Any opinions or improvements suggestions about this low thd 1 khz sine generator ?

Status
Not open for further replies.
G

gaetan8888

New Member
Hello

Any opinions or improvements suggestions about this low thd 1 khz sine generator ?

Thank

Bye

Gaetan
 

Attachments

  • low thd 1 khz sine generator.JPG
    139.7 KB · Views: 171
gaetan8888 said:
Hello

Any opinions or improvements suggestions about this low thd 1 khz sine generator ?

Thank

Bye

Gaetan
Click to expand...

For what purpose do you need a 1khz Low THD sine wave generator?
Also, the 071 could use a 100pF cap across pins 1 and 8 (check the datasheet).
 
Such devices are as much 'art' as 'science', and I recall that it's easier to get low distortion using a bulb rather than an FET in the feedback - from HP I seem to remember?.
 
The key question is what is your spec for THD? -60 dB? -80dB? -100 dB?? then how will you verify it? If -60 dB, the solution to both could be a Software Sig Gen. and Spectrum Analyzer. Audacity.exe generate anything you can imagine and detect with AUX input.
 

Well that's not how you measure THD, it's in percentages (such as 0.01%) not dB's, and PC hardware is nowhere near capable of the requirements for decent quality audio measurements.

However, pretty cool thing Audacity - and would be VERY useful for less critical applications.
 
Nigel Goodwin said:
Well that's not how you measure THD, it's in percentages (such as 0.01%) not dB's, and PC hardware is nowhere near capable of the requirements for decent quality audio measurements.
Click to expand...
Yes of course, but Spectrum Analyzers measure in dB then you convert that to %THD . Last time I used an electret mic with tower Turtle sound card, I was surprised by the SNR and THD it recorded using Audacity. The mic also had a DC response with bias nulled. Let's see how much %THD is -120 dB for the waveform in memory.....
 
AnalogKid said:
Uhhh ... a dB is a ratio, as is a percentage.
Click to expand...

Except a percentage is in reference to a known point, a dB isn't - and regardless, you don't give distortion figures in dB - just as you don't give the weight of jewlery in metric tonnes.
 
AnalogKid said:
Uhhh ... a dB is a ratio, as is a percentage.

ak
Click to expand...

I've somehow avoided working with db to this point and recently confronted with a similar ratio question. This THD scenario frames it well.

If measuring THD, and there is a 10% positive and 10% negative deviation from the input signal, (i.e. output waveforms deviate from input from 90% to 110% of input), would THD be expressed as 0.9db (for the negative deviation) to 1.1db (positive deviation).
 
Last edited:
Nigel Goodwin said:
Except a percentage is in reference to a known point, a dB isn't - and regardless, you don't give distortion figures in dB - just as you don't give the weight of jewlery in metric tonnes.
Click to expand...
How can db be a ratio without a denominator?
 
Status
Not open for further replies.

Similar threads

B
  • Question
Morse generator
Replies
11
Views
2K
Reloadron
S
Varying Speed AC Generator to Steady DC
2 3
Replies
48
Views
5K
Soul21
S
B
  • Question
Sine to square wave conversion
2
Replies
27
Views
6K
bob4bvm
B
R
  • Question
Any potential problems with my diy home battery?
Replies
6
Views
3K
Diver300
D
S
Battery Charging using Variable speed generator
Replies
3
Views
1K
rjenkinsgb
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…