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-   -   Low Distortion Oscilator schematic anybody? (http://www.diyaudio.com/forums/solid-state/20021-low-distortion-oscilator-schematic-anybody.html)

tschrama 9th September 2003 02:55 PM

Low Distortion Oscilator schematic anybody?
 
Hi All,

I've done a search on this on the forum and indeed found some, but some values are missing or the link is dead. Maybe someone has got a nice little schematic for <0.01% oscilator, fixed frequency is OK.


Many greetings,

Thijs

tschrama 9th September 2003 03:54 PM

Come on guys, there must be plenty around.....

I found this one:

http://www.diyaudio.com/forums/showt...7435#post27435

Allthough the lamp is specified as 5W, I rather would like to now it's current rating ... does anyone know?

could I use a netwpork of 2 or 4 diodes/resistors instead to provide a non-linear resistance? Or would that yield high distortion?


Regards,
Thijs

hitsware 9th September 2003 04:05 PM

http://www.linear.com/prod/datasheet.html?datasheet=148

........here's another

peranders 9th September 2003 04:16 PM

Is 5 ppm (0.0005%) good enough? This wienbridge is rather complicated and needs a good pcb I imagine.
http://www.linear.com/prod/datasheet.html?datasheet=202

peranders 9th September 2003 04:19 PM

Re: Low Distortion Oscilator schematic anybody?
 
Quote:

Originally posted by tschrama
Hi All,

I've done a search on this on the forum and indeed found some, but some values are missing or the link is dead. Maybe someone has got a nice little schematic for <0.01% oscilator, fixed frequency is OK.

Have you considered an ordninary sound card?

My "junk" card gives 0.0087% distortion, Turtle Beach Santa Cruz.

Tone generator (excellent freeware): http://audio.rightmark.org I haven't checked if the software can produce sinus signals but I think so.

jackinnj 9th September 2003 04:44 PM

this idea appeared in AudioXpress -- you take a square wave generator (which can be a simple multivibrator type, xtal etc.) and pass the signal through 2 stages of filtering with the Linear Tech LT1063 low pass filters -- the distortion will be well below what you are looking for and the filter is very easy to tune

you just use a variety of counters to select the frequency

it helps if you have a "post filter" to remove the vestigial clocking noise from the circuit.

this won't get you a lot below 0.01%, but in the ballpark and without the need of ganged potentiometers, etc.

I have even experimented with this using the PicBasic Pro FREQOUT function on a 16F84 multiprocessor and gotten good results.

tschrama 9th September 2003 05:21 PM

Thanks .. got some reading to do :)


greetings,
Thijs

PMA 9th September 2003 05:38 PM

The Linear Technology circuits really work as they should ... ;)

tschrama 9th September 2003 05:53 PM

Hi everybody,

I just read the LT1037 opamp datahseet ...

The oscilator shown uses a #327 lamp ..... hmmmmmm I gues that means 5 Watt ;)

Can anybody give me some clues about what kind of lamp I need .. something like 12V / 200mA or more like 6V / 10mA?

Regards,
Thijs

PMA 9th September 2003 06:00 PM

I would follow the perander's link to low-distortion oscillator, as thinks start to happen near 0.001%, not 0.01% ..;) . Also have a look at LT1122 datasheet ..


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