Sjöström Audio DIY forum

Projects => Headphone amplifiers => Topic started by: cota on March 21, 2009, 03:17:14 AM

Title: QRV-08 (General Questions)
Post by: cota on March 21, 2009, 03:17:14 AM
This seems like a good topic to have, such that a repository of QRV-08 questions / answers gets established.
I can tell that I am going to have a few questions here and there. But first I am just going through the parts list and making sure I can get equivalent parts to what you listed.

Anyways I was wondering what you would recommend for the pair of transformers to be used on 120V/60Hz? I was looking at Amveco's 70023 (http://www.amveco.com/Low_Profile_PC.htm), however it is slightly bigger then the one you used. I suppose I could mount them off the board, but that would be less then ideal. Not really sure how much space I would have on the board?
As for the capacitors, I am assuming I can pretty much use any that are similar, i.e. I am assuming that you didn't get super specific about the characteristics of each capacitor? As I am going to end up getting ones from different manufactures then you have listed. It would of course be ideal if I could order all the components through mouser, but I might have to hit up digi-key (for the transformer). 

Oh I also wanted to make sure that you are still planning to sell the PCB boards as I probably won't be building it until summer time (40 or so days), yet I figure in the meantime I will start to gather up all the parts.

Ryan
Title: Re: QRV-08 (General Questions)
Post by: peranders on March 21, 2009, 07:42:55 AM
You can use 230/24 Hahn transformers, even for 60 Hz. People have done that.

Yes I have boards.... no, worries.

Most caps are for decoupling so the material X7R would be fine except for the input cap (PPS or some other good type) and the compensation cap, NP0.
Title: Re: QRV-08 (General Questions)
Post by: qusp on February 14, 2010, 01:51:27 PM
hi, looking for a transformer for QVR08 that I can get at digikey; they dont seem to have the hahn either. also a little off topic, but the same question for the JSR06. there are so many on digikey and since these are PCB mounted with very specific hole mountings it makes it a laborious task to find a substitute. hopefull you have an idea of one already. thanks
Title: Re: QRV-08 (General Questions)
Post by: peranders on February 14, 2010, 02:14:51 PM
I have 2 x 18 VAC for the JSR06 if you are interested. I can also get the small transformers for the QRV08.
Title: Re: QRV-08 (General Questions)
Post by: qusp on February 14, 2010, 03:32:48 PM
damn, I knew I should have asked you before you shipped the PCBs. ok i'll take the ones for the qrv08 (x4) and do you have access to any with 2 x 20v secondaries? because I would like to be using the JSR06 as a power supply/pre-reg for a range of your other regs varying from (up to)18vdc (minimum 15vdc) down to 5vdc. will the dual 18va give me enough output to cover the drop over the SSR01/02/JSR01 @ 15vdc output?
Title: Re: QRV-08 (General Questions)
Post by: peranders on February 14, 2010, 03:45:31 PM
18 VAC is enough of you want 15 VDC out. If you use the preregulator you must have 4-5 V more than the output voltage. If you run without a pregregulator 3 V more is enough.
Title: Re: QRV-08 (General Questions)
Post by: qusp on February 14, 2010, 05:32:53 PM
hmm, I want to go from transformer->JSR06 @XX VDC->SSR01/02/JSR01 @ 15vdc max down to 5VDC minimum using the multiple outputs of the JSR06 to drive 4 separate regulators for both digital supplies and output stage of a dac (different dac to the one we have been talking about)

so by the sounds of it this 18VAC will not be enough. perhaps this is a better job for RFB03->reservoir->4 x regs->DAC?? or are there transformers of a suitable size that will put out 2 x 22vac?
Title: Re: QRV-08 (General Questions)
Post by: qusp on February 14, 2010, 05:52:34 PM
this is getting off topic. I will start a new thread tomorrow. but I will get the transformers for the QRV08 for sure. need to think on the power distribution for this other project, but if you could perhaps tell me in the other thread i'm posting in if there is a more powerful transformer that will fit the JSR06?
Title: Re: QRV-08 (General Questions)
Post by: peranders on February 15, 2010, 09:51:44 AM
As I have told you before: It might be an idea to first state what you actually need and then investigate what you might use.

Desired output voltages
Estimated max output currents

When you know this you can design towards the mains voltage.
Title: Re: QRV-08 (General Questions)
Post by: qusp on February 16, 2010, 11:56:59 AM
nevermind, posted in the other thread