Driver to drive?

[Joel Koltner]

mike wrote:

Solar cell phone chargers are novelty items for those
who haven't done the math. For the six people in the world
who like to do extended wilderness camping on sunny days within range
of a cell tower with uninterrupted tweeting,
solar makes a lot of sense.

Also throw in people who enjoy spending weeks or months at a time on a
bicycle; there are actually some pretty interesting blogs out there from
people who rode across the U.S., updating their blogs every day or so,
and kept a solar charger around so they wouldn't have the hassle of
finding a free outlet.

In general I agree it's mostly a novelty product though. That
unfortunately means that often the quality if pretty iffy, which is
quite the drawback for those people who could really use it.

If you want to remove the battery from your phone
and charge it, there's usually protection built into that
battery. You still need to know EXACTLY what technology
is being used.
Just connecting to the terminals is not simple.

Ideally, no, but in practice, it often is quite simple: A lot of cheap
Chinese charger do precisely what you say, "just connecting the
terminals." I believe it "works" because they're quite conservative
with their charging cut-off point (e.g., always 3.6V, even though some
batteries are intended to go to 3.7V) and charging current and, as you
mention, the batteries themselves have overcharge, overcurrent, and
overtemperature protection built-in as well.

 

[Joel Koltner]

Winston wrote:

IIRC, lots of cheap house intercoms used speakers as microphones.

Yep. Many a toy "walkie-talkie" too.

 

[mike]

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? (0.15
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.

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. There are at least
two (distributed) capacitors involved.

An arc has high frequency components and significant propagation
distances are involved.

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.

Don't forget to account for the radiation.

Are we having fun yet?

 

[Don Y]

On 4/2/2012 3:15 PM, Winston wrote:

George Herold wrote:
On Mar 29, 8:57 am, Robert Macy<robert.a.m...@gmail.com> wrote:
On Mar 28, 3:07 pm, muhaned.2...@gmail.com wrote:

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

Pressure Sensor

Anyone ever tried using a speaker as detector?

IIRC, lots of cheap house intercoms used speakers as microphones.

I think the (toy) electronic "trap sets" essentially use speakers
as the transducers.

 

[mike]

On 3/29/2012 2:54 PM, muhaned alzedi wrote:

thank u for reply ,but i want sensor for(transfer the maniacal motion to electric ) like microphone .
YOu need to be clear about what you want.

A piezoelectric pressure sensor works at LOW frequencies and is probably
as good
as it gets for converting mechanical motion to electrical energy.

Google "energy harvesting". There's lots of work going on in that field.

Bottom line is that there's power in an acoustic wave. You can't get
any more
out than exists. And usually, it's a LOT less.

Exactly what are you trying to accomplish?

 

[Jamie]

muhaned alzedi wrote:

thank u for reply ,but i want sensor for(transfer the maniacal motion to electric ) like microphone .

If you want to use sound for motion detection, loop for Ultrasonic
sensors.

Jamie

 

[Jamie]

Robert Macy wrote:

On Mar 28, 3:07 pm, muhaned.2...@gmail.com wrote:

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


Pressure Sensor
It's very hard to know exactly what he needs, I almost think that maybe

he is looking for a VRS sensor.. Or a magnet attached to the moving
part and have it pass by a loop. Either one would generate some energy
while in motion.


Jamie

 

[George Herold]

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?  (0.15
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, (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.

 

[Sjouke Burry]

George Herold <gherold@teachspin.com> wrote in news:67f58e85-3ef8-42ba-
9b89-831e7c1c165b@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, (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.

 

[WoolyBully]

On Mon, 02 Apr 2012 23:43:21 GMT, nico@puntnl.niks (Nico Coesel) wrote:

Bob E. <bespoke@invalid.tv> wrote:

Looking for philips #0 bits, 4 mm or 1/4-inch hex drive, long. Like the one
used here:

http://www.youtube.com/watch?v=_4PGAbyJzCU

I can find the regular stubby (25 mm long) ones but nothing small diameter &
long like that guy is using.

Occasionally available in sets, but I'd like just individual or bulk quantity
of one size.

That sort of stuff is best found on Ebay.

I found one named after you.

http://tinyurl.com/7d6zrt6

 

[WoolyBully]

On Mon, 2 Apr 2012 15:21:15 -0700, Bob E. <bespoke@invalid.tv> wrote:

Looking for philips #0 bits, 4 mm or 1/4-inch hex drive, long. Like the one
used here:

http://www.youtube.com/watch?v=_4PGAbyJzCU

I can find the regular stubby (25 mm long) ones but nothing small diameter &
long like that guy is using.

Occasionally available in sets, but I'd like just individual or bulk quantity
of one size.

Thanks.

http://tinyurl.com/7d6zrt6

 

[Tech-electro]

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

 

[John Devereux]

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

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

Those trainers ("sneakers"?) with flashing lights on the heels have
something like that inside them. You can feel something moving about
inside if you shake them. I assume it is a magnet in a coil sort of
thing, although I suppose it could be piezo.

--

John Devereux

 

[Jan Panteltje]

On a sunny day (Thu, 29 Mar 2012 06:21:45 -0700 (PDT)) it happened George
Herold <gherold@teachspin.com> wrote in
<be914a5a-c6b2-4d3d-9508-376fba30495b@i2g2000vbv.googlegroups.com>:

On Mar 29, 8:57 am, Robert Macy <robert.a.m...@gmail.com> wrote:
On Mar 28, 3:07 pm, muhaned.2...@gmail.com wrote:

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

Pressure Sensor

Anyone ever tried using a speaker as detector?

George H.

Oh yes, and I even came across some ancient intercoms that used the speakers as mike
if you pressed the talk switch.

 

[Spehro Pefhany]

On Tue, 03 Apr 2012 08:47:22 +0100, the renowned John Devereux
<john@devereux.me.uk> wrote:

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

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

Those trainers ("sneakers"?) with flashing lights on the heels have
something like that inside them. You can feel something moving about
inside if you shake them. I assume it is a magnet in a coil sort of
thing, although I suppose it could be piezo.

Could be a ball rolling around and touching contacts (activating a
CMOS chip). That's how I'd do it if I had to do it for pennies.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[John Devereux]

Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> writes:

On Tue, 03 Apr 2012 08:47:22 +0100, the renowned John Devereux
john@devereux.me.uk> wrote:

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

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

Those trainers ("sneakers"?) with flashing lights on the heels have
something like that inside them. You can feel something moving about
inside if you shake them. I assume it is a magnet in a coil sort of
thing, although I suppose it could be piezo.

Could be a ball rolling around and touching contacts (activating a
CMOS chip). That's how I'd do it if I had to do it for pennies.

So there is a lithium coin cell in there too? On reflection that does
seem more likely.

My 19- month old has just got some new shoes with the lights. Perhaps I
should cut them open. Yes, I'm sure mum would appreciate the spirit of
scientific enquiry.

--

John Devereux

 

[Spehro Pefhany]

On Tue, 03 Apr 2012 12:36:02 +0100, the renowned John Devereux
<john@devereux.me.uk> wrote:

Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> writes:

On Tue, 03 Apr 2012 08:47:22 +0100, the renowned John Devereux
john@devereux.me.uk> wrote:

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

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

Those trainers ("sneakers"?) with flashing lights on the heels have
something like that inside them. You can feel something moving about
inside if you shake them. I assume it is a magnet in a coil sort of
thing, although I suppose it could be piezo.

Could be a ball rolling around and touching contacts (activating a
CMOS chip). That's how I'd do it if I had to do it for pennies.

So there is a lithium coin cell in there too? On reflection that does
seem more likely.

My 19- month old has just got some new shoes with the lights. Perhaps I
should cut them open. Yes, I'm sure mum would appreciate the spirit of
scientific enquiry.

Why actually _do_ something, when someone else has undoubtedly done it
and posted about it?

http://www.robotroom.com/Light-Up-Shoes-Vibration-Sensor.html

Okay, the vibration sensor is a mass-spring-contact assembly rather
than a ball, but the idea is the same.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[Baron]

George Herold Inscribed thus:

On Mar 29, 8:57 am, Robert Macy <robert.a.m...@gmail.com> wrote:
On Mar 28, 3:07 pm, muhaned.2...@gmail.com wrote:

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

Pressure Sensor

Anyone ever tried using a speaker as detector?

George H.

Yes ! I've used the small 2" speaker as an impact sensor.

--
Best Regards:
Baron.

 

[George Herold]

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, (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...
but then the E field build up again and another little arc gets rid of
a bit more charge?

George H.

 

[Charmed Snark]

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.