Building the Janascard Low Distortion Oscillator (Supply needed) - Page 1
Forum section: electronics / testgear

author: Martin72
author_rank: Super Contributor
timestamp: October 17, 2023, 07:49:59 pm
content: Hi,I have finished the Ultra-Low Distortion Oscillator (min -140dB) from janascard and successfully put it into operation.Now I want to give it a suitable supply, needed are +/-15V.Doesn't have to supply much current, so can be a constructionally small solution.The oscillator board itself is already well buffered, so doesn't need to be a super low noise story.Are there (partly) ready solutions beyond Alibaba LM78/7915 boards ?Man, no, I, am lazy by nature, otherwise I'll just have to sit down at the computer and construct one after all.Thanks for the tips in advance...EDIT: Title changed.

author: TimFox
author_rank: Super Contributor
timestamp: October 17, 2023, 09:02:42 pm
content: I have found unused Analog Devices modular power supplies (e.g., 902) on eBay.The ones I bought have 120 V input.Even though they were on the shelf for a while, the few I bought were in good working condition, with low ripple on the +/-15 V, 100 mA outputs.Another good source on eBay is Acopian.(Many eBay vendors can't read labels and list the Acopian units by fuse size, rather than output voltage/current.)

author: hpw
author_rank: Frequent Contributor
timestamp: October 18, 2023, 06:03:45 am
content: Quote from: Martin72 on October 17, 2023, 07:49:59 pmAs it comes to the ultimate LDO (low distortion oscillator), as -160dBc using Victors. Just visit the lengthy on DIYAUDIO.com "Equipment & Tools" forum.Important to shield the oscillator as in a box otherwise Hum to see as it goes for the Victor LDO...LDO as on DiyAudiohttps://www.diyaudio.com/community/threads/low-distortion-audio-range-oscillator.205304/page-499Some uses for the power batteries as low current use or some uses the SilentSwitcher as +/- 15V output (hard to get on those days), as from 5V or 12 batteries or USB power blocks.In addition, a Notch is required to mask the ADC THD's as getting the real THD of the LDO

author: Martin72
author_rank: Super Contributor
timestamp: October 18, 2023, 10:34:17 am
content: Hi,The LDO fromjanascardcomes with a notchfilter included.You can buy a complete assembled unit, only the populated pcbs or only the unpopulated pcbs, like I did.Description is here(pdf):http://www.janascard.cz/PDF/An%20ultra%20low%20distortion%20oscillator%20with%20THD%20below%20-140%20dB.pdfPic below shows the complete assembled unit from their website.

author: Martin72
author_rank: Super Contributor
timestamp: October 18, 2023, 09:34:32 pm
content: I changed the title to also write something about the construction of the LDO itself....Since janascard also offers the LDO completely, I have written to him and asked which supply is used there, or what kind of supply is recommended.In the meantime, I have designed a front panel that I will have made - And notice it looks pretty much like the finished version of the LDO....At Reichelt I have now ordered good BNC mounting sockets, a precision potentiometer and matching knob.The notch filter board is almost ready, only the OPA209 is still missing, because I ordered it in the wrong package...Pictures of the boards will follow.(The software is called "Frontplatten Designer" , you can design your frontplate and order it online)

author: Martin72
author_rank: Super Contributor
timestamp: October 20, 2023, 10:09:57 pm
content: QuoteHe wrote me back and send a schematic of the supply he use, it needs 12V AC and generates +/- 15Vdc.I generated a board from it, which I will order from JLCPCB soon.Then still order the front panel and set the notch filter when the OPA209 has arrived here.And then...Let's see.

author: Martin72
author_rank: Super Contributor
timestamp: October 28, 2023, 06:58:25 pm
content: QuoteArrived today, boy this is fast...The circuit boards positioned in the housing, but, that fits.Marking holes, drilling, etc., will be done on this long weekend.The front panel is in the supply, only the OPA209 for the notch filter is still missing, for a single component I order nothing from Mouser.

author: Martin72
author_rank: Super Contributor
timestamp: November 03, 2023, 07:04:06 pm
content: The front panel has arrived, it looks really good in terms of quality.And the characters are not printed, but engraved...

author: bozidarms
author_rank: Regular Contributor
timestamp: November 03, 2023, 08:23:07 pm
content: [ Specified attachment is not available ]QuoteI use both - Victor LDO, also Victor`s notch and Jan`s SilentSwitcher, can only recommend

author: bozidarms
author_rank: Regular Contributor
timestamp: November 04, 2023, 05:49:46 am
content: THD is about -135dB, rather limited with analyzer (RTX6001) capability.Measurement with notch (passive twin t notch deep is -80dB) clearly show that harmonics almost doesn't exist.Victor`s LDO is OPA 1656 based.Jan`s SilentSwitcher will do the job for your LDO.

author: Martin72
author_rank: Super Contributor
timestamp: November 04, 2023, 09:33:04 am
content: QuoteAh, now I get what you mean...https://diyaudiostore.com/products/linear-audio-silent-switcherNice....QuoteThe same goes for these.

author: kripton2035
author_rank: Super Contributor
timestamp: November 04, 2023, 09:46:55 am
content: Quotestrange thing they are out of stock for months, no plan to make new batches, and still they don't publish the schematics ...

author: bozidarms
author_rank: Regular Contributor
timestamp: November 04, 2023, 10:04:22 am
content: I would contact Jan directly, maybe is still some under the table...