter that can be made to oscillate, and save having to roll
> your own.
>
> An alternative would be a 30-100kHz square wave generator, followed by a
> few really good bandpass filters, in bands to cover the frequency range
> (this would be a lot easier if you didn't want that 3:10 ratio). =A0I've
> also seen a counter fed by a higher-frequency clock, and driving
> resistors that have been selected give a sine-wave approximation. =A0If y=
ou
> select your resistors right you can weigh things so that the harmonics up
> to (IIRC) the number of resistors can be suppressed, leaving the
> fundamental unscathed (and leaving you with the problem of where to find
> such precise resistors). =A0This significantly eases your filtering
> requirements.
>
> Of course, you may well be able to spend your time learning your way
> around PIC programming and get a result in the time you could have spent
> doing either of the above. =A0But if you just _have_ to avoid a
> microprocessor, it's a way forward.
>
> --www.wescottdesign.com- Hide quoted text -
>
> - Show quoted text -

On Sep 27, 5:00=A0pm, Joerg <inva...@invalid.invalid> wrote:
> Tim Wescott wrote:
> > On Tue, 27 Sep 2011 13:18:06 -0700, George Herold wrote:
>
> >> On Sep 27, 3:40 pm, whit3rd <whit...@gmail.com> wrote:
> >>> On Tuesday, September 27, 2011 9:54:36 AM UTC-7, George Herold wrote:
> >>>> 30kHz to 100kHz VCO with sine wave output. I was also thinking I
> >>>> could do this with a ~20MHz varactor controlled VCO as a variable
> >>>> clock into a DSG chip. =A0This looks easier to my unsophisticated
> >>>> digital mind.
> >>> Workable, of course, but not exactly a VCO anymore... and there's the
> >>> Nyquist filtering to do afterward.
>
> >>>> Finally I offer the following, =A0a Wien bridge oscillator =A0with
> >>>> varactor diodes as the capacitors.
> >>> Not a great choice, because the Wein bridge requires MATCHED
> >>> capacitors, tuned together, for best performance. =A0 It can be done =
with
> >>> a few trimmers (probably easiest to trim the offset + gain of the
> >>> control voltages). =A0Then, there's the level translation problem (th=
e
> >>> capacitors in a Wien bridge don't have one end grounded).
> >> Hi Whit3rd,
> >> Did you look at my schematic? =A0I seem to have it running in LTspice.
> >>> Good sinewave LC VCOs in narrow ranges are easier, and a 4.0 MHz sine
> >>> source and 4.030 to 4.100 MHz sine VCO can be mixed down to get you
> >>> what you want.
> >> Ah, good. =A0This was my first suggestion on how to get what was wante=
d.
> >> It was rejected. =A0But perhaps I should push it a bit more!
>
> > It's what I'd push, if I couldn't convince people to use a DDS or if
> > there were some overriding systems reason why a DDS wouldn't do. ...
>
> I'll second that. Maybe we should make some signs and start a virtual
> picket line. Need a nice chant though. "Rah-rah-rah, os-ci-llate,
> down-con-vert, rah-rah-rah". Oh, and drums, of course :-)

Can I get some scantily clad drum majorettes too?  :^)

Seriously walking about last evening, I think this is the way to go!
We'll do heterodyning and VCO side band generation.  I'll order some
varactor diodes and build some LC tank ciruit.  Got a favorite
oscillator circuit?
Or should I get something ready to run?

Now I just have to convince the 'powers that be'.

George H.


>
> [...]
>
> --
> Regards, Joerg
>
> http://www.analogconsultants.com/- Hide quoted text -
>
> - Show quoted text -

On Sep 27, 6:27=A0pm, John S <soph...@invalid.org> wrote:
> On 9/27/2011 3:43 PM, Tim Wescott wrote:
>
>
>
> > The nonlinearity that you're battling isn't the diode conduction -- it'=
s
> > the diode's varying capacitance as its reverse voltage changes. =A0It's
> > going to be severe at low voltage/high capacitance. =A0I'm _not_ the
> > world's smartest SPICE guy, but I do know (more or less) that you want =
to
> > simulate the varactor with a really large-area diode. =A0I _think_ that
> > there's an area parameter that you can dink with, if you copy a diode
> > model out of the LTSpice library and paste it into your schematic. =A0O=
r go
> > out on the World of the Wide Web and find a varactor model.
>
> > I'm thinking that if you want to avoid seeing major distortion you want
> > to have the AC voltage be more like tens of millivolts, which will leav=
e
> > you open to noise problems.
>
> Tim -
>
> I agree. I do not know how to dink with a diode parameter, but I managed
> to make a device to simulate a VVC in LTSpice. I no longer have that
> file, but I remember using either an arbitrary function generator or a
> voltage controlled current to simulate a VVC. It was then that I saw the
> sine distortion.
>
> Sorry I don't have specifics.

No problem,  I was thinking that if I reversed the DC voltage across
one of the vari-caps then during the amplitude max of the sine wave
one vari-cap would be going up and the other down...that might help
reduce the distortion.  It'll be a fun circuit to play with.. and I'll
use the vari-caps in a real LC oscillator.

George H.

On 09/28/2011 09:26 AM, George Herold wrote:
> On Sep 27, 6:27 pm, John S<soph...@invalid.org>  wrote:
>> On 9/27/2011 3:43 PM, Tim Wescott wrote:
>>
>>
>>
>>> The nonlinearity that you're battling isn't the diode conduction -- it's
>>> the diode's varying capacitance as its reverse voltage changes.  It's
>>> going to be severe at low voltage/high capacitance.  I'm _not_ the
>>> world's smartest SPICE guy, but I do know (more or less) that you want to
>>> simulate the varactor with a really large-area diode.  I _think_ that
>>> there's an area parameter that you can dink with, if you copy a diode
>>> model out of the LTSpice library and paste it into your schematic.  Or go
>>> out on the World of the Wide Web and find a varactor model.
>>
>>> I'm thinking that if you want to avoid seeing major distortion you want
>>> to have the AC voltage be more like tens of millivolts, which will leave
>>> you open to noise problems.
>>
>> Tim -
>>
>> I agree. I do not know how to dink with a diode parameter, but I managed
>> to make a device to simulate a VVC in LTSpice. I no longer have that
>> file, but I remember using either an arbitrary function generator or a
>> voltage controlled current to simulate a VVC. It was then that I saw the
>> sine distortion.
>>
>> Sorry I don't have specifics.
>
> No problem,  I was thinking that if I reversed the DC voltage across
> one of the vari-caps then during the amplitude max of the sine wave
> one vari-cap would be going up and the other down...that might help
> reduce the distortion.  It'll be a fun circuit to play with.. and I'll
> use the vari-caps in a real LC oscillator.
>
> George H.

Yup.  Varactors are often sold as CA or CC pairs, so you can put the 
bias on at the midpoint, via a choke or a resistor.  That cancels the 
even-order distortion products, which helps a lot.

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

On Sep 27, 10:06=A0pm, Phil Hobbs
<pcdhSpamMeSensel...@electrooptical.net> wrote:
> On 09/27/2011 02:17 PM, Tim Wescott wrote:
>
>
>
> > On Tue, 27 Sep 2011 09:54:36 -0700, George Herold wrote:
>
> >> 30kHz to 100kHz VCO with sine wave output.
>
> >> I know this has been covered before in previous threads.
>
> >> The obvious way to do this is a digital signal generator (DSG) IC with
> >> maybe an A-D to measure the voltage. =A0I=92ve not done much digital s=
tuff
> >> in a while, so this has a bit of a learning curve. =A0But if anyone ha=
s
> >> some good chips to look at or app notes then please do share. =A0I've =
been
> >> looking at IC's on Analogs web site, but there are a lot to choose fro=
m!
>
> >> I was also thinking I could do this with a ~20MHz varactor controlled
> >> VCO as a variable clock into a DSG chip. =A0This looks easier to my
> >> unsophisticated digital mind.
>
> >> Finally I offer the following, =A0a Wien bridge oscillator =A0with var=
actor
> >> diodes as the capacitors. =A0 =A0I was also thinking I could use crapp=
y Z5U
> >> ceramic caps instead of the varactors.
>
> > It'll be rough to get the high impedances and low voltage swings you ne=
ed
> > for the Wien bridge oscillator to work either with varactors or with a
> > suggestion that I've made previously of using JFETs as variable resisto=
rs.
>
> > So: a high frequency VCO to a DDS chip, or a fixed-frequency reference =
to
> > a DDS that you write a frequency to with a micro, or (if you are for so=
me
> > reason insisting on "analog only") a VCO feeding a mixer, beating again=
st
> > a crystal oscillator.
>
> > I'd look to the DDS solution, or see if
>
> you can make a suitable block
>
> > with a PIC or similar, a good DAC, and some code.
>
> You can still get low-nanofarad Y5V caps in small sizes, and those plus
> a boost converter are about the best things going right now for high
> kilohertz stuff. =A0All the MVAM-style varactors are long gone.

Yeah searching for varactor's lots of them were/ are OBSELETE.
sigh.

PIN photdiodes have C's that change by factors of 4 or 5.  But that
seems like a spendy solution.


>
> I'd probably be wanting to use a tri-wave oscillator with a sine shaper.
> =A0 (You don't have to use the crappy diode ones--you can use a tanh to
> roll over the peaks and then subtract a bit of the original sine, as we
> discussed a year or so back. =A0I posted a suggestion athttp://electroopt=
ical.net/www/sed/sed.html, but it's a much older
> technique.

Hmmm, Thanks Phil, I'd forgotten about that.  (I had no need for it at
the time.)  How do I get a tanh function out of a diff pair.  (Yeah,
I'll try google too.)

George H.
>
> 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 nethttp://electrooptical.net- Hide quoted tex=
t -
>
> - Show quoted text -

On Sep 28, 12:51=A0am, HardySpicer <gyansor...@gmail.com> wrote:
> On Sep 28, 5:54=A0am, George Herold <gher...@teachspin.com> wrote:
>
> > Finally I offer the following, =A0a Wien bridge oscillator =A0with
> > varactor diodes as the capacitors. =A0 =A0I was also thinking I could u=
se
>
> Victoriana!

Yeah but the steam punk crowd love our stuff.  So that's a feature,
and not a bug.

Optial pumping was on boing boing a few years ago.

http://boingboing.net/tag/steampunk/page/3

Teaching apparatus it's about 2/3 of the way dwon the page.

George H.

On Sep 28, 6:21=A0am, George Herold <gher...@teachspin.com> wrote:
> On Sep 27, 5:00=A0pm, Joerg <inva...@invalid.invalid> wrote:
>
>
>
>
>
> > Tim Wescott wrote:
> > > On Tue, 27 Sep 2011 13:18:06 -0700, George Herold wrote:
>
> > >> On Sep 27, 3:40 pm, whit3rd <whit...@gmail.com> wrote:
> > >>> On Tuesday, September 27, 2011 9:54:36 AM UTC-7, George Herold wrot=
e:
> > >>>> 30kHz to 100kHz VCO with sine wave output. I was also thinking I
> > >>>> could do this with a ~20MHz varactor controlled VCO as a variable
> > >>>> clock into a DSG chip. =A0This looks easier to my unsophisticated
> > >>>> digital mind.
> > >>> Workable, of course, but not exactly a VCO anymore... and there's t=
he
> > >>> Nyquist filtering to do afterward.
>
> > >>>> Finally I offer the following, =A0a Wien bridge oscillator =A0with
> > >>>> varactor diodes as the capacitors.
> > >>> Not a great choice, because the Wein bridge requires MATCHED
> > >>> capacitors, tuned together, for best performance. =A0 It can be don=
e with
> > >>> a few trimmers (probably easiest to trim the offset + gain of the
> > >>> control voltages). =A0Then, there's the level translation problem (=
the
> > >>> capacitors in a Wien bridge don't have one end grounded).
> > >> Hi Whit3rd,
> > >> Did you look at my schematic? =A0I seem to have it running in LTspic=
e.
> > >>> Good sinewave LC VCOs in narrow ranges are easier, and a 4.0 MHz si=
ne
> > >>> source and 4.030 to 4.100 MHz sine VCO can be mixed down to get you
> > >>> what you want.
> > >> Ah, good. =A0This was my first suggestion on how to get what was wan=
ted.
> > >> It was rejected. =A0But perhaps I should push it a bit more!
>
> > > It's what I'd push, if I couldn't convince people to use a DDS or if
> > > there were some overriding systems reason why a DDS wouldn't do. ...
>
> > I'll second that. Maybe we should make some signs and start a virtual
> > picket line. Need a nice chant though. "Rah-rah-rah, os-ci-llate,
> > down-con-vert, rah-rah-rah". Oh, and drums, of course :-)
>
> Can I get some scantily clad drum majorettes too? =A0:^)
>
> Seriously walking about last evening, I think this is the way to go!
> We'll do heterodyning and VCO side band generation. =A0I'll order some
> varactor diodes and build some LC tank ciruit. =A0Got a favorite
> oscillator circuit?
> Or should I get something ready to run?
>
> Now I just have to convince the 'powers that be'.
>
> George H.
>
>
>
>
>
> > [...]
>
> > --
> > Regards, Joerg
>
> >http://www.analogconsultants.com/-Hide quoted text -
>
> > - Show quoted text -- Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -

A couple of words of caution if you decide to go the down-converter
route.

I missed your final amplitude requirements, but I would caution you if
you decide to use the 602 part and require an output approaching 0dBm
or better.  This really is a low power part with a weak IIP3.

Even though you have a single tone at the input, over driving parts
such as these can cause funny distortion effects.

Re VCO:  I doubt very seriously that you could use a free running
VCO.  The damn thing will just be doing to much of the =93wautsi=94.  So
plan on lock=92d VCO.

I would recommend, as others have suggested, a DDS system.

You might consider getting an eval board from AD.  They use to pass
those things out like candy.  But in this economy, who knows.  The big
advantage of the eval board is that they come with control software
that can be run off the pc.

Hope this helps.

On Sep 28, 1:14=A0am, whit3rd <whit...@gmail.com> wrote:
> On Tuesday, September 27, 2011 1:18:06 PM UTC-7, George Herold wrote:
> > On Sep 27, 3:40=A0pm, whit3rd <whi...@gmail.com> wrote:
> > > On Tuesday, September 27, 2011 9:54:36 AM UTC-7, George Herold wrote:
> > > > 30kHz to 100kHz VCO with sine wave output.
> > > > Finally I offer the following, =A0a Wien bridge oscillator =A0with
> > > > varactor diodes as the capacitors.
>
> > > Not a great choice, because the Wein bridge requires MATCHED
> > > capacitors, tuned together, for best performance. =A0 It can be
> > > done with a few trimmers (probably easiest to trim the offset + gain
> > > of the control voltages). =A0Then, there's the level translation prob=
lem
> > > (the capacitors in a Wien bridge don't have one end grounded).
> > Did you look at my schematic? =A0I seem to have it running in LTspice.
>
> It looked OK, but (1) tuning voltage of =A00 to 30V is typical to get the
> full C range of a varicap (and that's gonna go outside most op amp tolera=
nce),
> and (2) the amplitude-stabilizing part of a Wien oscillator will
> get added in, presumably? =A0It has to oscillate at low V to keep the
> varicaps in their linear range, so they don't frequency-multiply.
> Varicap diodes are STILL diodes, they'll rectify if you let the signal
> get as big as the bias.

Thanks Whit3rd, For the tuning range I might have to move the circuit
'ground' around a bit.  But, i'm probably stuck once the once the
varactor C's get below 10pF or so... stray capacitance will eat up any
changes.

For gain control I just had back to back diodes and a series resistor
across the feed back R.

Here's the LTspice file,
Sorry about the LT1354, but I don't do much spicing and have problems
getting the right .include files.

If you change parameters and it has trouble starting then goose R2
lower a bit.

George H.

Version 4
SHEET 1 948 1108
WIRE 352 -16 288 -16
WIRE -16 16 -48 16
WIRE 288 16 288 -16
WIRE 288 16 112 16
WIRE 416 16 416 -16
WIRE 480 16 416 16
WIRE -48 48 -48 16
WIRE 288 48 288 16
WIRE 352 48 288 48
WIRE 416 48 416 16
WIRE -16 128 -16 16
WIRE 0 128 -16 128
WIRE 112 128 112 16
WIRE 112 128 80 128
WIRE 176 128 112 128
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WIRE 560 128 256 128
WIRE 720 128 560 128
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WIRE 720 240 192 240
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WIRE 624 400 608 400
WIRE 720 400 720 240
WIRE 720 400 704 400
WIRE -288 416 -288 400
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WIRE 112 448 112 368
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WIRE -48 496 -48 464
WIRE 288 512 224 512
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WIRE 624 560 544 560
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WIRE 96 624 96 528
WIRE 256 624 256 544
WIRE 256 624 96 624
WIRE 352 656 352 640
FLAG -288 304 +V
FLAG -176 416 0
FLAG -288 416 0
FLAG -176 304 -V
FLAG 32 368 0
FLAG -48 608 0
FLAG 512 304 0
FLAG 352 656 0
FLAG -48 48 0
FLAG 160 208 +V
FLAG 160 272 -V
SYMBOL voltage -288 304 R0
SYMATTR InstName V1
SYMATTR Value 15
SYMBOL voltage -176 304 R0
SYMATTR InstName V2
SYMATTR Value -15
SYMBOL res 272 112 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 10K
SYMBOL res 96 112 R90
WINDOW 0 0 56 VBottom 2
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SYMATTR InstName R2
SYMATTR Value 4.6K
SYMBOL res 304 352 R90
WINDOW 0 0 56 VBottom 2
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SYMATTR InstName R3
SYMATTR Value 100K
SYMBOL res 16 368 M180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R4
SYMATTR Value 100K
SYMBOL cap 192 352 R90
WINDOW 0 0 32 VBottom 2
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SYMATTR InstName C1
SYMATTR Value 20pF
SYMBOL cap -64 272 R0
SYMATTR InstName C2
SYMATTR Value 20pF
SYMBOL res 720 384 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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SYMATTR Value 10k
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SYMATTR Value 10k
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WINDOW 0 0 56 VBottom 2
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SYMATTR InstName R9
SYMATTR Value 10k
SYMBOL cap -64 496 R0
SYMATTR InstName C4
SYMATTR Value 10=B5f
SYMBOL res 112 448 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R10
SYMATTR Value 10
SYMBOL voltage 352 544 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
WINDOW 0 31 36 Left 2
SYMATTR InstName V3
SYMATTR Value 5
SYMBOL res 560 544 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R11
SYMATTR Value 10k
SYMBOL OPAMPS\\OPAMP 576 448 R180
SYMATTR InstName U1
SYMBOL OPAMPS\\OPAMP 352 432 R180
SYMATTR InstName U3
SYMBOL OPAMPS\\OPAMP 192 592 R180
SYMATTR InstName U4
SYMBOL Opamps\\LT1354 160 176 R0
SYMATTR InstName U2
SYMBOL diode 416 32 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D2
SYMBOL diode 352 0 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D4
SYMBOL res 576 0 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R5
SYMATTR Value 10K
SYMBOL diode -112 256 R0
SYMATTR InstName D5
SYMBOL diode 112 464 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D6
TEXT 168 784 Left 2 !.tran 0 10ms 0 5u startup
TEXT 512 752 Left 2 !.include opamp.sub