Date: Tue, 20 Apr 2010 09:52:48

Author: George Herold

Subject: Re: Frequency/Function Generators

Post:

We bought a Protek function generator because it has fine resolution.
(sub milli-Hz out of 1 Hz) BUT, I was shocked to discover that at
higher frequency ranges the resolution was less... Maybe 0.1Hz. What
was troubling was that the front display said I was changing the
frequency.... But the real frequency never changed. Very distrubing.

GW Instek seems to make OK stuff. At least it does what it says.

George

-----Original Message-----
From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On
Behalf Of Zani, Gerald
Sent: Monday, April 19, 2010 12:38 PM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] Frequency/Function Generators

Cliff,

Strange, because the Pasco catalog shows the function generator with a
"41.613 Hz" reading.

But it has no fine tuning between frequency increments of 1 Hz?

What a drag!

My goodness!

Who was the genius to design that good feature. A 1 Hz resolution for a
general purpose frequency device?
Certainly it was made by someone who will never know what it means to
use it in an educational lab environment.

I am really disappointed. - J

-----Original Message-----
From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On
Behalf Of Cliff Bettis
Sent: Monday, April 19, 2010 12:27 PM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] Frequency/Function Generators

Jerry,

The newer Pasco Unit, the PI-8127, has discrete freq. adjustment of 1 Hz
steps in the kHz. Range. I don't like it for the shattering goblet
demonstration because of that.

Cliff

-----Original Message-----
From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On
Behalf Of Zani, Gerald
Sent: Monday, April 19, 2010 9:49 AM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] Frequency/Function Generators

The obsolete Pasco PI-9587C is an excellent function generator and is
what I've use for years to do the glass breaking demo w/o trouble.

I would first try the Pasco replacement model, the PI-8127. - Jerry



-----Original Message-----
From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On
Behalf Of Paul Nord
Sent: Monday, April 19, 2010 9:41 AM
To: tap-l@lists.ncsu.edu
Cc: Paul Nord
Subject: Re: [tap-l] Frequency/Function Generators

Zeke,

I've not done the glass breaking demo. But that looks like a reasonable
function generator.

Some of our older function generators have developed a problem with the
potentiometer that controls the frequency. They can be difficult to
adjust to a precise frequency. On some of the oldest ones I've been
able to replace the standard control with a 10-turn helipot to get very
fine control of the output.

The newer ones are all engineered very tightly into their cases which
makes changing a pot pretty difficult. But you could probably re-wire
the control to some external dial.

The electronics are not too difficult. You could probably build your
own from a kit:
http://www.electronickits.com/kit/complete/meas/fg500k.htm

If noise is a problem, you might try a bandpass filter.

Paul

On Apr 18, 2010, at 10:36 PM, Marc Zeke Kossover wrote:

> Howdy-
>
> I'm in the market for an audio frequency/function generator. (To run
an amp to break glass, if that matters.)
>
> I don't have a lot of money to spend, though, and can't afford the
sweet looking $600 models out there. Is there anything I can get for
less?
>
> For example, I used the frequency generator that is part of the Pasco
Passport but
it only displays to 0.1 Hz and has lots of distortion when amplified. I
think that the transient highs are frying my drivers.
>
> Alternately, I tried a computer based program, but it too only seemed
to display to 0.1 Hz and, I fear, floated a bit. It did however work
well enough to break window glass using the method from David Kardelis
.
>
> I saw this model on Ebay. Could it work?
>
> Marc "Zeke" Kossover
> The Jewish Community High School of the Bay
>
>
>






From tap-l-owner@lists.ncsu.edu Tue Apr 20 10:36:05 2010