Low-distortion Audio-range Oscillator

Congratulations - the sterling performance of your 2722 finally returns! Here's the FFT of a 1Vrms 1kHz after an "extreme" notch treatment on the UPV. The signal was routed from the generator to the analyzer externally through a RG316 cable to simulate connection to a DUT and reveal any possible EMF/RFI weaknesses in the chain, With H2 and H3 both around -151dB, it looks OK to me.

WOW ! I think I am in love.

🙂


-RNM
 
RNMarsh,

I don't know if it's my browser that doesn't work properly on DiyA, but when people add pictures directly inside the post instead of using the attachment function, and when clicking on the picture it takes me to another page and it's frustrating going through many pictures forth and back.

1. The picture zoom in and out with one single mouse click without taking one to another web page.

It maybe your browser... i use google chrome and it works as you want... just click on the pic and it zooms to fill your screen. I use the Attachment feature on this DIY page.


THx-RNMarsh
 
It maybe your browser... i use google chrome and it works as you want... just click on the pic and it zooms to fill your screen. I use the Attachment feature on this DIY page.
THx-RNMarsh

That's strange, it's just that your pictures doesn't appear as attachments inside the attachment box at the bottom of your posts (See picture 3), instead they are spread inside the post message area where one writes the text, for most other people it works and I can click and zoom in.

Are you sure you use the Attachment Manager as in picture 1?
And when you click on it, it opens up another small window on top of your browser according to picture 2?

As one can see in picture 4, user ci11's attachments works perfectly fine for me.
http://www.diyaudio.com/forums/equi...n-audio-range-oscillator-114.html#post4936747
Do not use the "Insert Image" button or any other tools from above tool bar, see picture 5, and do not paste pictures directly into the post.

Regarding picture upload problems, go to the "Forum Problems" section, link:
http://www.diyaudio.com/forums/forum-problems/301793-uploaded-photos-how-post.html

Sorry for hijacking this thread but this annoying inconsistency has to be sorted out because it seems the DiyA BBS software handles peoples attachments differently for a few uploaders.
 

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That's strange, it's just that your pictures doesn't appear as attachments inside the attachment box at the bottom of your posts (See picture 3), instead they are spread inside the post message area where one writes the text, for most other people it works and I can click and zoom in.

I tried it your way also but get same result. What I do is take a photograph with a camera. I take the camera's memory card to my computer in another room and plug it into the computer memory port. I open it, select the picture from the memory card and place in on the 'desk top' computer screen. Then, in DIY, i select that picture off the screen with 'manage attachments' at top of message screen to the right of the smiley face. Up load it and then select it for display on the DIY forum message board.

Afterwards, I move the picture file... still on the Desk Top screen to a related folder for safe keeping. And, i can access it from other locations/remote - such as when i am in Asia. perhaps if everything was done with only one computer.... but I have one for testing and another for all other uses.

If I do a screen capture and save that.... I still have to get it into another computer for this forum and emails and other things. Wirelessly networked or moving to a memory stick and transferring... still with same results.

Or show me another fix/way. I find it a minor issue to open/close a new page to get back where you were. But if you can meet my needs and a better way, I'll try it.


THx-RNMarsh
 
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THx-RNMarsh

Richard that's alright, you did your best and I'm sorry for bugging you with this issue, I had a quick view at the HTML code behind a few pictures, some that works as should and some from other users with same issues as yours, and there seems to be some discrepancies behind the code, I can only suspect it may be some kind of a glitch behind the DiyA forum, I will try call the moderators attention on it.

All the best, m.
 
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It is annoying but you might be able to adjust your browser so they don't open on another tab.
There appears to be two methods that the Forum software attaches pics stored in their server.
Some open in the same page to allow reading of both pic and script. Some open a new page. Any typing inserted in the first page is lost when one returns to the originating page.
There does not seem to be any way for the reader to avoid this. It's how the pic is loaded in the first instance, that controls this dual behaviour.
But both of these Forum stored pics/info are far better than using a remote server that closes down access and loses all pics.
 
I have opened up a new post under the "Forum Problems" section regarding the picture attachment problem, and the link is: http://www.diyaudio.com/forums/foru...doesnt-get-properly-uploaded-attachments.html

Richard, I have an idea you could try out, download a portable version of another browser, a portable version does Not install anything on your machine and you can store the browser in your USB memory stick or whatever portable medium, and try upload one picture from that browser, the browser I suggest you try is Firefox and can be downloaded from the trusted web page below, they convert many popular SW's into portable ones.
Mozilla Firefox ESR, Portable Edition 45.6.0 (web browser) Released | PortableApps.com - Portable software for USB, portable and cloud drives
Firefox ESR = "Extended Support Release", is a corporate version of Firefox and a safer choice!

Go then to the other thread in the link I gave above and try post attach a picture there so we can get this thread back on track.

Thanks, m.
 
One suggestion for pictures. I always use PNG format for posting. It seems more web friendly with smaller files. My computers are all networked (I have 2 in the shop + a laptop). I usually use Win 10's Snipping tool and save as PNG on the local machine. I then copy over the network to the separate system I use for web surfing. It works quite well. For some things I need to use XP (the machines are all dual boot) and I have ultra VNC running on all of them so I can control from another system in a different room. Its involved but it all works quite well.
 
I'm looking forward to it.
I've been playing with this oscillator for a while, and here is the list of changes made so far:

  • The two 5532s replaced by 4562, TL071 by OPA627
  • The 0.047uF polyester caps in the SVO replaced by two matched 0.033uF Wima FKP2
  • The 3K3 resistors replaced by 5K/0.1% glass-encapsulated resistors. I don't know their origin but I know they were used in the precision strain gauge amplifiers made by a company I used to work for.
  • Removed the two 100R freq. adj. trimmers, the frequency is now adjusted by trimming R1
  • Added a 22K pot in front of D1/R12 for adjusting the output voltage
  • The FET is now MMBF4091 with the parallel resistor R4 reduced to 500R
  • R3 in the local NFB from the 1st integrator to the inverter is reduced from 147K to 133K
For illustration, I'm enclosing a spectrum obtained at the output voltage of 1Vrms, but please note that this is not the best result I've got - I'm not at home right now and the measurement with the lowest THD was made with another laptop. While the 2nd is the same in that plot (-130dB), the 3rd is at the level of -140dB in the lowest THD spectrum I measured.
The measurements were made with a MOTU Audio Express interface using the SpectrumLab S/W, the sampling rate was 48kHz, FFT length 512K, spectral window was -196dB FlatTop, and the number of FFT averages was 32.
Other artifacts in the spectrum are not due to the oscillator - they come from the SMPS powering the audio interface.

Hope this spares some time in modifying the oscillator.

Regards,
Braca

I finally got my two examples running. Stock they are disappointing given what they started with. The output is sensitive to the negative supply voltage and is too high, especially for 5532's. I get less than .01% but just with strong HD2 and HD3. The AGC level detector seems to be less than ideal and has significant harmonic energy at its output. My first trick was to try to lower the output by changing R12. I think the PCB may be mismarked because its responses more like R13. Lowering to 3V out did not reduce the harmonics significantly. The distortion trim has almost no identifiable effect.

I created a simulation (attached) to see what it happening. It seems the AGC output has enough harmonic ripple that its getting into the JFET and causing the distortion. I'm still not sure what the real contribution of R3 and R10 is supposed to be. I made the simulation so i can try options easier, however even on a fast computer it takes a long time to run. With the stock values for C3 and C4 the output doesn't stabilise in 10 seconds which takes about 10 minutes to run. I reduced both 10X in the simulation pictures and increased R12 to 5 Meg to get the output down. It may be faster to just tweak the board itself.

The diodes listed are fast diodes but not really different from 1N914 and the transistor listed actually has a lower IDss with more C than the one I'm using in the simulation.

I'll play with it some more today.
 

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