wrote:
I am looking for an inexpensive (hopefully $20 or less) analog meter

one with a moving needle like this
http://en.wikipedia.org/wiki/Image:VU_Meter.jpg

that I can plug my computer's sound card into (actually two meters,
one for the right speaker, one for the left), that will read the pitch
of the audio being played.

I know that a given sound has a fundamental tone and overtones, and it
would have to detect the fundemantal tone (like a guitar tuner). The
audio source would be a MIDI program, so if necessary I could use
samples of a very simple waveform (ie Sine, square, etc) if that would
eliminate overtones and make pitch detection more accurate.

Does anyone know if such a meter exists or where to find plans to
build one?

Thanks.
If you have a computer anyway, how about using the sound input and run
one of the numerous spectrum analyser programs on it?

Wim

wrote:

I know that a given sound has a fundamental tone and overtones,
and it would have to detect the fundemantal tone (like a guitar tuner).

There's no need to "detect" the fundamental. The device would simply look
for zero crossings, which are the same regardless of the presence or absence
of harmonics.

In fact, I'm reasonably (but not completely) sure a PLL would work with a
non-sine signal.

National Semi still makes a "frequency to voltage" converter chip, so does
Analog.

But here's a link to using a PLL -- from National Semi -- Application Note
210
http://www.national.com/an/AN/AN-210.pdf

"jack" wrote in message
...

National Semi still makes a "frequency to voltage" converter chip,
so does Analog.

But here's a link to using a PLL -- from National Semi --
Application Note 210
http://www.national.com/an/AN/AN-210.pdf

This is fine, but what about the accuracy and resolution of the analog meter
used to read the output?

It still isn't clear why the OP is insisting on an analog display.

"jack" wrote ...
National Semi still makes a "frequency to voltage" converter
chip, so does Analog.

But here's a link to using a PLL -- from National Semi --
Application Note 210
http://www.national.com/an/AN/AN-210.pdf

Note that publication is 29 years old and I don't think any
of the mentioned ICs are still in production any more.

Richard Crowley wrote:

"jack" wrote ...

National Semi still makes a "frequency to voltage" converter chip, so
does Analog.

But here's a link to using a PLL -- from National Semi -- Application
Note 210
http://www.national.com/an/AN/AN-210.pdf


Note that publication is 29 years old and I don't think any
of the mentioned ICs are still in production any more.

Since when has that stopped real homebrewers? Ahh, I see a slew of cross-
posted groups (reading from r.r.a.h)

Michael

"msg" wrote ...
Richard Crowley wrote:
"jack" wrote ...

National Semi still makes a "frequency to voltage" converter chip,
so does Analog.

But here's a link to using a PLL -- from National Semi --
Application Note 210
http://www.national.com/an/AN/AN-210.pdf


Note that publication is 29 years old and I don't think any
of the mentioned ICs are still in production any more.

Since when has that stopped real homebrewers? Ahh, I see a slew of
cross-
posted groups (reading from r.r.a.h)

Don't get me wrong. I am working on a couple of projects
that could use circuits like that, but they are simply not
produciton-worthy anymore. :-(

In article
,
wrote:

I just want to do analog metering
with moving needle meters.

MS-

I once had an automotive tachometer that hooked between the engine's
points and ground, and was calibrated in RPM. I do not recall, but
there may have been separate scales for 6 and 8 cylinders.

I don't think it had any active components, and didn't require an
external power supply. It was measuring frequency by clipping,
differentiating the waveform and reading the integral of the pulse on a
sensitive meter movement. It was calibrated from a 60 Hz sine wave.

You may find something similar (or one with active circuits) if you
search for analog tachometer circuit on the web. If you have an old
automotive tachometer, just trace out its circuit.

Using it for higher audio frequencies should be a matter of calibration.

Fred

On Jan 7, 3:40 pm, Fred McKenzie wrote:

I once had an automotive tachometer that hooked between the engine's
points and ground, and was calibrated in RPM. I do not recall, but
there may have been separate scales for 6 and 8 cylinders.

The Mad Scientist still hasn't told us his application. Something like
that could work if he wanted to measure a stable frequency but it
would be of no use if he wanted to play music into it and have it
dance to the notes. '

There is no point to this discussion. If he doesn't want a frequency
meter for a single, continuous tone, he's barking up the wrong tree.
His meter won't provide a useful display no matter what.

"Fred McKenzie" wrote...
In article
,
wrote:

I just want to do analog metering
with moving needle meters.

MS-

I once had an automotive tachometer that hooked between the engine's
points and ground, and was calibrated in RPM. I do not recall, but
there may have been separate scales for 6 and 8 cylinders.

I don't think it had any active components, and didn't require an
external power supply. It was measuring frequency by clipping,
differentiating the waveform and reading the integral of the pulse on a
sensitive meter movement. It was calibrated from a 60 Hz sine wave.

You may find something similar (or one with active circuits) if you
search for analog tachometer circuit on the web. If you have an old
automotive tachometer, just trace out its circuit.

Using it for higher audio frequencies should be a matter of calibration.

If you differentiate the signal enough for the range of 20-20KHz,
you end up with an indication indistinguishable from "volume"! :-)
The request is fundamentally absurd.