PCB and Elko GB
Hi,
I'm going to order the mentioned Elkos these days. I'm sending an email to all the interested guys probably on weekend.
I seems that I don't have to start a second PCB order. Don't mind
The one who is interested in I can send one of my spares.
So what I want to say, is, please type in your name in the wiki if you are interested in this or that.
Has anyone of you an idea about a transformator just for the frontend psu? Even I have been looking quote a while, I just found nothing
I'd prefer a 40 A trafo with 4x 36 V. Don't want to use a toroid - would prefer an R-core trafo. Maybe somebody has got an idea? Would be highly appreciated
Cheers Ernst
Hi,
I'm going to order the mentioned Elkos these days. I'm sending an email to all the interested guys probably on weekend.
I seems that I don't have to start a second PCB order. Don't mind
The one who is interested in I can send one of my spares. So what I want to say, is, please type in your name in the wiki if you are interested in this or that.
Has anyone of you an idea about a transformator just for the frontend psu? Even I have been looking quote a while, I just found nothing
I'd prefer a 40 A trafo with 4x 36 V. Don't want to use a toroid - would prefer an R-core trafo. Maybe somebody has got an idea? Would be highly appreciated
Cheers Ernst
While waiting for word back from the R-core manufacturer (which has been frustrating due to communication with a middle man), I have checked on getting toroids made in North America. I have received a quote on a priliminary spec as follows:
50/60Hz, electrostatic shield,
OD: 5.3", HT: 2.4"
Primaries:
2 x 0-110-120v
Secondaries (bifilar wound):
Sec # 1 30V @ 4.35amps, 25V @ 5.2 amps.
Sec # 2 30V @ 4.35amps, 25V @ 5.2 amps.
Sec # 4 39V @ 0.21 amps, 34V @ 0.235 amps.
Sec # 4 39V @ 0.21 amps, 34V @ 0.235 amps.
Regulation on the 30V secondaries is 4.4%
Regulation on the 39V secondaries is 4.62%
Price $92 each, $85 for 10 or more.
If there are buyers only in the US or Canada, a single 120v primary could be used.
Price to ship to USA locations:
Postage on 1 pcs = US $ 21.00
Postage on 2 pcs = US $ 31.50
Postage on 4 pcs = US $ 50.00
They also can pot and metal enclose the transformers for extra cost.
Just trying to gauge the interest to see if there is interest in 10 or more before further negotiations.
50/60Hz, electrostatic shield,
OD: 5.3", HT: 2.4"
Primaries:
2 x 0-110-120v
Secondaries (bifilar wound):
Sec # 1 30V @ 4.35amps, 25V @ 5.2 amps.
Sec # 2 30V @ 4.35amps, 25V @ 5.2 amps.
Sec # 4 39V @ 0.21 amps, 34V @ 0.235 amps.
Sec # 4 39V @ 0.21 amps, 34V @ 0.235 amps.
Regulation on the 30V secondaries is 4.4%
Regulation on the 39V secondaries is 4.62%
Price $92 each, $85 for 10 or more.
If there are buyers only in the US or Canada, a single 120v primary could be used.
Price to ship to USA locations:
Postage on 1 pcs = US $ 21.00
Postage on 2 pcs = US $ 31.50
Postage on 4 pcs = US $ 50.00
They also can pot and metal enclose the transformers for extra cost.
Just trying to gauge the interest to see if there is interest in 10 or more before further negotiations.
toroid for front end
Hi,
when I was taking to Mihai, he did not recommend a toroid for front end due to capacitive coupling of mains mush. Not that important for the power buffer stage but very influencing to front end. So therefor he recommends a transformator, that's got separation of primary and secondary windings.
Cheers Ernst
Hi,
when I was taking to Mihai, he did not recommend a toroid for front end due to capacitive coupling of mains mush. Not that important for the power buffer stage but very influencing to front end. So therefor he recommends a transformator, that's got separation of primary and secondary windings.
Cheers Ernst
pooge said:
R-core manufacture is a little different than toroidal production.
R-core transformer producers do not use a range of secondary wire diameters, but roll on multiple windings in parallel instead.
A small VA size dual secondary R-core has a single winding per secondary, the bigger ones have 4 windings for each secondary.
Getting a 300VA and larger R-core with 4 secondaries made may not be technically feasable, or very expensive.
R-core
Jacco,
Thanks for your explanation. Didn't know.
Mihai has got two R-core transformers in his amp - this can be seen on a later photo in his own thread. A small one for the front end, probably 50VA and a big one for the power buffer in his amp. Small one with 4x36V / 50 VA is a bit tricky to get. No one in Europe offers. Big one you can get easily from france. Is not too expansive. I would do, if I haven't two perfect fitting toroids in spare. So I'm going to use toroids for the rear end and an R-core for the front end psu. I think this is the second best technical, but best economical solution. Still pretty good for a second best....
Cheers Ernst
Jacco,
Thanks for your explanation. Didn't know.
Mihai has got two R-core transformers in his amp - this can be seen on a later photo in his own thread. A small one for the front end, probably 50VA and a big one for the power buffer in his amp. Small one with 4x36V / 50 VA is a bit tricky to get. No one in Europe offers. Big one you can get easily from france. Is not too expansive. I would do, if I haven't two perfect fitting toroids in spare. So I'm going to use toroids for the rear end and an R-core for the front end psu. I think this is the second best technical, but best economical solution. Still pretty good for a second best....
Cheers Ernst
Re: R-core
Are you sure?
This is my workaround:
http://www.selectronic.fr/article.asp?article_ref_entier=90.2051-9999
Unwind the secondaries and wind with a smaller diameter wire 4 x 35...38V
The power stage is supplied with this:
http://www.selectronic.fr/article.asp?article_ref_entier=90.3256-9999
one per channel
ernesternest said:
Are you sure?
This is my workaround:
http://www.selectronic.fr/article.asp?article_ref_entier=90.2051-9999
Unwind the secondaries and wind with a smaller diameter wire 4 x 35...38V
The power stage is supplied with this:
http://www.selectronic.fr/article.asp?article_ref_entier=90.3256-9999
one per channel
Mihai,
nobody did, but maybe of interest to Pooge as he's negotiating with an R-core manufacturer.
Stereo amp assembling is throwing away one of the major advantages a DIY-er has, imo.
With a DIY winding wheel rig, it is real easy to rewind an R-core.
Downside of R-cores is that the secondaries are wound on top of eachother.(the multiple parallel secondary versions)
nobody did, but maybe of interest to Pooge as he's negotiating with an R-core manufacturer.
Stereo amp assembling is throwing away one of the major advantages a DIY-er has, imo.
roender said:
With a DIY winding wheel rig, it is real easy to rewind an R-core.
Downside of R-cores is that the secondaries are wound on top of eachother.(the multiple parallel secondary versions)
modified R-core
Hi Mihai,
ok, self customized - not bad.
I of course was talking about ready made ones. Found only some far east (custom made) with help of a very nice guy that took part in the pcb GB. Haven't bought so far. Modify the french one is pretty good idea
How much work? Did you separate core therefor? Think yuo have to. Would you mind telling wire diameter and number of windings?
Cheers Ernst
Hi Mihai,
ok, self customized - not bad.
I of course was talking about ready made ones. Found only some far east (custom made) with help of a very nice guy that took part in the pcb GB. Haven't bought so far. Modify the french one is pretty good idea
How much work? Did you separate core therefor? Think yuo have to. Would you mind telling wire diameter and number of windings?
Cheers Ernst
The stock French R-cores only provide primary voltage for European mains voltages. No help for us North American builders. Not interested in tearing apart a transformer to rewind it.
I spec'd electrostatic shield and bifilar windings on toroids to help with high frequency bleeding. I believe that adequate filtering can also help. That's where bifilar windings come in. Not sure why R-core would be that much better for a regulated stage, anyway. Also, I believe that how the grounding is handled may make a bigger difference. I see no reason to have ground currents go back to the transformer, but with two secondaries, one could connect them together for a "center tap". I'll use a bridge for each secondary, and not connect them together until the board.
I would still like to obtain an R-core, but shipping them from the other side of the earth vs. fairly locally may become a huge factor. Also, the toroid company does not require a set-up fee, and I have no problem communicating. Getting separate transformers would be even more expensive. Also, the R-core manufacturer recommends buying a single one for $200 to test before ordering the rest. That extra cost would have to be spread to others. I'm fairly confident that the toroids would not have to go with this process, since I'm not speaking through a middle man.
I spec'd electrostatic shield and bifilar windings on toroids to help with high frequency bleeding. I believe that adequate filtering can also help. That's where bifilar windings come in. Not sure why R-core would be that much better for a regulated stage, anyway. Also, I believe that how the grounding is handled may make a bigger difference. I see no reason to have ground currents go back to the transformer, but with two secondaries, one could connect them together for a "center tap". I'll use a bridge for each secondary, and not connect them together until the board.
I would still like to obtain an R-core, but shipping them from the other side of the earth vs. fairly locally may become a huge factor. Also, the toroid company does not require a set-up fee, and I have no problem communicating. Getting separate transformers would be even more expensive. Also, the R-core manufacturer recommends buying a single one for $200 to test before ordering the rest. That extra cost would have to be spread to others. I'm fairly confident that the toroids would not have to go with this process, since I'm not speaking through a middle man.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.