Circuit Maker <<questions>>

bogdan_borko · 6th August 2006, 08:41 PM

How to measure distortion in circuit maker 2000?
How to do Fourier analysis and measure harmonics in dB?

bogdan_borko · 6th August 2006, 08:59 PM

I hope you understood what i`m asking for...
I meant "Harmonic distortion".
thanks

Steven · 6th August 2006, 09:08 PM

Select Analog Mode in Simulation, then go to Analyses Setup (F8), enable Transient/Fourier analysis and click on that button. In Transient and Fourier Analysis Setup enable Fourier (check box). At this moment I have the default timing selected (5 cycles, 50 points per cycle). Use a sine generator in the circuit diagram as input, e.g. at 1 kHz. Probe the output, or any point in the circuit.
Default the fourier analysis shows a linear frequency scale as the X-axis and volts or amps on the Y-axis. Right click on the Y-axis to get a pop up where you can select Primary Y-axis with Magnitude in Decibels. Then adjust the scaling, normally in the left pane, to e.g. 20dB per division and adjust the offset to get the harmonics in the graph. Distortion is calculated from the ratio of the harmonics and the fundamental.

bogdan_borko · 6th August 2006, 09:29 PM

thanks a LOT!

What is a good result in these measurements?

bogdan_borko · 6th August 2006, 09:43 PM

this is not good...?
could you comment?

it is a push pull mosfet class a power follower I`m simulating... it has no feedback, classic source follower...

Steven · 6th August 2006, 10:01 PM

Your harmonics are more than 60 dB below the fundamental, so distortion is approximately 0.1%, not bad for an open loop design.

bogdan_borko · 7th August 2006, 09:49 AM

how did you calculated 0.1%?

sreten · 7th August 2006, 11:09 AM

Quote:

Originally posted by bogdan_borko
how did you calculated 0.1%?

Hi,

0.1% is a thousanth = 10 to the power - 3 x 20 = - 60dB.

From the graph 2nd and 3rd dominate so I'd say ~ 0.2%.

/sreten.

bogdan_borko · 7th August 2006, 12:10 PM

thanks a lot guys!

I`ve searched the forum but haven`t found much about
what harmonic affects the sound the most (I just now the 2nd harmonic is "good") and what harmonic should we look at when we design the amplifier...

ANy link will be helpfull.
thanx!

sreten · 7th August 2006, 12:17 PM

Hi,

wieght the harmonics thus for degradation :

(harmonic number)squared / 4.

so 2nd = same, 3rd = x 9/4, 4th = x 4, 5th = x 25/4, 6th = x 9, etc

For 1khz 20 khz = x 100 or + 20dB, higher harmonics cannot be ignored......

/sreten.

6th August 2006, 08:41 PM	#1
bogdan_borko diyAudio Member Join Date: Nov 2005 Location: serbia, zajecar	Circuit Maker <<questions>> How to measure distortion in circuit maker 2000? How to do Fourier analysis and measure harmonics in dB?

6th August 2006, 10:01 PM	#6
Steven diyAudio Member Join Date: Oct 2003 Location: The Netherlands	Your harmonics are more than 60 dB below the fundamental, so distortion is approximately 0.1%, not bad for an open loop design. __________________ The Analog Art shows no sign of yielding to the Dodo's fate. The emergence and maturation of monolithic processing finesse has perhaps lagged a bit behind the growth of the Binary Business. But whereas digital precision is forever bounded by bits, there is no limit excepting Universal Hiss to the ultimate accuracy and functional variety of simple analog circuits. - Barry Gilbert, 1973

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6th August 2006, 08:59 PM	#2
bogdan_borko diyAudio Member Join Date: Nov 2005 Location: serbia, zajecar	I hope you understood what i`m asking for... I meant "Harmonic distortion". thanks

6th August 2006, 09:29 PM	#4
bogdan_borko diyAudio Member Join Date: Nov 2005 Location: serbia, zajecar	thanks a LOT! What is a good result in these measurements?

7th August 2006, 09:49 AM	#7
bogdan_borko diyAudio Member Join Date: Nov 2005 Location: serbia, zajecar	how did you calculated 0.1%?

7th August 2006, 12:10 PM	#9
bogdan_borko diyAudio Member Join Date: Nov 2005 Location: serbia, zajecar	thanks a lot guys! I`ve searched the forum but haven`t found much about what harmonic affects the sound the most (I just now the 2nd harmonic is "good") and what harmonic should we look at when we design the amplifier... ANy link will be helpfull. thanx!

7th August 2006, 12:17 PM	#10
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, wieght the harmonics thus for degradation : (harmonic number)squared / 4. so 2nd = same, 3rd = x 9/4, 4th = x 4, 5th = x 25/4, 6th = x 9, etc For 1khz 20 khz = x 100 or + 20dB, higher harmonics cannot be ignored...... /sreten.

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