Driver to drive?

On Tue, 3 Apr 2012 14:48:41 +0000 (UTC), Charmed Snark
<snark@cogeco.ca> wrote:

Are you:

- looking to generate _power_ ?
- or to use the mic to _sense_ movement?

If you are looking for _power_ from a microphone, then I believe you're
barking up the wrong tree. Here's why:

One other way of analyzing things is to calculate the available
acoustic power.

At the threshold of pain, at 120 dB SPL, the acoustic power density is
1 W/m˛. A 110 mm diameter speaker cone will have a surface area of
about 1 dm˛, thus it would be subjected to 10 mW of acoustic power.

If the noise level is dropped to 80 dB, which is assumed to be safe
for constant exposure, the available acoustic power drops to 1 uW.

A speaker electricity to sound efficiency is typically below 1 %, so I
guess it also as bad in the other direction, thus perhaps 10 nW would
be available.

Of course you could use some exponential horn for a limited frequency
range to get a higher efficiency and also collect sound from a larger
area .

 

[mike]

On 4/3/2012 6:28 AM, George Herold wrote:

On Apr 2, 9:49 pm, Sjouke Burry<s@b> wrote:
George Herold<gher...@teachspin.com> wrote in news:67f58e85-3ef8-42ba-
9b89-831e7c1c1...@n19g2000yqk.googlegroups.com:







On Apr 2, 6:36 pm, mike<spam...@gmail.com> wrote:
On 3/28/2012 3:29 PM, George Herold wrote:

So this question comes the physics lab guys. Say you are uncharged
and ungrounded and touch a Van de Graaff (VdG) generator at say,
100kV. (Radius of VdG dome = 10cm.) What is the discharge time
and
average current.
More specifically can you take the human body model C (~100pF) and
R(~1.5k Ohm) and define the RC human charging discharging time?
(0.1
5
us)

Then does anything change if you happen to be grounded.

Thanks,

George H.

There is a thing called the human body model that is a first-order
approximation to the very much more complex situation of a distributed
resistor with some charge distributed over it.
Some standards organization chose R and C such that electrostatic
damage to some classes of electronic circuits was equivalent.

Yeah I picture this net of 1 k ohm resistors and a bunch of little C's

And that's just the load side.

A Van de Graff generator is a charged capacitor with a voltage-
dependent
charge transfer method trying to put more charge on it.
I guess I just ignored the charging of the Van de Graaff (VdG) during
the discharge.

There are at least
two (distributed) capacitors involved.

An arc has high frequency components and significant propagation
distances are involved.
Well I was hoping the arc would just look like some small resistor.
(And I could pretty much ignore it.)

So, you need much more information to predict the result.
Or you could just define a case and measure it.

And yes, everything changes if you happen to be grounded...
assuming you can define what grounded means for a distributed
system that's large relative to the wavelengths involved
with the discharge.

Well, Since my capacitance is a lot bigger than the VdG,

Take your DVM probes. Place them about an inch apart and grab
the pair with your thumb and forefinger. What resistance do you
measure?
Add that resistance to your model in series with your "bigger" body
capacitance.
How does that affect the transient response of your model.
(I'm assuming

a small dome), most of the charge is going to transfer to me whether
I'm grounded or not.

Don't forget to account for the radiation.

Are we having fun yet?

I tried charging myself up (rubbing me butt on the seat cushion) and
then discharging through a 100 ohm resistor attached across a x10
scope probe. The results were not very consistent. I did get some
decays with about a 1us time constant. But I think it's hard to grab
the end of the resistor consistently. Sometimes I'd see all these
short (~100ns) spiky things. miny arcs?

George H.

For a short time you were part of a sparc transmittor, the HF oscillation
causing short currrent bursts.- Hide quoted text -

- Show quoted text -

Oh, that's more fun than just a straight discharge. Do you think it's
a relaxation oscillation. A quick discharge of part of my charge, but
my body R can't get the charge there fast enough so the arc stops...
Think about that big resistor.
but then the E field build up again and another little arc gets rid of
a bit more charge?

George H.

Let's go back to the start.
Why do you care?
What problem are you trying to solve?
Do you not care about the peak currents and transient phenomena?

 

[linnix]

On Apr 2, 2:43 pm, hamilton <hamil...@nothere.com> wrote:

On 3/29/2012 1:26 AM, Klaus Kragelund wrote:







On 28 Mar., 22:01, Klaus Kragelund<klausk...@hotmail.com>  wrote:
On 28 Mar., 19:10, linnix<m...@linnix.info-for.us>  wrote:

On Mar 28, 2:55 am, Klaus Kragelund<klausk...@hotmail.com>  wrote:

Hi

For a new design I am looking for cheap LCD modules:

64x64 dots (or more)
16mm x 20mm outline
SPI, I2C, parallel, I don't care
Backlight

The source must be stable, so we don't run into obsolescence problems

Anyone come accross something below 3-5 USD in large quantities?

How large?  If in Ks, we can make them  Contact us at linnix at live
dot com.

I have just send you an email, thanks - Skjul tekst i anfřrselstegn -

- Vis tekst i anfřrselstegn -

For others that may be curious, found this:

http://dk.mouser.com/ProductDetail/Varitronix/COG-C144MVGI-08/?qs=sGA....

Good quality and seems it should sell for about 3 USD
Regards

Klaus

As per this link, 3 EURO != 3 USD

It is also a bit bigger than he wants, and without backlight. Anyway,
for small LCD this size, only graphical (segmented) screen make
sense. Otherwise, over 1/4 of non-viewable area or additional FPC ($$
$).

To OP: I emailed you back, but no response from you yet.

 

[spamtrap1888]

On Apr 2, 2:43 pm, hamilton <hamil...@nothere.com> wrote:

On 3/29/2012 1:26 AM, Klaus Kragelund wrote:







On 28 Mar., 22:01, Klaus Kragelund<klausk...@hotmail.com>  wrote:
On 28 Mar., 19:10, linnix<m...@linnix.info-for.us>  wrote:

On Mar 28, 2:55 am, Klaus Kragelund<klausk...@hotmail.com>  wrote:

Hi

For a new design I am looking for cheap LCD modules:

64x64 dots (or more)
16mm x 20mm outline
SPI, I2C, parallel, I don't care
Backlight

The source must be stable, so we don't run into obsolescence problems

Anyone come accross something below 3-5 USD in large quantities?

How large?  If in Ks, we can make them  Contact us at linnix at live
dot com.

I have just send you an email, thanks - Skjul tekst i anfřrselstegn -

- Vis tekst i anfřrselstegn -

For others that may be curious, found this:

http://dk.mouser.com/ProductDetail/Varitronix/COG-C144MVGI-08/?qs=sGA....

Good quality and seems it should sell for about 3 USD

Regards



As per this link, 3 EURO != 3 USD

I used to blame Bush for this, so now I blame Obama.

 

[mike]

On 4/3/2012 1:07 PM, Tech-electro wrote:

بتاريخ الخميس، 29 مارس، 2012 UTC+3 1:07:12 ص، كتب Tech-electro:
i want the best microphone (for sensor) for the low frequency,,,, what is it name ?

thank u for anyone
i want to generate 5 volt by using the microphone or(acoustic sensor )
At some point, you're gonna have to read what people have told you and

figure out
that the smallest battery you can find will put out orders of magnitude
more POWER than your acoustic sensor. Even a "potato battery"
will give you more energy.
You can't get there from here.

 

[Tech-electro]

بتاريخ الخميس، 29 مارس، 2012 UTC+3 1:07:12 ص، كتب Tech-electro:

i want the best microphone (for sensor) for the low frequency,,,, what is it name ?

thank u for anyone
i want to generate 5 volt by using the microphone or(acoustic sensor )

 

[Jamie]

Charmed Snark wrote:

Tech-electro expounded in
news:6615857.1182.1333425579087.JavaMail.geo-discussion-forums@vblo18:


the microphone use to transfer simple motion to electric , i want use
the microphone for generate 5 volt or more by amplifier circuit and
sorry for my language


It's still unclear to me what you want to do. You mention amplifier,
which is either not what you meant, or you're looking for something
completely different. Ignoring the word "amplifier"..

Are you:

- looking to generate _power_ ?
- or to use the mic to _sense_ movement?

If you are looking for _power_ from a microphone, then I believe you're
barking up the wrong tree. Here's why:

Consider:

- a dynamic mic has a low output voltage around 50 mV
- if 50mV appears across a 600 ohm input impedance, then
- current is only about 50mV/600 => 83 uA
- this is only giving you about 50mv x 83 uA => 4 uwatts!

This assumes you can get 50mV across 600 ohms-- mics are usually fed into
higher impedance inputs, so I am being optimistic here.

If you managed to convert that to 5 volts with 100% efficiency, you'd
arrive at a power supply of 5 volts, with an approximate current
capability of:

4 uwatts/5 volts => 0.8 uA (i.e. 0.0000008 Amp)

Does that still meet your goal??

You can do better with a crystal mic but then why restrict it to a
microphone, when all kinds of crystal transducers exist, which are
capable of producing more?

I don't believe we have the real "requirements" yet.

Warren.
if air current movement is all that is being looked for, then, the

simple mass air flow sensor I made with 0.005 bronze wire as the sensor
would work great..
That was so sensitive with a 6 foot center tapped wire that one could
stand ~ 10-15 feet away and blow just slightly through their lips and it
would react to it. Of course, that meant setting the threshold to a
critical point.

jamie

 

[gregz]

<muhaned.2012@gmail.com> wrote:

i want the best microphone (for sensor) for the low frequency,,,, what is it name ?

What frequency? Omnidirectional electret capsules will detect pressure
changes below 10 hz.

Greg

 

[WoolyBully]

On Tue, 3 Apr 2012 10:08:34 -0700, Bob E. <bespoke@invalid.tv> wrote:

I found one named after you.

http://tinyurl.com/7d6zrt6

No size #0.

Well, it isn't named after him then.

For size #0, take the #1 and cut off the tip and weld on the tip
portion of a #0 tip.

 

[Robert Macy]

On Apr 3, 3:13 pm, Jamie
<jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:

...snip...
if air current movement is all that is being looked for, then, the
simple mass air flow sensor I made with 0.005 bronze wire as the sensor
would work great..
   That was so sensitive with a 6 foot center tapped wire that one could
stand ~ 10-15 feet away and blow just slightly through their lips and it
would react to it. Of course, that meant setting the threshold to a
critical point.

  jamie

FASCINATING! Elaborate?

Where did you get 36 Awg bronze wire? What is the mechanism of
conversion from air mass movement to electrical signal? How accurate
must the center tap be? ....

 

[qrk]

On Tue, 3 Apr 2012 23:12:53 -0700, DaveC <invalid@invalid.net> wrote:

First of all, this is a request for a *recommendation*, not a request for
someone to do Google searches for me.
- - -
I need a charger for AA, AAA, and 9v batteries. Four of the AA or AAA
at a time is OK.

I see very few that support all these batteries (Maha makes a
separate charger for 9v). Of those that do, not all use delta-V
termination (or don't specify).

Of those remaining that qualify, I've not heard of the manufacturers
("Powerlzer"? -- that's not a misspelling), or Chinese no-name ones:

http://www.horizonbattery.com/battery-chargers/chargers-by-type/12-bay-aa-
aaa-9v-battery-charger.html

The Tenergy TN190 is the only one I've seen:

http://www.all-
battery.com/Tenergy_TN190_NiMH_NiCd_Advanced_Universal_Charger_with_LCD_Displa
y-01190.aspx

Does anybody know of such combo chargers? Can recommend one?

Thanks,
Dave

Maha chargers are recommended by many.

 

[Klaus Kragelund]

On 2 Apr., 23:43, hamilton <hamil...@nothere.com> wrote:

On 3/29/2012 1:26 AM, Klaus Kragelund wrote:







On 28 Mar., 22:01, Klaus Kragelund<klausk...@hotmail.com>  wrote:
On 28 Mar., 19:10, linnix<m...@linnix.info-for.us>  wrote:

On Mar 28, 2:55 am, Klaus Kragelund<klausk...@hotmail.com>  wrote:

Hi

For a new design I am looking for cheap LCD modules:

64x64 dots (or more)
16mm x 20mm outline
SPI, I2C, parallel, I don't care
Backlight

The source must be stable, so we don't run into obsolescence problems

Anyone come accross something below 3-5 USD in large quantities?

How large?  If in Ks, we can make them  Contact us at linnix at live
dot com.

I have just send you an email, thanks - Skjul tekst i anfřrselstegn -

- Vis tekst i anfřrselstegn -

For others that may be curious, found this:

http://dk.mouser.com/ProductDetail/Varitronix/COG-C144MVGI-08/?qs=sGA....

Good quality and seems it should sell for about 3 USD

Regards

Klaus

As per this link, 3 EURO != 3 USD

3 EUR, yes, but normalt the price figures ón distributor pages are
approx. 40 % higher than the "real" qoutes from the manufactor. Thus
EUR = USD

Cheers

Klaus

 

[Klaus Kragelund]

On 3 Apr., 19:55, linnix <m...@linnix.info-for.us> wrote:

On Apr 2, 2:43 pm, hamilton <hamil...@nothere.com> wrote:









On 3/29/2012 1:26 AM, Klaus Kragelund wrote:

On 28 Mar., 22:01, Klaus Kragelund<klausk...@hotmail.com>  wrote:
On 28 Mar., 19:10, linnix<m...@linnix.info-for.us>  wrote:

On Mar 28, 2:55 am, Klaus Kragelund<klausk...@hotmail.com>  wrote:

Hi

For a new design I am looking for cheap LCD modules:

64x64 dots (or more)
16mm x 20mm outline
SPI, I2C, parallel, I don't care
Backlight

The source must be stable, so we don't run into obsolescence problems

Anyone come accross something below 3-5 USD in large quantities?

How large?  If in Ks, we can make them  Contact us at linnix at live
dot com.

I have just send you an email, thanks - Skjul tekst i anfřrselstegn -

- Vis tekst i anfřrselstegn -

For others that may be curious, found this:

http://dk.mouser.com/ProductDetail/Varitronix/COG-C144MVGI-08/?qs=sGA...

Good quality and seems it should sell for about 3 USD
Regards

Klaus

As per this link, 3 EURO != 3 USD

It is also a bit bigger than he wants, and without backlight.  Anyway,
for small LCD this size, only graphical (segmented) screen make
sense.  Otherwise, over 1/4 of non-viewable area or additional FPC ($$
$).

To OP: I emailed you back, but no response from you yet.

Just responded

 

[Tech-electro]

بتاريخ الخميس، 29 مارس، 2012 UTC+3 1:07:12 ص، كتب Tech-electro:

i want the best microphone (for sensor) for the low frequency,,,, what is it name ?

what is name this sensor?

 

[Jamie]

Robert Macy wrote:

On Apr 3, 3:13 pm, Jamie
jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:

...snip...
if air current movement is all that is being looked for, then, the
simple mass air flow sensor I made with 0.005 bronze wire as the sensor
would work great..
That was so sensitive with a 6 foot center tapped wire that one could
stand ~ 10-15 feet away and blow just slightly through their lips and it
would react to it. Of course, that meant setting the threshold to a
critical point.

jamie


FASCINATING! Elaborate?

Where did you get 36 Awg bronze wire? What is the mechanism of
conversion from air mass movement to electrical signal? How accurate
must the center tap be? ....

I have an advantage when it comes to getting the wire, I work at a
place where we make many cables, wires etc, products. Fine bronze wire
is just one of those components we use in braid. I just walked out and
grab some from stock

Any way, you can get it on small rolls from various places. We used a
comparator circuit. We just set a fixed reference that can be trimmed on
one input and a voltage divided reference via the bronze wire on the
other input.

If you place one half of the tapped, lets say the lower side in the
area of interest but not in the breeze way, it'll be able to be at the
ambient temperature as the top half. The top half will be exposed to
the expected air flow.

The top side of this voltage divider is connected to the (+) rail
where a small amount of current will be present and cause the wire to
heat up
just a little bit.

When the top wire cools due to air flow around it, the R value on the
top side will drop. This drop will of course cause more current and
force the lower side to heat up even more and raise in R at the same
time. So the effect works for you in both aspects.

In the end, you get a nice effect and it reacts very quickly.

Since comparators and op-amps have such a high gain to start with, it
does not take much to fully switch the state. One could clean it up a
bit with a little hysteresis added.

If you need a basic ASCII schematic I can plop one where.

Jamie

 

[miso]

http://www.amazon.com/La-Crosse-Technology-BC-9009-AlphaPower/dp/B00077AA5Q

With such a wide range of good AA/AAA chargers and a dearth of AA/AAA/9V
chargers, I might get a dedicated 9V charger just to take care of those...

Thanks,
Dave

If you go the dedicated 9V charger route, just buy Sayno ENELOOPs with

their charger and junk your old batteries. It is really hard to beat
this technology.

I refuse to buy anything that uses a 9V battery. I often decide between
similar products based on the battery. I pick the prdocut that uses AA
over AAA cell. There is nothing like AA cells. No matter where you go,
you can find AA cells.

 

[John Devereux]

Tech-electro <muhaned.2012@gmail.com> writes:

بتاريخ الخميس، 29 مارس، 2012 UTC+3 1:07:12 ص، كتب Tech-electro:
i want the best microphone (for sensor) for the low frequency,,,, what is it name ?

what is name this sensor?

Bob.

Bob is his name,



--

John Devereux

 

[Robert Macy]

On Apr 4, 7:15 pm, Jamie
<jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:

Robert Macy wrote:
On Apr 3, 3:13 pm, Jamie
jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:

...snip...
if air current movement is all that is being looked for, then, the
simple mass air flow sensor I made with 0.005 bronze wire as the sensor
would work great..
  That was so sensitive with a 6 foot center tapped wire that one could
stand ~ 10-15 feet away and blow just slightly through their lips and it
would react to it. Of course, that meant setting the threshold to a
critical point.

 jamie

FASCINATING!  Elaborate?

Where did you get 36 Awg bronze wire?  What is the mechanism of
conversion from air mass movement to electrical signal? How accurate
must the center tap be? ....

  I have an advantage when it comes to getting the wire, I work at a
place where we make many cables, wires etc, products. Fine bronze wire
is just one of those components we use in braid. I just walked out and
grab some from stock

  Any way, you can get it on small rolls from various places. We used a
comparator circuit. We just set a fixed reference that can be trimmed on
one input and a voltage divided reference via the bronze wire on the
other input.

  If you place one half of the tapped, lets say the lower side in the
area of interest but not in the breeze way, it'll be able to be at the
ambient temperature as the top half. The top half will be exposed to
the expected air flow.

  The top side of this voltage divider is connected to the (+) rail
where a small amount of current will be present and cause the wire to
heat up
just a little bit.

  When the top wire cools due to air flow around it, the R value on the
top side will drop. This drop will of course cause more current and
force the lower side to heat up even more and raise in R at the same
time.  So the effect works for you in both aspects.

  In the end, you get a nice effect and it reacts very quickly.

  Since comparators and op-amps have such a high gain to start with, it
does not take much to fully switch the state. One could clean it up a
bit with a little hysteresis added.

   If you need a basic ASCII schematic I can plop one where.

Jamie

EXCELLENT description. I never thought of running current through the
wire!

Is that an ASCII netlist? like PSpice .cir file?

If in LTspice, the .asc file is also ASCII, starts with line that says
version 4.

post here or send direclty to me


.....apologies to original poster for hijacking his original thread.

However, I still recommend to him to get a fast updating altimeter -
that is a low frequency microphone. Didn't say how low? I think it's
called a geophone, or something like that.

 

[Jim Thompson]

On Thu, 5 Apr 2012 05:52:39 -0700 (PDT), Robert Macy
<robert.a.macy@gmail.com> wrote:

On Apr 4, 7:15 pm, Jamie
jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:
Robert Macy wrote:
On Apr 3, 3:13 pm, Jamie
jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:

...snip...
if air current movement is all that is being looked for, then, the
simple mass air flow sensor I made with 0.005 bronze wire as the sensor
would work great..
  That was so sensitive with a 6 foot center tapped wire that one could
stand ~ 10-15 feet away and blow just slightly through their lips and it
would react to it. Of course, that meant setting the threshold to a
critical point.

 jamie

FASCINATING!  Elaborate?

Where did you get 36 Awg bronze wire?  What is the mechanism of
conversion from air mass movement to electrical signal? How accurate
must the center tap be? ....

  I have an advantage when it comes to getting the wire, I work at a
place where we make many cables, wires etc, products. Fine bronze wire
is just one of those components we use in braid. I just walked out and
grab some from stock

  Any way, you can get it on small rolls from various places. We used a
comparator circuit. We just set a fixed reference that can be trimmed on
one input and a voltage divided reference via the bronze wire on the
other input.

  If you place one half of the tapped, lets say the lower side in the
area of interest but not in the breeze way, it'll be able to be at the
ambient temperature as the top half. The top half will be exposed to
the expected air flow.

  The top side of this voltage divider is connected to the (+) rail
where a small amount of current will be present and cause the wire to
heat up
just a little bit.

  When the top wire cools due to air flow around it, the R value on the
top side will drop. This drop will of course cause more current and
force the lower side to heat up even more and raise in R at the same
time.  So the effect works for you in both aspects.

  In the end, you get a nice effect and it reacts very quickly.

  Since comparators and op-amps have such a high gain to start with, it
does not take much to fully switch the state. One could clean it up a
bit with a little hysteresis added.

   If you need a basic ASCII schematic I can plop one where.

Jamie

EXCELLENT description. I never thought of running current through the
wire!

Is that an ASCII netlist? like PSpice .cir file?

If in LTspice, the .asc file is also ASCII, starts with line that says
version 4.

post here or send direclty to me


....apologies to original poster for hijacking his original thread.

However, I still recommend to him to get a fast updating altimeter -
that is a low frequency microphone. Didn't say how low? I think it's
called a geophone, or something like that.

For my Bachelor's thesis at MIT (in conjunction with Harvard Med
School) I used two very small thermistors on the end of a catheter,
one with current to heat it, one without, to measure blood flow in the
heart...

www.analog-innovations.com/BS_Thesis_JE_Thompson_1962.pdf

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Jim Thompson]

On Thu, 5 Apr 2012 09:39:53 -0700 (PDT), Robert Macy
<robert.a.macy@gmail.com> wrote:

On Apr 5, 9:00 am, Jim Thompson <To-Email-Use-The-Envelope-I...@On-My-
Web-Site.com> wrote:
On Thu, 5 Apr 2012 05:52:39 -0700 (PDT), Robert Macy





robert.a.m...@gmail.com> wrote:
On Apr 4, 7:15 pm, Jamie
jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:
Robert Macy wrote:
On Apr 3, 3:13 pm, Jamie
jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:

...snip...
if air current movement is all that is being looked for, then, the
simple mass air flow sensor I made with 0.005 bronze wire as the sensor
would work great..
  That was so sensitive with a 6 foot center tapped wire that one could
stand ~ 10-15 feet away and blow just slightly through their lips and it
would react to it. Of course, that meant setting the threshold to a
critical point.

 jamie

FASCINATING!  Elaborate?

Where did you get 36 Awg bronze wire?  What is the mechanism of
conversion from air mass movement to electrical signal? How accurate
must the center tap be? ....

  I have an advantage when it comes to getting the wire, I work at a
place where we make many cables, wires etc, products. Fine bronze wire
is just one of those components we use in braid. I just walked out and
grab some from stock

  Any way, you can get it on small rolls from various places. We used a
comparator circuit. We just set a fixed reference that can be trimmed on
one input and a voltage divided reference via the bronze wire on the
other input.

  If you place one half of the tapped, lets say the lower side in the
area of interest but not in the breeze way, it'll be able to be at the
ambient temperature as the top half. The top half will be exposed to
the expected air flow.

  The top side of this voltage divider is connected to the (+) rail
where a small amount of current will be present and cause the wire to
heat up
just a little bit.

  When the top wire cools due to air flow around it, the R value on the
top side will drop. This drop will of course cause more current and
force the lower side to heat up even more and raise in R at the same
time.  So the effect works for you in both aspects.

  In the end, you get a nice effect and it reacts very quickly.

  Since comparators and op-amps have such a high gain to start with, it
does not take much to fully switch the state. One could clean it up a
bit with a little hysteresis added.

   If you need a basic ASCII schematic I can plop one where.

Jamie

EXCELLENT description. I never thought of running current through the
wire!

Is that an ASCII netlist? like PSpice .cir file?

If in LTspice, the .asc file is also ASCII, starts with line that says
version 4.

post here or send direclty to me

....apologies to original poster for hijacking his original thread.

However, I still recommend to him to get a fast updating altimeter -
that is a low frequency microphone. Didn't say how low? I think it's
called a geophone, or something like that.

For my Bachelor's thesis at MIT (in conjunction with Harvard Med
School) I used two very small thermistors on the end of a catheter,
one with current to heat it, one without, to measure blood flow in the
heart...

       www.analog-innovations.com/BS_Thesis_JE_Thompson_1962.pdf

                                        ...Jim Thompson
[snip]

Isn't Doppler less intrusive?

(1) _50_ years ago.

(2) The doctor researchers were using it to evaluate _energy_ input to
the heart.

...Jim Thompson
--
| James E.Thompson, CTO | mens |
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I love to cook with wine. Sometimes I even put it in the food.