What is a modern version of teh TBA120?

[Jan Panteltje]

What is a modern version of the TBA120?
Preferably in a package visible to the naked eye.

Actually I just need the limiting amp part from 1kHz to 20 MHz,
say 50 uV limiting in, couple of hundred mV limited out.
Supply voltage not important.
No noise.

[Jamie]

can't use a video amp? You could put some nice low cap diodes
in the feed back loop for limiting.

Jamie

[Jan Panteltje]

On a sunny day (Sat, 09 Feb 2013 15:31:20 GMT) it happened Jan Panteltje
<pNaonSt...@yahoo.com> wrote in <kf5q4f$mor$1...@news.albasani.net>:

>The other thing you could implement in software is a 'decrease increase' detector,
>and if you put a photocell outside perhaps a distance detector, variations are endless.

Or better an electret mike and measure the time delay between the RF spark and the sound.
I usually count, 3 seconds is a km.
A fast PIC could do a bit of digital signal processing to get that low rumble,
else some opamps..

[Michael A. Terrell]

Try that simplistic approach when the number of strikes is over 1100
in a half hour.

[Cydrome Leader]

Jan Panteltje <pNaonSt...@yahoo.com> wrote:
> On a sunny day (Sat, 09 Feb 2013 15:31:20 GMT) it happened Jan Panteltje
> <pNaonSt...@yahoo.com> wrote in <kf5q4f$mor$1...@news.albasani.net>:
>
>>The other thing you could implement in software is a 'decrease increase' detector,
>>and if you put a photocell outside perhaps a distance detector, variations are endless.
>
> Or better an electret mike and measure the time delay between the RF spark and the sound.
> I usually count, 3 seconds is a km.

Not trying to thread hijack here, but I've always wondered if the charge
onn the plastic in an electret mic fades away over time, like an old
magnet?

[gregz]

Makes you wonder. Mylar like tapes for wrapping have a charge. I once made
a Mylar tape electrostatic speaker.

Greg

[dave]

Magnets don't fade much. A little when they are young, but virtually
none after that.

[Silvar Beitel]

On Feb 12, 6:16 pm, Cydrome Leader <prese...@MUNGEpanix.com> wrote:

> Jan Panteltje <pNaonStpealm...@yahoo.com> wrote:
> > On a sunny day (Sat, 09 Feb 2013 15:31:20 GMT) it happened Jan Panteltje

> > <pNaonStpealm...@yahoo.com> wrote in <kf5q4f$mo...@news.albasani.net>:

>
> >>The other thing you could implement in software is a 'decrease increase' detector,
> >>and if you put a photocell outside perhaps a distance detector, variations are endless.
>
> > Or better an electret mike and measure the time delay between the RF spark and the sound.
> > I usually count, 3 seconds is a km.
>
> Not trying to thread hijack here, but I've always wondered if the charge
> onn the plastic in an electret mic fades away over time, like an old
> magnet?

This generally useful paper on electret microphones:

http://www.gentexcorp.com/assets/base/TechnicalPublications/ElectretAppGuideRev1.pdf

says "charge potential has a predicted half-life of several decades"

but doesn't describe the mechanism by which it is lost.

--
Silvar Beitel

[Michael A. Terrell]

They why do they need to remagnetize the magneto on old huff & puff
engines? I knew someone who made & sold hundreds of electromagnets for
that job.

[Bill Martin]

Perhaps they got too warm? I dunno!

[Phil Hobbs]

Iron and Alnico aren't stable the way ceramic and rare earth ones are.
If you leave the keeper off an Alnico magnet long, it'll demagnetize itself.

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

[dave]

On 02/13/2013 12:24 PM, Michael A. Terrell wrote:
>

Gosh. I don't know. Maybe too much huff and not enough puff.

Are permanent magnets really permanent?
Magnets generally retain their magnetism unless they are stored near
power lines, other magnets, and high temperatures. Over time, magnet
materials lose a very small amount of magnetism. For example, Samarium
Cobalt magnets may lose about 1% of their magnetism in ten years.

http://www.cmsmagnetics.com/basics.php#permanenthttp://www.cmsmagnetics.com/basics.php#permanen

[John Fields]

---
I've got a lot of Alnico bar magnets, and the way I keep them from
demagnetizing is to "69" them.

--
JF

[Michael A. Terrell]

Do you think that type of magnet was available when they designed
those first gasoline engines?

[dave]

Probably. I don't know. They may have compromised on the magnetic
properties for mechanical reasons. I researched it pretty thoroughly
when I was a loudspeaker contractor.

[Michael A. Terrell]

dave wrote:

>
> Michael A. Terrell wrote:
> >
> > Do you think that type of magnet was available when they designed
> > those first gasoline engines?
> >
>
> Probably. I don't know. They may have compromised on the magnetic
> properties for mechanical reasons. I researched it pretty thoroughly
> when I was a loudspeaker contractor.

They looked like Alnico magnets, and would die in about 20-50 years.
A speaker's magnetic circuit is nothing like a Magneto.


Huff & puff engines have been around for over 100 years, but Alnico
was developed in the '30s so it was probably just a cast iron slug that
was machined to have a smooth face.

[The Great Attractor]

On Wed, 13 Feb 2013 21:26:54 -0500, "Michael A. Terrell"
<mike.t...@earthlink.net> wrote:

>
>dave wrote:
>>
>> Michael A. Terrell wrote:
>> >
>> > Do you think that type of magnet was available when they designed
>> > those first gasoline engines?
>> >
>>
>> Probably. I don't know. They may have compromised on the magnetic
>> properties for mechanical reasons. I researched it pretty thoroughly
>> when I was a loudspeaker contractor.
>
>
> They looked like Alnico magnets, and would die in about 20-50 years.
>A speaker's magnetic circuit is nothing like a Magneto.
>

A lie. Antique generator sets still run just fine, and they were
fitted with AlNiCo magnets.

>
> Huff & puff engines have been around for over 100 years, but Alnico
>was developed in the '30s so it was probably just a cast iron slug that
>was machined to have a smooth face.

There were other magnet alloys before AlNiCo. It was probably NOT raw
Iron.

[Joseph Gwinn]

In article <kfeih2$n73$1...@reader1.panix.com>,

By imposing an electric field via the electrodes while the dielectric is
hot, and slowly cooling the electret material while maintaining the
polarizing voltage.

<http://en.wikipedia.org/wiki/Electret>

See the section on Manufacture.

Joe Gwinn

[Jan Panteltje]

74HC4046 is a good VCO.

If you need sinewave out, could a 4046 be used as clock for a DDS?
Never tried it.

Or even better: add a low-pass, makes a sinewave, leave out that DDS.

[Jan Panteltje]

And there is also some chip that does sinewave out, old modem chip,
2???, there are actually more.

[Joerg]

Jan Panteltje wrote:
> 74HC4046 is a good VCO.
>

I thought through that but no sine wave output.

Could have bet you'd come up with your standard answer "Use a PIC" :-)

> If you need sinewave out, could a 4046 be used as clock for a DDS?
> Never tried it.
>

Then I'd use a simple RC oscillator, it's smaller.

> Or even better: add a low-pass, makes a sinewave, leave out that DDS.
>

Can't do because range too wide. The range where the base frequency can
be set to.

> And there is also some chip that does sinewave out, old modem chip,
> 2???, there are actually more.
>

XR2206. Obsolete everywhere but as I posted yesterday I found a source
that sells those. Only as modules though but that's ok. It is in a
socket so I can get them out of there if needed.

--
Regards, Joerg

http://www.analogconsultants.com/