Toroidal Transformers in B'lore

[corbato]

George bhai,

Saar..you keep us salivating onleee
I can visualise the scenario. Your Welbourne and the 12 saal ka maal giving good company.

But if your latest acquisition features anything less than a decent pair of NOS 12AU7, them chuck them out (the tubes) immediately. I will send to you, free, a prefect pair of Telefunken NOS Ribbed Plates. This is one is on me. Kya karen. Compulsion hai naa. Gotta keep my source of 12 saal ka maal in good humour

 

[tcpip]

Re: Re: Re: Hum

For a majority of Power Amp I don't think that is a necessity. Just take care to orient it in such a way that the flux doesn’t interfere with the signal...

Okay, will try orientation without enclosure. What should I listen for to know there are any problems? Will it be just a clear hum, or do I look for more subtle problems? And if it doesn't work, I guess I'll turn it by 90 deg and try again.

BTW, I wrote to the www.toroidal.com chaps more than a week ago, asking them whether they could supply me four of their 15-0-15V, 500mA model. No answer.

Tarun

 

[tcpip]

ashwin, I used a toroid mostly for the size reduction. I am planning to try a cabinet design featured in Elektor, where they bolt on aluminium sheets to a pair of heatsinks. The heatsinks form the side walls, and the sheets form the top, bottom, rear and front panels. The largest heatsink extrusions I could find did not have enough height to fit an E-I of 225VA. Then there are other issues, like less EMI, simple means of mounting, etc.

I got heatsinks from Precious and Visha on L.Road (both source from the same place, I think, because they both carry the same catalog), and I've seen at least two sections with straight tall fins of 100mm width, and one of at least 180mm width. These can be purchased to any length you want, and they bill by the centimetre length. The widest one is priced at Rs.25/cm. Once you place an order, they cut a piece of the right length, clean the rough-cut edge somewhat using files, and then anodise it black. All this takes two weeks, but at least you can get good heatsinks of arbitrary lengths at a price a small fraction of the Weikfield ones in the US.

So, with these sizes, you can easily get a heatsink wide enough to stand on its side taller than even a fairly large E+I transformer. I once got a 600VA E+I made and its height is certainly less than 180mm. The 250VA one I got from Delhi is about 82mm tall.

Tarun

 

[ashwin]

I got heatsinks from Precious and Visha on L.Road (both source from the same place, I think, because they both carry the same catalog), and I've seen at least two sections with straight tall fins of 100mm width, and one of at least 180mm width. These can be purchased to any length you want, and they bill by the centimetre length. The widest one is priced at Rs.25/cm. Once you place an order, they cut a piece of the right length, clean the rough-cut edge somewhat using files, and then anodise it black. All this takes two weeks, but at least you can get good heatsinks of arbitrary lengths at a price a small fraction of the Weikfield ones in the US.

So, with these sizes, you can easily get a heatsink wide enough to stand on its side taller than even a fairly large E+I transformer. I once got a 600VA E+I made and its height is certainly less than 180mm. The 250VA one I got from Delhi is about 82mm tall.

Tarun

Argh! why isn't there such a place in Bangalore? Does someone know of such a place in B'lore?

- Ashwin

 

[gjo]

BTW, I wrote to the www.toroidal.com chaps more than a week ago, asking them whether they could supply me four of their 15-0-15V, 500mA model. No answer.

Tarun

FYI the email id for these guys is miracle@vsnl.com. Ph 23485149. If you need me to talk to them let me know. I found them to be very prompt. You can email me offlist at gjo@dtsam.com

Ashok ( alias Gen Al Sahaf)

Tubes are 12AU7 JJs, and not NOS. So I may take you up on your very generous offer. I have done the parts list inventory today, found two resistors short (10K, 2w, will buy them locally) hope to start on assembly shortly. Luckily I had bought some good silver solder from Welborne Labs last year for future projects.

George

P.S. I just got the Diana Krall Live in Paris CD and am enjoying listening to her.

 

[peterpan73]

About Torodal Transformers for Ham Radio

OK I .... I am a Ham radio operator (besides a novice Audio DIY) and am homebrewing a 35 Ampere 13.8V DC power supply for my transceivers. Now can someone tell me how much it would cost me to buy one of those nice toroid transformers with an appropriate VA rating for my application and from where in india??

peterpan73

 

[tcpip]

Re: Re: thanks

Those are line matching transformer and not OPT's. They are used mostly in running long lengths of connector to Horns (you know...chonga’s..) spread across several zones.

Have you checked out the audio frequency transformers on www.rsindia.com? I found quite a range. Unfortunately, I have absolutely no knowledge of such stuff, so I don't know whether it'll meet the needs of you bottlehead types.

Argh! why isn't there such a place in Bangalore? Does someone know of such a place in B'lore?

Hey, don't insult India's only cosmopolitan city by comparing it with small towns like B'lore and Sunnyvale and other Silicon Valley shanty towns.

BTW, you can get quite a large sample of high-power heatsinks from RS Components. Check out www.rsindia.com. I was just looking through their Website, and was quite impressed. Unlike the hand-made stuff on L.Road, these have fixed lengths, but I daresay one of them may meet your needs. They have extrusions of widths greater than 200mm... what more does one need?

Tarun

 

[tcpip]

FYI the email id for these guys is miracle@vsnl.com.

That's the email address I wrote to, and it didn't even bounce back.

If you need me to talk to them let me know....

If it's not too much trouble, will you please ask them whether they'll be willing to deliver four toroidal transformers, 15-0-15V, 500mA, to Bombay? I can't even tell you the model number; their Website is timing out each time I try. And I'm not in a hurry; I can even wait a month for your reply.

P.S. I just got the Diana Krall Live in Paris CD and am enjoying listening to her.

Great CD! The term that best describes her piano playing style on some of those tracks is probably "rock piano." My favourite from that album is probably track 9... "Oh I could drink a crate of you and still be on my feet..." She's really poured her heart out into that one.

Tarun

 

[gjo]

Hi Tarun

I just called Nilesh's office, he's expected back after an hour and half, will try later today if I can, otherwise tomorrow. I have a few jobs to do today, so I may overlook calling him if I dont remember.

I have four of the other Diana Krall CDs-all are good. Thank God for CD burners!! There are also a lot of American artistes who's labels are not available here easily, but who are also very good. In fact I got a couple of Diana Krall albums from the US about two years ago, after someone recommended her music. The late Eva Cassidy is another really good singer..Another good group is Phish. Even CDs of some golden oldies like BS&T arent easily available here.


George

 

[gjo]

Spoke to Nilesh

Tarun

I just spoke to Nilesh, and he said that he sees the email himself, doesnt recall your email. Anyway he wants you to resend your enquiry to him at the same email id, he will respond directly, as soon as he sees it.

In case you dont hear from him after a reasonable time frame let me know.

George

 

[tcpip]

Re: Spoke to Nilesh

I just spoke to Nilesh, and he said that he sees the email himself, doesnt recall your email. Anyway he wants you to resend your enquiry to him at the same email id, he will respond directly, as soon as he sees it.

You're a real brick. Thanks a ton.

Tarun

 

[tcpip]

I just called Nilesh's office, he's expected back after an hour and half, will try later today if I can, otherwise tomorrow. I have a few jobs to do today, so I may overlook calling him if I dont remember.

Just asked my friend to re-send his email to Miracle. Has been re-sent. Let me see whether I get replies this time.

I have four of the other Diana Krall CDs-all are good.

I have just two DK CDs in all. One is "The Look of Love" and the other is Paris live. I have been curious about Eva Cassidy; will pick up something whenever I get a chance next. I recently was gifted a Kiri Te Kanawa CD by my wife for my birthday. Her voice is really something, but this album (a collection of "standards" sung with different big bands at different times) is a bit more of orchestra than I'd have liked. I would like to see her sing with just her plain voice sometime. Maybe I'll find some such album someday.

Two other female singers I've recently discovered (they've both been around for years) are Bonnie Raitt and Patricia Barber. After "Cafe Blue", I'm now a total PB fan. I believe a new album has been released; I'll see if any of my overseas friends will buy it for me. I believe some of them are even coming out on SACD, which should be most interesting... as of now I have precisely four SACDs. And Bonnie Raitt too is really worth re-visiting. Do you like these singers?

Tarun

 

[tcpip]

Re: About Torodal Transformers for Ham Radio

...am homebrewing a 35 Ampere 13.8V DC power supply for my transceivers. Now can someone tell me how much it would cost me to buy one of those nice toroid transformers with an appropriate VA rating for my application and from where in india??

You seem to be talking of something like 500VA, roughly. I once got a hefty 600VA transformer made (E+I) for Rs.2750 in Bombay, from a winding works in L.Road. I don't know whether too many people make off-the-shelf 500VA transfies to the specs you want (your current requirement is "abnormally" high , while voltage rating is low), so you may have no option but to get a custom job done. If you are on a budget, and space is not much of a problem, why don't you go the E+I way?

Tarun

 

[peterpan73]

ABOUT MY HI-AMP TOROID REQ

Well I already have a custom wound E-I transformer with the same specs but I have a lot of problems using it for RF work, EMI, excessive back RF leakage owing to antenna system imp.mismatches and other ground loop probs besides hum, inspite of really good LC filtering. I am hoping to try toroids to lessen if not entirely eliminate my noise probs as most MNCs manufacturing PSUs for ham radio purpose use the same.

I don't see or know anyone making the same in North east India.

Please help!

Peterpan73

 

[peterpan73]

Audio isolation trannies and crossover schematics required

Hello all,

is there any Inc in India manufacturing these nice Audio isolation trannys that I am hoping to employ in my new homebrew audio amp project. It is a 100W X 10 board amp rack mounted for live/stage use. I intend to use isolated tranny input isolation stages with flat responses in the preamp input of each of these 100W amps to make balanced inputs for connecting to XLR sockets for the amps. I do not want opamp balanced inputs because I have no time making additional circuitry for that. besides modifyuing my present unbalanced input preamp stage circuitry into a balanced input one is not contemplated owing to the fact that the PCBs were bought in kit form to minimise PCB making/etching hassles and I want to finish off this project ASAP. Further more I do not intend using external DI boxes for my inputs. I find the sight of DI boxes dangling everywhere an eyesore.

ALSO Considering THIS TO BE a powerful 1KW RMS power amp consisting of 10 boards, I would appreciate it very much if any of our friends here could help me in recommending an appropriate VA rating for the power toroid tranny to accomodate 1kw of power at 18V max.

Please direct me to useful Indian resources or if they are not known to you, at least to the more promising ones. I would also like to know where I could procure Jensen isolation trannies in India.

I am also looking for 4th order two or three way active crossover schematics employing NE5532s.

Regards and peace to all in the forum.
peterpan73
(DIY audio novice)

 

[peterpan73]

About Rsindia

I checked into the www.rsindia site and tried to get a quick quote for my selected items. It tells me that my items cost P.O.A. What does that mean?

Peterpan73

 

[gjo]

Tarun

I have Patricia Barber Companion, got it a couple of years ago. I have a fairly large collection of American female vocal-Barbra Streisand, Linda Ronstadt, Carole King, Carly Simon. Joan Baez, Linda Eder(quite good), Faith Hill, Emmylou Harris,Sarah McLachlan, etc, etc. By and large I find that I enjoy listening to them. I plan to get some Alison Krauss when I go to the US hopefully sometime soon. I havent heard Bonnie Riatt, though I have heard of her.

I picked up Norah Jones CD recently it's quite good(hadnt heard the album before I bought it)..Like Navin I( and my sons) have maybe 550-600 CDs and the collection is growing rapidly. My sons are now into MP3, especially after I added a Kenwood CD/MP3 in my car , with Focal drivers, and bought a 120GIG HDD for my son so he could store MP3s to his hearts content..

For them .wav is passe!

I thnk we need to do a swap sometime, would have loved to come via Bombay on my next trip to the US, but with Lufthansa operating direct flights, it's worth paying the premium and avoid the hassles of Santacruz and Sahar-for us folks its really nightmarish walking the plank there-the touts, the weather and the stress of one extra layover are just too much for me to handle-esp on the way back..

Patrick

Let me know the exact specs-or even better email Nilesh Vad, if he doesnt reply in a reasonable time, send a reminder and let me know, I will follow up. Your specs are not complete-the toroidals will only output AC, which you will need to rectify to convert to DC. Check the website and see which model you want from them.

George

 

[peterpan73]

About my toroid regquirements

OK thanks there Tarun.

Don't worry about the rectification.. I'll do that... I'm more worried if I can ever get my hands on such a toroid. 30 to 35 amps at say 15 Volts AC secondary is all that I'm looking for in the V-0-V version.


Peterpan73

 

[peterpan73]

Correction

George not Tarun I mean

 

[peterpan73]

Two toroids needed not one.

Hello all

Thanks again Tarun and George. Yes these are two seperate toroids I need. One is for my Ham radio POwer supply Unit and the other one for my 1KW/10 Amp. Each amp board of the latter project outputs 100WRMS and consumes 5 Amps at 18VDC, and so i presume I will need a 50 Amp Toroid at 20 V or so AC. Probably 25 Amps each in two toroids to break the heat will also do so long that price differences are not too significant.


I am also in great need for small ferrite and iron core toroid cores of types FT-240-61, T-12 to 200 and FT 23 to 114 in different Mixes (u of 1 to 75 for Iron and 40 to 5000 for ferrites).

Rs india gives me a P.O.A. for a quote what does this mean??


Regards
peterpan73