stef1777 said:
How did you contact them? I wrote email to info@schuro.de.
And about those custom wound toroids you sent a link too. They might be nice, but I dont understand a word french
i'm sorry for this ot-post but i just couldn't let this one slip...
ewildgoose: the lady from audiokit (i think you mean sabina) is most definitely not useless. When my order got delivered at the wrong address she helped me very well in getting me my stuff back from the dutch postal service. She/Audiokit might be somewhat slow in answering (english) emails but they're cheap and they deliver fast.
if you don't like them, you could also try the french dealer who asks about twice as much for the same cabinets.
If you speak italian their responses are much faster, that's true.
about schuro: the response time to emails and orders seems to correlate with the value of the order/product information requested. Two people I know emailed them. The one requesting information about a very cheap thingy (no idea what) never got a reply, another guy i know did receive a reply (within the hour) about an order worth more than 200 euros.
go figure!
ewildgoose: the lady from audiokit (i think you mean sabina) is most definitely not useless. When my order got delivered at the wrong address she helped me very well in getting me my stuff back from the dutch postal service. She/Audiokit might be somewhat slow in answering (english) emails but they're cheap and they deliver fast.
if you don't like them, you could also try the french dealer who asks about twice as much for the same cabinets.
If you speak italian their responses are much faster, that's true.
about schuro: the response time to emails and orders seems to correlate with the value of the order/product information requested. Two people I know emailed them. The one requesting information about a very cheap thingy (no idea what) never got a reply, another guy i know did receive a reply (within the hour) about an order worth more than 200 euros.
go figure!
ALAIN:
ALAIN:
<<i've replaced my Elna main caps with big EPCOS Sikorel 105 15000/63 and it's an improvement (the best caps i've tried )>>
While everybody is happy with metal boxes I found your last post to be most interesting (I almost buy Elna Cerafines). I've search and I only found Sikorel caps for automotive applications. Are they these? Please tell us where to buy them (and also in the Americas) and what diffrences did you find between these and other caps.
Merci beaucoup...
Mauricio
ALAIN:
<<i've replaced my Elna main caps with big EPCOS Sikorel 105 15000/63 and it's an improvement (the best caps i've tried )>>
While everybody is happy with metal boxes I found your last post to be most interesting (I almost buy Elna Cerafines). I've search and I only found Sikorel caps for automotive applications. Are they these? Please tell us where to buy them (and also in the Americas) and what diffrences did you find between these and other caps.
Merci beaucoup...
Mauricio
Audiokit: i can wait, no problem.
Schuro: if small order, no answer. I placed 180€ yesterday and I've got the answer in 3 hours. I ordered BHC slit-foil caps.
You should order with a complete list of product, part number, quantities and prices. Indicate all personnal reference, and ask for the global total. He answer with the global total and how to pay.
Galaxy box in French: and they don't have them in stock !
Potted transformer: more expensive, bigger and low temp use
Schuro: if small order, no answer. I placed 180€ yesterday and I've got the answer in 3 hours. I ordered BHC slit-foil caps.
You should order with a complete list of product, part number, quantities and prices. Indicate all personnal reference, and ask for the global total. He answer with the global total and how to pay.
Galaxy box in French: and they don't have them in stock !
Potted transformer: more expensive, bigger and low temp use
The main incentive for potting a toroid is mechanical noise. The problem with square-section toroids is that the windings are tightened around the corners but are very loose on the flat sides. The effect is that some toroids produce an unacceptable amount of mechanical hum.ewildgoose said:
Round-section toroids do not have this problem.
Stray fields are normally absent from toroids on the condition that the windings are evenly distributed around the circumference of the core. Potting for magnetic reasons is not normally necessary.
Stray field from a transformer will show up as a minor increase in hum on the output signal. I find, however, that on some circuits it completely blows the sound, which becomes thin, shallow and confused.
Bruno Putzeys said:
I received my transformers today. The company I bought from make their own cores. Their cores have rounded corners as you described. I got a elecrostatic shield and a magnetic shield. Not sure if these will help. Also, I got a low flux design which means they are a lot larger, basically a 500VA transformer on a 625VA frame.
Just a silly question, I wanted to test the secondary voltages. Is there a procedure or risk powering the transformer with nothing connect on the secondaries other than multimeter?
First a question back. How on earth does one practically make an electrostatic shield (I presume you mean one between primary and secondary) on a toroid transformer?chrisb03 said:
There is no risk involved with running an unloaded transformer. If you are making measurements with a multimeter, it is good practice first to attach the multimeter, then to plug in - just a matter of not getting up to 70VAC (split secondary) across your person.
The question was, of course, how is it physically done. On an EI core one makes one (non-shorted!) turn of copper foil, but on a toriod that would be a hollow toroid with one side cut open. Not exactly practical.
I know sometimes a dummy winding is made and called a shield, but I don't see that as a shield in the true sense.
I know sometimes a dummy winding is made and called a shield, but I don't see that as a shield in the true sense.
Can anyone comment on the differences between the Tripath Evaluation boards and the UCD modules? I know that the Zaps and UCD's have been discussed but does Tripath offer any noticable differences for the dollar?
Are there substantial differences between the class D & T architecure?
Thanks,
goskers
Are there substantial differences between the class D & T architecure?
Thanks,
goskers
I've found this page surfing.
http://www.ciaudio.com/D100.html
The specs are close to the UcD180 module!!! May be inside?
http://www.ciaudio.com/D100.html
The specs are close to the UcD180 module!!! May be inside?
transformer shielding
My very simplified point of view about a transformer shield winding:
1st assumption:
All elements are lumped: Ccoupling, Lseries, Rseries (of the transformer windings)
2nd assumption:
considering common mode noise transmission from mains to secondary only
u1 is the primary noise voltage
u2 is the noise voltage across the shield inductivity
u3 is the secondary noise voltage
RL is the series resistance of the shield winding
C is the coupling capacity between the windings (C1 between primary and shield)
Ls is the inductance of the shield winding
XC = 1 / (omega * C)
XL = omega * L
u2 = u1 * (XLs + RLs) / [(RLs + XLs) + XC1]
The numerator will increase stronger with frequency than the denominator, because of the multiplication in contrast to the denominator summation.
It is not easy to make the C low, but one can keep the XLs near zero by putting a bifilar winding between pimary and secondary. Unfortunately this doubles the RLs, which keeps constant over frequency leastwise. This would end into:
u2 = u1 * 2*RLs / (2*RLs + XC1)
In this formula the frequency dependent raise of the noise coupling is determined by the XC1 only, not by XLs as before.
The main differences between the sheet shielding and the winding type are the inductances and the series resistances. The gaps between the twists(?) of the winding may act as slot antennas, if the noise frequency's Lambda steps into the range of the gap lengths. This would be valid for the sheet type too, if there is no (isolated) overlap.
They seem to make foil shieldings onto toroidal transformers: http://www.bsab.de/Produktinfo/body_produktinfo.html.
In my opinion the winding shield would help a bit, but not as well as expected.
To achieve better (electrostatic) shielding performance at higher frequencies, some facilities provide their transformers with a foil of high permeability (http://www.tauscher-transformatoren.de/html/techn_info_d.html). They may provide up to 20dB higher damping.
At last an example (http://www.rotima.ch/ro_ringkern/techn.htm):
Picture 5 shows measuring circuit and the typical characteristics of the asymmetrical Vnoise at transformers.
(1) Transformer without static shielding
(2) Transformer with one static shielding
(3) Transformer with two static shieldings.
Best regards, Timo
My very simplified point of view about a transformer shield winding:
1st assumption:
All elements are lumped: Ccoupling, Lseries, Rseries (of the transformer windings)
2nd assumption:
considering common mode noise transmission from mains to secondary only
u1 is the primary noise voltage
u2 is the noise voltage across the shield inductivity
u3 is the secondary noise voltage
RL is the series resistance of the shield winding
C is the coupling capacity between the windings (C1 between primary and shield)
Ls is the inductance of the shield winding
XC = 1 / (omega * C)
XL = omega * L
u2 = u1 * (XLs + RLs) / [(RLs + XLs) + XC1]
The numerator will increase stronger with frequency than the denominator, because of the multiplication in contrast to the denominator summation.
It is not easy to make the C low, but one can keep the XLs near zero by putting a bifilar winding between pimary and secondary. Unfortunately this doubles the RLs, which keeps constant over frequency leastwise. This would end into:
u2 = u1 * 2*RLs / (2*RLs + XC1)
In this formula the frequency dependent raise of the noise coupling is determined by the XC1 only, not by XLs as before.
The main differences between the sheet shielding and the winding type are the inductances and the series resistances. The gaps between the twists(?) of the winding may act as slot antennas, if the noise frequency's Lambda steps into the range of the gap lengths. This would be valid for the sheet type too, if there is no (isolated) overlap.
They seem to make foil shieldings onto toroidal transformers: http://www.bsab.de/Produktinfo/body_produktinfo.html.
In my opinion the winding shield would help a bit, but not as well as expected.
To achieve better (electrostatic) shielding performance at higher frequencies, some facilities provide their transformers with a foil of high permeability (http://www.tauscher-transformatoren.de/html/techn_info_d.html). They may provide up to 20dB higher damping.
At last an example (http://www.rotima.ch/ro_ringkern/techn.htm):
Picture 5 shows measuring circuit and the typical characteristics of the asymmetrical Vnoise at transformers.
(1) Transformer without static shielding
(2) Transformer with one static shielding
(3) Transformer with two static shieldings.
Best regards, Timo
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.