Demo ideas

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So.

I have this effectively-infinitely-fast temperature control gizmo that  
I've been dying to make a good demo for. The gizmo produces a volume  
which is essentially immune to external thermal forcing, and that's what  
I want to demonstrate.  The idea would be to show what temperature does  
to some unprotected thing, then turn on the controller which will make  
it completely immune.

I'm thinking of building a sort of thermal Theremin with a crystal  
oscillator beating with an LC.  That ought to give a nice audible  
woo-woo sound when I heat it with a hair dryer or a small heat gun.   I  
might try dividing the XO down to 10 kHz or so and using a sample-hold  
to do the downconversion, so that the signal would never leave the audio  
range.

That will sound interesting, but might not be the most compelling demo.

Any alternatives?

(Sorry for the teaser--I'll happily say more about it when the patent  
has been filed.)

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
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Re: Demo ideas
On a sunny day (Sat, 9 Feb 2019 13:28:27 -0500) it happened Phil Hobbs

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Use your sensor or whatever it is to change the VCO input of a 4046
that runs in the audio range?
Offset voltage from sensor subtracted by opamp, some gain,
2 chips: opamp and 4046?

Or
digtal output from sensor to Linux PC running sgen,
any math you line in between.


Or
sensor voltage -> PIC ADC -> any math you like in asm -> PIC PWM -> audio amp..
or PIC PWM into small speaker:
 http://panteltje.com/panteltje/pic/audio_pic/

Or
NTC in 1 MHz oscillator, beat against medium wave broadcast station :-)  

Well the list of ways to do that is endless...

Re: Demo ideas
On Sat, 9 Feb 2019 13:28:27 -0500, Phil Hobbs

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What supports the isolated object?

I guess the oscillator could be battery powered and output its signal
magnetically or optically. Otherwise there would have to be lead wires
which would conduct heat. Or just suspend an LC tank that has a very
bad capacitor. I have some N4700s, but you can do much worse.

Hey, you're an optics guy: do something optical! Interference fringes
maybe.

Send us a link to the patent application after it's filed. Sounds
interesting.


--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: Demo ideas
On 2/9/19 1:46 PM, John Larkin wrote:
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I'm expecting it to be battery powered and just sit there on a table.  
The thermal conduction isn't a serious limitation as long as there's  
enough power available.

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I'm thinking about just using a ceramic cell phone speaker.  Doesn't  
have to be too loud.  Making it super temperature sensitive would be  
good--like some audible shift when you pass your hand over it without  
touching.

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That's an interesting idea, but it would have to be self-contained.  
Stabilized lasers, PCR reactors, sensors for road icing, and stuff like  
that are among the potential applications.

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Yeah, it's pretty fun.  I'll show you the demo sometime.  (It has an  
analogue square-rooter in the loop.)

Cheers

Phil Hobbs


--  
Dr Philip C D Hobbs
Principal Consultant
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Re: Demo ideas
On Sat, 9 Feb 2019 14:26:35 -0500, Phil Hobbs

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For a demo, I was thinking about parallel mirrors at the ends of a
little tube made out of something with a terrible expansion tempco,
plastic even. Shine a laser at it and change the temp and watch the
fringes squirm. Make a movie.

https://cdn.britannica.com/s:300x300/11/147311-004-613FB85F.jpg

That might be too intellectual for some of your prospects.



I'm busy Spicing a new pin driver; that circuit is sort of my lifetime
hobby. Just when I had a wonderful circuit, two critical parts (RF PNP
and big PHEMT) went EOL.


--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: Demo ideas
On 2/9/19 3:00 PM, John Larkin wrote:
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Yah, I know.  Broadcom and NXP have a lot to answer for.

Fortunately Mini-Circuits is trying to help, and Infineon still makes  
fast PNP arrays.

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
We've slightly trimmed the long signature. Click to see the full one.
Re: Demo ideas
On Sat, 9 Feb 2019 15:32:31 -0500, Phil Hobbs

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I've moved on with my life, to GaN and SiC. I wonder how long they
will last.


--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: Demo ideas
Phil Hobbs wrote...
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 I've made servos with square-root functions included.
 In one case I was servoing both a supply voltage and
 a PWM signal, that made the result go by the square
 of the servo output, so I added a square-root.  It
 worked very well, over three decades of linear output
 range.  (I didn't try removing the square root, to
 see how badly it'd do.)  BTW, analog multiplier ICs,
 to make the square root, are pretty scarce, and none
 work at the low voltages we like to use now.


--  
 Thanks,
    - Win

Re: Demo ideas
On 2/9/19 3:24 PM, Winfield Hill wrote:
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This one uses a power device, a dual BJT and a few resistors.  In the  
SPICE spherical-cow universe, it's +-5% of a real square root in the  
region of interest.

As long as the BJTs are at reasonably similar temperatures, the errors  
are mainly offsets, so the overall FB loop can compensate.

Cheers

Phil Hobbs


--  
Dr Philip C D Hobbs
Principal Consultant
We've slightly trimmed the long signature. Click to see the full one.
Re: Demo ideas
On Sunday, February 10, 2019 at 7:24:34 AM UTC+11, Winfield Hill wrote:
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 The Thaler THAT 2181 is a possible alternative to the Analog Devices AD734, and could be used at lower supply voltages - down to +/-4V

http://www.thatcorp.com/datashts/THAT_2181-Series_Datasheet.pdf

It's not touted as a multiplier but does seem to depend on a Gilbert cell.

--  
Bill Sloman

Re: Demo ideas
On 02/09/2019 09:31 PM, snipped-for-privacy@ieee.org wrote:
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There's a second source for them now via "CoolAudio" electronics in  
China, $3 each in small quantity:

<http://smallbear-electronics.mybigcommerce.com/ic-v2181l/

Re: Demo ideas

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Sounds ideal for controlling the temperature of the crystal in a reference  
oscillator. Such things are offered commercially, called an oven controlled  
crystal oscillator (OCXO). ppb frequency stability is obtainable.

The theory of such ovens was laid out by Richard Karlquist of HP, back in the  
day.

"THE THEORY OF ZERO-GRADIENT CRYSTAL OVENS", Richard Karlquist et al,  
and
Cutler, Karlquist, et. al, "High Thermal Gain Oven with Reduced Probability  
of Temperature Gradient Formation for the Operation of a Thermally Stable  
Oscillator," U. S. Patent 5,729,181.

Joe Gwinn


Re: Demo ideas
On Sat, 09 Feb 2019 16:27:32 -0500, Joseph Gwinn

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1998, back when HP still had something to do with electronics.



--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: Demo ideas
On Saturday, February 9, 2019 at 1:28:34 PM UTC-5, Phil Hobbs wrote:
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Huh, well my first thought for thermal control was a diode laser.  
As for a demo maybe an unequal arm Michelson, as the wavelength  
changes you can watch the nice fringe pattern change.  

Then lock your gizmo in and it stops changing...
(except for the thermal expansion of the optic table  
holding the interferometer.)

George H.  

  
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Re: Demo ideas
On 02/09/2019 01:28 PM, Phil Hobbs wrote:
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Yeah needs to be more dramatic.

Put some kind of thermally-activated triggering device in the volume  
that fires a huge volume of pink glitter and fart-scent spray around the  
conference room if it hits a certain temperature and put the whole  
apparatus on a hot plate with a dramatic RED 7-segment display like the  
show "24" showing the temperature rising to the critical temperature.

The attendees have to agree to sign off on a purchase order if their  
activating your device saves the day/their suits. Tell them it's a  
really nasty-smelling fart-spray, too, the worst there is. Lock the doors.



Re: Demo ideas
On 02/10/2019 12:25 AM, bitrex wrote:
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There are likely ways to tone this idea down a bit if fear of being  
arrested and/or deported but something in that vein would be good. Just  
brain-storming here.

Re: Demo ideas
On Saturday, February 9, 2019 at 10:28:34 AM UTC-8, Phil Hobbs wrote:
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If 'twere me, I'd say keep it simple: a hair dryer and a CO2 jet will make hot
and cold winds, and a thermistor (with a bridge to null and amplifier to gain-control)
can be made to swing a thermometer needle impressively.

Just apply heat for a second and watch the needle move.   Then apply cold.
Power the regulator and repeat.   It'd be best if the regulator activation was
graphically illustrated (big neon sign saying 'THERMOSTAT ENGAGED' would be nice).

Extra points for blue and red blower activator buttons, for icewater-based
coldside option, where everyone can see the ice.

Re: Demo ideas
On Saturday, February 9, 2019 at 10:28:34 AM UTC-8, Phil Hobbs wrote:
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  Most people are visual rather than auditory, so the suggestions using a v
isual display are good (the digital "24" display is a bit over the top, may
be).

  You can play to your audience- what are they interested in protecting? If
 electronics, one of their products would be good with whatever display or  
readout or other indication of out-of-range failure is appropriate. Keep th
e circuitry as obvious and transparent as possible to eliminate suspicions  
of fakery of course.

  Speaking of that you could demonstrate on something pretty much anyone ca
n look at and recognize, something not electronics-related.

  You could go with protecting raw egg white from denaturing if you can get
 past the obvious spoilage and potential health risks of such a demonstrati
on (in other words have someplace to dispose of the unprotected mess), but  
cracking and egg and separating out the whites while delivering your spiel  
is a great convincer of geniuneness.

  If you do that they will naturally ask about the potential range of opera
tion- what is that range, anyway? Can you use gallium alloys or other "exot
ic" materials to demonstrate the high/low ends without suspicion of fakery  
either accidental of intentional?

  I mention fakery not because I suspect you, but because something like yo
ur idea will be a hard sell and people not intimately familiar with the kin
d of electronic stuff we are will see it as "magic" and need some more basi
c convincing.


  Mark L. Fergerson

Re: Demo ideas
On Sat, 9 Feb 2019 22:51:03 -0800 (PST), " snipped-for-privacy@bid.nes"

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How about a tiny battery-powered device with LEDs that change color
dramatically over a small temp range? That would be fun.

Sort of AC couple it.



--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: Demo ideas
On 02/10/2019 01:51 AM, snipped-for-privacy@bid.nes wrote:
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Oh c'mon can't we have a stink-bomb demo pleeeaseee...

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