If you have any mismatch between the secondary coils with a common
ground, the core will tend to saturate when the amplifier is delivering DC
or low frequencies. The result is mechanical noise that critical customers
will complain about. Dual bridges and isolated secondaries avoid this issue.
😎
ground, the core will tend to saturate when the amplifier is delivering DC
or low frequencies. The result is mechanical noise that critical customers
will complain about. Dual bridges and isolated secondaries avoid this issue.
😎
When you use a center tap to ground, all the line noise that has passed thru the transformer by its C in now on the ground of the amplifier.
Has anyone thought of the C of the diodes? I have been trying out some high voltage (1KV) diodes with low C, with good results. I measured 18pf of C with these diodes. Less C for less noise passed thru when the doide is off.
If you look across all four diodes the c actually is going across the lines the same as the filter c.
Jcx look at the spectrum I showed decoupling the ct gives 10 db less noise. Measured no sim'd.
Nelson thanks for the answer. I also measure a small drop in the transformer's efficiency. Of course switching surges clean up most of that.
ES
measured is good but there are ways to skew results - unshielded toroid, deliberate miss connection of line hot
power amps usually have safety gnd connection
then system issues with safety gnd noise, gnd loops
where pri-sec C line noise coupling falls in the zoo of system and circuit level effects requires spelling out lots more assumptions
power amps usually have safety gnd connection
then system issues with safety gnd noise, gnd loops
where pri-sec C line noise coupling falls in the zoo of system and circuit level effects requires spelling out lots more assumptions
Adding two paralleled diodes upside down between the center transformer wire and ground ?
I like this approach because it also makes it much easier to keep charging currents out of the way of signal currents when you connect the power supplies to form the PSU ground after the filter capacitors.
I have a ground lifter between the secondary ground and the chassis (35A), with a resistor (22 Ohms IIRC) across the ground lifter.
I think snubbering the rectifier is also important to remove ringing as they come out of conduction.
There is no "Nobel Prize for economics".
Isn´t this called Neo-Liberalism what we have for 30 years now ?
Yes it´s the "Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel", a price invented by a bank not Alfred Nobel...
If you want to be a pedant, it's actually "Sveriges riksbanks pris i ekonomisk vetenskap till Alfred Nobels minne." But I'm sure you weren't. 😀
I don´t want to be a pedant ;-) but probably Alfred Nobels familiy is. From the Wikipedia article you linked in your post:
"Some critics argue that the prestige of the Prize in Economics derives in part from its association with the Nobel Prizes, an association that has often been a source of controversy. Among them is the Swedish human rights lawyer Peter Nobel, a great-grandson of Ludvig Nobel. Nobel criticizes the awarding institution of misusing his family's name, and states that no member of the Nobel family has ever had the intention of establishing a prize in economics."
"Some critics argue that the prestige of the Prize in Economics derives in part from its association with the Nobel Prizes, an association that has often been a source of controversy. Among them is the Swedish human rights lawyer Peter Nobel, a great-grandson of Ludvig Nobel. Nobel criticizes the awarding institution of misusing his family's name, and states that no member of the Nobel family has ever had the intention of establishing a prize in economics."
Well they do call you from Stockholm to tell you that you have won. (The call begins "This is the long distance operator calling from Stockholm..,") which is a bit different from the others sometimes. But you still get it at the same awards ceremony and are treated to all the same formalities.
Interestingly enough Herbert (78) and John (94) at one time lived about 3 blocks away from each other. Both would walk down the hill to what is now Carnegie Mellon.
Even as an undergrad John was a bit strange. The movie doesn't quite get his stomp right or his devotion to his always present attache case. It does illustrate his drinking.
Interestingly enough Herbert (78) and John (94) at one time lived about 3 blocks away from each other. Both would walk down the hill to what is now Carnegie Mellon.
Even as an undergrad John was a bit strange. The movie doesn't quite get his stomp right or his devotion to his always present attache case. It does illustrate his drinking.
I hope that Ed Simon or Rick Miller will give us further thoughts on power supply design. They both have worked on improvements to power supplies, and I trust that they have more to contribute.
Not to mention that the magnetic field radiated from the transformer will increase and will "look" much more nastier if the core approaches saturation.
So it might not only be a mechanical noise problem if any susceptible receiver loops are waiting.
You'll want to consider primary and secondary common and differential mode filtering, interwinding shielding, and snubbing (especially the secondaries). A broad-based approach to making quiet supplies is more effective than just focusing on one or two aspects and trying to rhodium plate them.
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