Magamp oscillator

[John Larkin]

On Fri, 06 Nov 2015 23:29:54 +0100, jeroen Belleman
<jeroen@nospam.please> wrote:

On 06/11/15 21:50, John Larkin wrote:
On Wed, 4 Nov 2015 08:55:37 +0000, piglet <erichpwagner@hotmail.com
wrote:

On 03/11/2015 10:45, Piotr Wyderski wrote:
Is it at all possible to build an oscillator entirely from
non-linear magnetics (OK, solid state diodes are allowed)?

Best regards, Piotr

There is such a thing as the "parametric transformer" about which I know
nothing but assuming it works like a varactor diode parametric amplifier
then I suppose it could be made to oscillate, I guess it needs a higher
frequency pump to provide the power source?

piglet

Right. Core saturation creates a nonlinear element that can do things,
but it needs an AC pump.

Here is a diode acting like a subharmonic oscillator. Same sort of
idea.

https://dl.dropboxusercontent.com/u/53724080/Circuits/Oscillators/SubHarmonic.jpg

Quick proof-of-concept hack. Could be optimized.

You brought this up some time ago when I asked about passive
circuits generating lower frequencies from a single higher input
frequency. (The equivalent of what a BBO crystal does with light.)

But this doesn't work. What you're really seeing in this circuit
is just the switch-on transient response of the tank, and which
dies out pretty quickly.

Jeroen Belleman

Well, I said it needs optimization. It should be possible to make this
work.

 

[jeroen Belleman]

On 07/11/15 17:02, John Larkin wrote:

On Fri, 06 Nov 2015 23:29:54 +0100, jeroen Belleman
jeroen@nospam.please> wrote:

On 06/11/15 21:50, John Larkin wrote:
On Wed, 4 Nov 2015 08:55:37 +0000, piglet <erichpwagner@hotmail.com
wrote:

On 03/11/2015 10:45, Piotr Wyderski wrote:
Is it at all possible to build an oscillator entirely from
non-linear magnetics (OK, solid state diodes are allowed)?

Best regards, Piotr

There is such a thing as the "parametric transformer" about which I know
nothing but assuming it works like a varactor diode parametric amplifier
then I suppose it could be made to oscillate, I guess it needs a higher
frequency pump to provide the power source?

piglet

Right. Core saturation creates a nonlinear element that can do things,
but it needs an AC pump.

Here is a diode acting like a subharmonic oscillator. Same sort of
idea.

https://dl.dropboxusercontent.com/u/53724080/Circuits/Oscillators/SubHarmonic.jpg

Quick proof-of-concept hack. Could be optimized.

You brought this up some time ago when I asked about passive
circuits generating lower frequencies from a single higher input
frequency. (The equivalent of what a BBO crystal does with light.)

But this doesn't work. What you're really seeing in this circuit
is just the switch-on transient response of the tank, and which
dies out pretty quickly.

Jeroen Belleman

Well, I said it needs optimization. It should be possible to make this
work.

Not with an ordinary Schottky diode it isn't. With a tunnel diode,
it should be possible.

Jeroen Belleman

 

[jeroen Belleman]

On 07/11/15 16:36, Phil Hobbs wrote:

On 11/06/2015 05:29 PM, jeroen Belleman wrote:
On 06/11/15 21:50, John Larkin wrote:
On Wed, 4 Nov 2015 08:55:37 +0000, piglet <erichpwagner@hotmail.com
wrote:

On 03/11/2015 10:45, Piotr Wyderski wrote:
Is it at all possible to build an oscillator entirely from
non-linear magnetics (OK, solid state diodes are allowed)?

Best regards, Piotr

There is such a thing as the "parametric transformer" about which I
know
nothing but assuming it works like a varactor diode parametric
amplifier
then I suppose it could be made to oscillate, I guess it needs a higher
frequency pump to provide the power source?

piglet

Right. Core saturation creates a nonlinear element that can do things,
but it needs an AC pump.

Here is a diode acting like a subharmonic oscillator. Same sort of
idea.

https://dl.dropboxusercontent.com/u/53724080/Circuits/Oscillators/SubHarmonic.jpg



Quick proof-of-concept hack. Could be optimized.

You brought this up some time ago when I asked about passive
circuits generating lower frequencies from a single higher input
frequency. (The equivalent of what a BBO crystal does with light.)

But this doesn't work. What you're really seeing in this circuit
is just the switch-on transient response of the tank, and which
dies out pretty quickly.

Jeroen Belleman

I don't understand your point. The waveform is periodic with twice the
period of the fundamental, but not at the fundamental frequency. How is
that not a subharmonic?

Degenerate parametric amps (pump = input) can also generate
subharmonics--you can buy packaged "frequency halvers" that just use
varactors. See e.g. http://tinyurl.com/p5kpgbj

Cheers

Phil Hobbs

It doesn't work. The observed double-period component is just the
tank ringing from the start-up transient. It doesn't last. Look
at the waveforms a bit later: There is no trace of a double-period
signal to be seen.

Jeroen Belleman

 

[John Larkin]

On Sun, 08 Nov 2015 23:23:33 +0100, jeroen Belleman
<jeroen@nospam.please> wrote:

On 07/11/15 17:02, John Larkin wrote:
On Fri, 06 Nov 2015 23:29:54 +0100, jeroen Belleman
jeroen@nospam.please> wrote:

On 06/11/15 21:50, John Larkin wrote:
On Wed, 4 Nov 2015 08:55:37 +0000, piglet <erichpwagner@hotmail.com
wrote:

On 03/11/2015 10:45, Piotr Wyderski wrote:
Is it at all possible to build an oscillator entirely from
non-linear magnetics (OK, solid state diodes are allowed)?

Best regards, Piotr

There is such a thing as the "parametric transformer" about which I know
nothing but assuming it works like a varactor diode parametric amplifier
then I suppose it could be made to oscillate, I guess it needs a higher
frequency pump to provide the power source?

piglet

Right. Core saturation creates a nonlinear element that can do things,
but it needs an AC pump.

Here is a diode acting like a subharmonic oscillator. Same sort of
idea.

https://dl.dropboxusercontent.com/u/53724080/Circuits/Oscillators/SubHarmonic.jpg

Quick proof-of-concept hack. Could be optimized.

You brought this up some time ago when I asked about passive
circuits generating lower frequencies from a single higher input
frequency. (The equivalent of what a BBO crystal does with light.)

But this doesn't work. What you're really seeing in this circuit
is just the switch-on transient response of the tank, and which
dies out pretty quickly.

Jeroen Belleman

Well, I said it needs optimization. It should be possible to make this
work.



Not with an ordinary Schottky diode it isn't. With a tunnel diode,
it should be possible.

Jeroen Belleman

Varicap diodes were once popular as microwave parametric amplifiers,
when other semiconductors were too slow.

https://en.wikipedia.org/wiki/Parametric_oscillator#Parametric_amplifiers

so I figure it can be a subharmonic oscillator, too.

https://en.wikipedia.org/wiki/Parametric_oscillator

 

[John Larkin]

On Sun, 08 Nov 2015 23:23:36 +0100, jeroen Belleman
<jeroen@nospam.please> wrote:

On 07/11/15 16:36, Phil Hobbs wrote:
On 11/06/2015 05:29 PM, jeroen Belleman wrote:
On 06/11/15 21:50, John Larkin wrote:
On Wed, 4 Nov 2015 08:55:37 +0000, piglet <erichpwagner@hotmail.com
wrote:

On 03/11/2015 10:45, Piotr Wyderski wrote:
Is it at all possible to build an oscillator entirely from
non-linear magnetics (OK, solid state diodes are allowed)?

Best regards, Piotr

There is such a thing as the "parametric transformer" about which I
know
nothing but assuming it works like a varactor diode parametric
amplifier
then I suppose it could be made to oscillate, I guess it needs a higher
frequency pump to provide the power source?

piglet

Right. Core saturation creates a nonlinear element that can do things,
but it needs an AC pump.

Here is a diode acting like a subharmonic oscillator. Same sort of
idea.

https://dl.dropboxusercontent.com/u/53724080/Circuits/Oscillators/SubHarmonic.jpg



Quick proof-of-concept hack. Could be optimized.

You brought this up some time ago when I asked about passive
circuits generating lower frequencies from a single higher input
frequency. (The equivalent of what a BBO crystal does with light.)

But this doesn't work. What you're really seeing in this circuit
is just the switch-on transient response of the tank, and which
dies out pretty quickly.

Jeroen Belleman

I don't understand your point. The waveform is periodic with twice the
period of the fundamental, but not at the fundamental frequency. How is
that not a subharmonic?

Degenerate parametric amps (pump = input) can also generate
subharmonics--you can buy packaged "frequency halvers" that just use
varactors. See e.g. http://tinyurl.com/p5kpgbj

Cheers

Phil Hobbs


It doesn't work. The observed double-period component is just the
tank ringing from the start-up transient. It doesn't last. Look
at the waveforms a bit later: There is no trace of a double-period
signal to be seen.

Jeroen Belleman

I think it will work if I get the values right.

 

[Phil Hobbs]

The paper I linked to (paywall unfortunately) talks about optimizing frequency halvers based on varactors and schottkys.

All you need is a nonlinear capacitance, which all diodes have, and low enough loss.

It should be possible to do it with a magamp too--it's a degenerate parametric oscillator.

Cheers

Phil Hobbs

 

[Tim Williams]

"Phil Hobbs" wrote in message
news:5b517d7f-dd73-4995-807d-400579d14441@googlegroups.com...

It should be possible to do it with a magamp too--it's a degenerate
parametric oscillator.

Does that mean a magamp oscillator would be expected to produce
frequencies of Fclk/N? Or, perhaps, *M/N for modest values thereof?

I know very little about parametric amps... All the explanations are
crap, which usually suggests that it's either a stupendously complex
subject, or a preposterously simple one (which is merely being presented
in a confusing manner as a barrier to entry, as many otherwise-simple
academic subjects tend to do).

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com

 

[John Larkin]

On Mon, 9 Nov 2015 12:59:46 -0600, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

"Phil Hobbs" wrote in message
news:5b517d7f-dd73-4995-807d-400579d14441@googlegroups.com...
It should be possible to do it with a magamp too--it's a degenerate
parametric oscillator.



Does that mean a magamp oscillator would be expected to produce
frequencies of Fclk/N? Or, perhaps, *M/N for modest values thereof?

I know very little about parametric amps... All the explanations are
crap, which usually suggests that it's either a stupendously complex
subject, or a preposterously simple one (which is merely being presented
in a confusing manner as a barrier to entry, as many otherwise-simple
academic subjects tend to do).

Tim

The simplest parametric amp is a variable capacitor connecting an RF
source to a resistive load. Change the cap and you can vary the load
power. It takes a tiny amount of energy to change the capacitance of a
mechanical variable cap or a varactor, so there is huge power gain.

Rectify the RF output back to DC, and you have a DC-controlled, DC
output amp with enormous power gain. But it needs the AC pump.

There are some simple graphical ways to look at my (currently not
working) parametric divider. And there is serious math, too.

There are varicap-based parametric amplifiers, mixers, dividers,
multipliers, and oscillators. Still used in microwave apps,
apparently.

It sounds like there was a telephone central-office 20 Hz ring
generator that was a magamp based divide-by-3, off the 60 Hz line.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[jeroen Belleman]

On 09/11/15 13:08, Phil Hobbs wrote:

The paper I linked to (paywall unfortunately) talks about optimizing
frequency halvers based on varactors and schottkys.

All you need is a nonlinear capacitance, which all diodes have, and
low enough loss.
[...]

OK, I give in. Here is a simple circuit that generates a strong and
persistent f/2 from an input at frequency f.

Jeroen Belleman

======== Cut here ========
Version 4
SHEET 1 880 680
WIRE 240 80 144 80
WIRE 288 80 240 80
WIRE 144 96 144 80
WIRE 288 128 288 80
WIRE 144 208 144 160
WIRE 144 208 96 208
WIRE 144 256 144 208
WIRE 288 272 288 208
WIRE 144 352 144 336
FLAG 288 272 0
FLAG 144 352 0
FLAG 240 80 tank
FLAG 96 208 pump
SYMBOL varactor 128 96 R0
SYMATTR InstName D1
SYMATTR Value MV2201
SYMBOL ind 272 112 R0
SYMATTR InstName L1
SYMATTR Value 1ďż˝
SYMBOL voltage 144 240 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value SINE(1 1 96.08meg)
TEXT 176 24 Left 2 !.tran 10u

 

[Phil Hobbs]

On 11/09/2015 01:59 PM, Tim Williams wrote:

"Phil Hobbs" wrote in message
news:5b517d7f-dd73-4995-807d-400579d14441@googlegroups.com...
It should be possible to do it with a magamp too--it's a degenerate
parametric oscillator.



Does that mean a magamp oscillator would be expected to produce
frequencies of Fclk/N? Or, perhaps, *M/N for modest values thereof?

I know very little about parametric amps... All the explanations are
crap, which usually suggests that it's either a stupendously complex
subject, or a preposterously simple one (which is merely being presented
in a confusing manner as a barrier to entry, as many otherwise-simple
academic subjects tend to do).

Tim

Arm waving explanation:

In an LC paramp, you want the capacitance to be decreasing as the
output goes through its +-peak values, and increasing at the zero
crossings. (A varactor wired across a bridge rectifier is one example
of a device that does this. Two varactors back-to-back also work.)

The voltage goes as 1/C, and the energy in the capacitor goes as CV**2,
so at the peaks

dE/dt = E/C dC/dt.

The circuit will oscillate at f/2 by building up from noise, provided
that the input is strong enough to make the loop gain at f/2 more than
unity. The output will be loosely phase locked with the input, of
course, because the gain isn't a very strong function of the relative phase.

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

 

[Tim Williams]

"Phil Hobbs" wrote in message
news:I7udnepF_KCguNzLnZ2dnUU7-aOdnZ2d@supernews.com...

Arm waving explanation:

In an LC paramp, you want the capacitance to be decreasing as the output
goes through its +-peak values, and increasing at the zero crossings. (A
varactor wired across a bridge rectifier is one example of a device that
does this. Two varactors back-to-back also work.)

The voltage goes as 1/C, and the energy in the capacitor goes as CV**2,
so at the peaks

dE/dt = E/C dC/dt.

The circuit will oscillate at f/2 by building up from noise, provided
that the input is strong enough to make the loop gain at f/2 more than
unity. The output will be loosely phase locked with the input, of
course, because the gain isn't a very strong function of the relative
phase.

How do you wire that? An L || C only has one resonant mode, and no
isolation. Would you use one resonator for the pump, one for the signal
frequency, and span the "funky C" between them? And then the signal
resonator then looks like a negative resistance, so you have to come up
with your own hybrid / isolator / circulator / etc. to get an amplifier as
such?

(The magamp equivalent would be two resonators, where the caps go to a
common ground, except it's not ground, it's the magamp core.)

How does one relate the impedances of such a circuit? The resonator
frequencies are defined by their LC components, plus the average
capacitance (more or less, and I suppose, give or take if the pump and
signal are correlated or not), and the pump magnitude is something about
the (Cmin / CJO) ratio and resonator impedances and Qs.

Does it only work at f/2? That seems rather less useful, needing an
oscillator at a much higher frequency all the time. (Of course, doublers
and triplers, of modest efficiency, are a thing. Often using varactors
again, it seems. But a stack of those gets rather wasteful.) After all,
magnetrons can be modulated, and that's old fashioned, like 10GHz in the
1950s, late 40s even. Though it's not like you can phase lock a magnetron
to a quartz oscillator (or better)...

I suppose that's the point, the pump can be any dirty old AC (give or take
"PSRR"), while the signal is something cleaner.

As for "degenerate", I presume that's something about being able to handle
DC (or most anything between DC and Fp/2)?

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com

 

[John Larkin]

On Mon, 09 Nov 2015 23:16:51 +0100, jeroen Belleman
<jeroen@nospam.please> wrote:

On 09/11/15 13:08, Phil Hobbs wrote:
The paper I linked to (paywall unfortunately) talks about optimizing
frequency halvers based on varactors and schottkys.

All you need is a nonlinear capacitance, which all diodes have, and
low enough loss.
[...]


OK, I give in. Here is a simple circuit that generates a strong and
persistent f/2 from an input at frequency f.

Jeroen Belleman

======== Cut here ========
Version 4
SHEET 1 880 680
WIRE 240 80 144 80
WIRE 288 80 240 80
WIRE 144 96 144 80
WIRE 288 128 288 80
WIRE 144 208 144 160
WIRE 144 208 96 208
WIRE 144 256 144 208
WIRE 288 272 288 208
WIRE 144 352 144 336
FLAG 288 272 0
FLAG 144 352 0
FLAG 240 80 tank
FLAG 96 208 pump
SYMBOL varactor 128 96 R0
SYMATTR InstName D1
SYMATTR Value MV2201
SYMBOL ind 272 112 R0
SYMATTR InstName L1
SYMATTR Value 1?
SYMBOL voltage 144 240 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value SINE(1 1 96.08meg)
TEXT 176 24 Left 2 !.tran 10u

Ooh, that's nice. The varicap is the nonlinear thing and the tank
capacitor simultaneously.

I had to change the L value to 1 uH; the "mu" symbol didn't survive
Usenet.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[piglet]

On 09/11/2015 20:30, John Larkin wrote:

It sounds like there was a telephone central-office 20 Hz ring
generator that was a magamp based divide-by-3, off the 60 Hz line.

Yes. The best known is possibly the Lorain Sub-cycler family:

<http://www.telephonecollectors.info/index.php/document-repository/cat_view/185-bruce-crawford-library/198-lorain-products>

The "decimonic" K5 produced 20Hz and 30Hz by para-amp action and then
mixed to generate 40Hz and 50Hz (10Hz spacing=decimonic) by a demonic
circuit shown in the download fig 8.

piglet

 

[Winfield Hill]

jeroen Belleman wrote...

On 09/11/15 13:08, Phil Hobbs wrote:
The paper I linked to (paywall unfortunately) talks about optimizing
frequency halvers based on varactors and schottkys.

All you need is a nonlinear capacitance, which all diodes have, and
low enough loss.
[...]


OK, I give in. Here is a simple circuit that generates a strong and
persistent f/2 from an input at frequency f.

Jeroen Belleman

======== Cut here ========
Version 4
SHEET 1 880 680
WIRE 240 80 144 80
WIRE 288 80 240 80
WIRE 144 96 144 80
WIRE 288 128 288 80
WIRE 144 208 144 160
WIRE 144 208 96 208
WIRE 144 256 144 208
WIRE 288 272 288 208
WIRE 144 352 144 336
FLAG 288 272 0
FLAG 144 352 0
FLAG 240 80 tank
FLAG 96 208 pump
SYMBOL varactor 128 96 R0
SYMATTR InstName D1
SYMATTR Value MV2201
SYMBOL ind 272 112 R0
SYMATTR InstName L1
SYMATTR Value 1ďż˝
SYMBOL voltage 144 240 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value SINE(1 1 96.08meg)
TEXT 176 24 Left 2 !.tran 10u

Is that LTSpice? It complains, Multiple instances of "Flag"


--
Thanks,
- Win

 

[Jeroen Belleman]

On 2015-11-10 14:14, Winfield Hill wrote:

jeroen Belleman wrote...

On 09/11/15 13:08, Phil Hobbs wrote:
The paper I linked to (paywall unfortunately) talks about optimizing
frequency halvers based on varactors and schottkys.

All you need is a nonlinear capacitance, which all diodes have, and
low enough loss.
[...]


OK, I give in. Here is a simple circuit that generates a strong and
persistent f/2 from an input at frequency f.

Jeroen Belleman

======== Cut here ========
Version 4
SHEET 1 880 680
WIRE 240 80 144 80
WIRE 288 80 240 80
WIRE 144 96 144 80
WIRE 288 128 288 80
WIRE 144 208 144 160
WIRE 144 208 96 208
WIRE 144 256 144 208
WIRE 288 272 288 208
WIRE 144 352 144 336
FLAG 288 272 0
FLAG 144 352 0
FLAG 240 80 tank
FLAG 96 208 pump
SYMBOL varactor 128 96 R0
SYMATTR InstName D1
SYMATTR Value MV2201
SYMBOL ind 272 112 R0
SYMATTR InstName L1
SYMATTR Value 1ďż˝
SYMBOL voltage 144 240 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value SINE(1 1 96.08meg)
TEXT 176 24 Left 2 !.tran 10u

Is that LTSpice? It complains, Multiple instances of "Flag"

Yes indeed. It doesn't complain here. OK, I declined to
upgrade LTspice since almost four years. Some asc file
format changes may have occurred since.

Beware of the value of L1: It should be 1uH. The 'mu'
doesn't fare well on Usenet. Sorry about that. I just
fix that using a text editor when it happens to me.

Here's an ASCII version of the schematic:

tank
+-----------+
| |
| |
V MV2201 L
= varicap L
| L 1u
| |
- |
/ \ |
| V | GND
\ /
| V=1+sine(97MHz) (pump)
|
GND

Next challenge: A circuit that produces two *different*
frequencies, such that f1+f2=fpump.

Jeroen Belleman

 

[John Larkin]

On 10 Nov 2015 05:14:54 -0800, Winfield Hill
<hill@rowland.harvard.edu> wrote:

jeroen Belleman wrote...

On 09/11/15 13:08, Phil Hobbs wrote:
The paper I linked to (paywall unfortunately) talks about optimizing
frequency halvers based on varactors and schottkys.

All you need is a nonlinear capacitance, which all diodes have, and
low enough loss.
[...]


OK, I give in. Here is a simple circuit that generates a strong and
persistent f/2 from an input at frequency f.

Jeroen Belleman

======== Cut here ========
Version 4
SHEET 1 880 680
WIRE 240 80 144 80
WIRE 288 80 240 80
WIRE 144 96 144 80
WIRE 288 128 288 80
WIRE 144 208 144 160
WIRE 144 208 96 208
WIRE 144 256 144 208
WIRE 288 272 288 208
WIRE 144 352 144 336
FLAG 288 272 0
FLAG 144 352 0
FLAG 240 80 tank
FLAG 96 208 pump
SYMBOL varactor 128 96 R0
SYMATTR InstName D1
SYMATTR Value MV2201
SYMBOL ind 272 112 R0
SYMATTR InstName L1
SYMATTR Value 1ďż˝
SYMBOL voltage 144 240 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value SINE(1 1 96.08meg)
TEXT 176 24 Left 2 !.tran 10u

Is that LTSpice? It complains, Multiple instances of "Flag"

I ran it in the current LT Spice, except that ? should be u.

It's amazing. Divides by 2 with gain!

 

[Tauno Voipio]

On 10.11.15 15:14, Winfield Hill wrote:

jeroen Belleman wrote...

On 09/11/15 13:08, Phil Hobbs wrote:
The paper I linked to (paywall unfortunately) talks about optimizing
frequency halvers based on varactors and schottkys.

All you need is a nonlinear capacitance, which all diodes have, and
low enough loss.
[...]


OK, I give in. Here is a simple circuit that generates a strong and
persistent f/2 from an input at frequency f.

Jeroen Belleman

======== Cut here ========
Version 4
SHEET 1 880 680
WIRE 240 80 144 80
WIRE 288 80 240 80
WIRE 144 96 144 80
WIRE 288 128 288 80
WIRE 144 208 144 160
WIRE 144 208 96 208
WIRE 144 256 144 208
WIRE 288 272 288 208
WIRE 144 352 144 336
FLAG 288 272 0
FLAG 144 352 0
FLAG 240 80 tank
FLAG 96 208 pump
SYMBOL varactor 128 96 R0
SYMATTR InstName D1
SYMATTR Value MV2201
SYMBOL ind 272 112 R0
SYMATTR InstName L1
SYMATTR Value 1ďż˝
SYMBOL voltage 144 240 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value SINE(1 1 96.08meg)
TEXT 176 24 Left 2 !.tran 10u

Is that LTSpice? It complains, Multiple instances of "Flag"

It works here in LTSpice, after correcting the value of L1 to 1u.

--

-TV

 

[legg]

On Mon, 09 Nov 2015 23:16:51 +0100, jeroen Belleman
<jeroen@nospam.please> wrote:

On 09/11/15 13:08, Phil Hobbs wrote:
The paper I linked to (paywall unfortunately) talks about optimizing
frequency halvers based on varactors and schottkys.

All you need is a nonlinear capacitance, which all diodes have, and
low enough loss.
[...]


OK, I give in. Here is a simple circuit that generates a strong and
persistent f/2 from an input at frequency f.

Jeroen Belleman

Check your source impedance/current. Is it a fair trade?

RL

 

[jeroen Belleman]

On 10/11/15 21:53, legg wrote:

On Mon, 09 Nov 2015 23:16:51 +0100, jeroen Belleman
jeroen@nospam.please> wrote:

On 09/11/15 13:08, Phil Hobbs wrote:
The paper I linked to (paywall unfortunately) talks about optimizing
frequency halvers based on varactors and schottkys.

All you need is a nonlinear capacitance, which all diodes have, and
low enough loss.
[...]


OK, I give in. Here is a simple circuit that generates a strong and
persistent f/2 from an input at frequency f.

Jeroen Belleman

Check your source impedance/current. Is it a fair trade?

RL

Not the point. The argument was about using parametric effects to
make oscillators.

Come to think of it, I posted about another such thing, in an
argument over using mains-frequency driven magnet coils to sustain
a pendulum swinging at a ~1s period. That was a parametric
oscillator too.

Jeroen Belleman

 

[John Larkin]

On Tue, 10 Nov 2015 21:46:10 -0500, krw <krw@nowhere.com> wrote:

On Tue, 10 Nov 2015 21:23:26 -0500, legg <legg@nospam.magma.ca> wrote:

On Tue, 10 Nov 2015 23:02:39 +0100, jeroen Belleman
jeroen@nospam.please> wrote:

On 10/11/15 21:53, legg wrote:
On Mon, 09 Nov 2015 23:16:51 +0100, jeroen Belleman
jeroen@nospam.please> wrote:

On 09/11/15 13:08, Phil Hobbs wrote:
The paper I linked to (paywall unfortunately) talks about optimizing
frequency halvers based on varactors and schottkys.

All you need is a nonlinear capacitance, which all diodes have, and
low enough loss.
[...]


OK, I give in. Here is a simple circuit that generates a strong and
persistent f/2 from an input at frequency f.

Jeroen Belleman

Check your source impedance/current. Is it a fair trade?

RL


Not the point. The argument was about using parametric effects to
make oscillators.

Come to think of it, I posted about another such thing, in an
argument over using mains-frequency driven magnet coils to sustain
a pendulum swinging at a ~1s period. That was a parametric
oscillator too.

Jeroen Belleman

It's not gain.

It's not an oscillator, either.

The 60 Hz pump trick adds energy to the resonant device, the pendulum,
just as a transistor (or a varicap pump) adds energy to an LC. Adding
energy keeps the oscillation from dying out.

A pumped resonator is an oscillator. As a bonus, the parametric
oscillator is phase-locked to the pump.