SY said:
Just goes to show there are two (minimum) ways to interpret anything observable.. My take is, any interaction either robs from the signal or adds to it in a delayed fashion.
Mike.
Parallel fusing was an interesting experiment.
Very Positive Results.
For all the right reasons.
Very Positive Results.
For all the right reasons.
For another spin on the retention of charge by dielectrics, there is as device called an electret thant can be mage of many dielectric materials (beeswax is one). To form an electret , you can heat up an appropriate material in a static electric field and let it cool with the field still applied. A Google search would probably find loads of stuff. There was an "Amateur Scentist" project on electrets back in the glory days of Scientific American (the magazine), which is how I know about the beeswax.
SY said:
Stuart, would this non-continuous metal structure still shield against EMI etc then?
Jan Didden
john curl said:
John, I don't think there is anything to counter, apart from the obvious personal issue that you try to depict me as attacking persons rather than ideas. I think most readers here will look through that posturing easily without needing my help. I'm not given to attacking persons.
No, it's the conflicting advice I see. And indeed you can use any amount of Delrin and Teflon internally for whatever reasons, that was not the issue. The issue was the enclosure: your milled aluminum vs Demian's Delrin. I think Demian's reply made it more clear and I read it such that in the final analysis there is still a need for a metal enclosure. Stuarts suggestion is interesting, but I don't have enough knowledge to judge whether isolated metal particles in a Delrin or similar material would still provide shielding. Maybe others do?
Jan Didden
Re: Transformer Core
This looks similar to aem unicore.
http://www.aemcores.com.au/IntroductiontoUnicore.htm
These are good cores and the transformers can be made with
very good regulation and efficiency.
The design allows high core efficiency similar to toroids, ie; grain
oriented steel, almost gapless, but as you mentioned more choices
for better coil geometry.
One thing to be careful of is mechanical noise, from memory it was
an issue. I think in the end, vacuum impregnated varnish was
required to keep them quiet.
T
chascode said:
This looks similar to aem unicore.
http://www.aemcores.com.au/IntroductiontoUnicore.htm
These are good cores and the transformers can be made with
very good regulation and efficiency.
The design allows high core efficiency similar to toroids, ie; grain
oriented steel, almost gapless, but as you mentioned more choices
for better coil geometry.
One thing to be careful of is mechanical noise, from memory it was
an issue. I think in the end, vacuum impregnated varnish was
required to keep them quiet.
T
Regarding materials and their ESD properties, teflon, as I remember it, was a very hot material. Creating and holding an ESD charge 
Might this be the reason a cable is holding a charge? John, why is your connector panel bulkhead made of teflon?
Might this be the reason a cable is holding a charge? John, why is your connector panel bulkhead made of teflon?flg said:Regarding materials and their ESD properties, teflon, as I remember it, was a very hot material. Creating and holding an ESD charge
I also choose to use Teflon (or PTFE) in similar locations for its very low DA factor and damping properties.
Regards,
janneman said:
I believe that it would, at least at higher frequencies. There's a capacitance between all of the particles. I'm familiar with some composite structures made this way that are used for RF absorption.
Re: Re: Transformer Core
It does indeed look like the AEM unicore, Terry.
Vacuum impregnation is very important. It reduces the audible vibration, which is a form of core loss, since the energy used to produce the vibration (at twice line frequency) is not producing useful mmf in the secondary windings. The epoxy compound we use has better thermal conductivity than air, so it fills air voids and thus helps reduce core and winding temperature.
The impregnation works well with 3% silicon iron cores, but with nickel or cobalt alloy cores it could cause magnetostriction that adversely affects the high permeability you paid so much money to get. Ni and Co toroid cores used to be available with a silicone-filled aluminum core box, but these days only nylon core boxes are available. The aluminum core box was nice, it concentrated the eddy currents around the core, producing a more uniform flux, and didn't transfer the force of the tightly-wound copper wire to the core.
I have some core samples of a new higher-temperature amorphous metglas alloy on order to check it's properties at high temperatures. If there is something interesting in the results I'll post it.
Terry Demol said:
It does indeed look like the AEM unicore, Terry.
Vacuum impregnation is very important. It reduces the audible vibration, which is a form of core loss, since the energy used to produce the vibration (at twice line frequency) is not producing useful mmf in the secondary windings. The epoxy compound we use has better thermal conductivity than air, so it fills air voids and thus helps reduce core and winding temperature.
The impregnation works well with 3% silicon iron cores, but with nickel or cobalt alloy cores it could cause magnetostriction that adversely affects the high permeability you paid so much money to get. Ni and Co toroid cores used to be available with a silicone-filled aluminum core box, but these days only nylon core boxes are available. The aluminum core box was nice, it concentrated the eddy currents around the core, producing a more uniform flux, and didn't transfer the force of the tightly-wound copper wire to the core.
I have some core samples of a new higher-temperature amorphous metglas alloy on order to check it's properties at high temperatures. If there is something interesting in the results I'll post it.
SY said:
Google for :
Akzo Nobel Ketjenblack carbon pellets, DuPont Zytel, RFI/EMI shielding of carbon fiber filled conductive resins (Q. Krüger MSc. Thesis)
SY said:
We use silver/nickel filled polysulfide gaskets for EMI control, along with labyrinth folded edges where two surfaces meet. The idea is to prevent any gaps greater than 1/10 wavelength to avoid inadvertent slot antennas.
There are two aspects to EMI: emissions and susceptibility. For simple control boxes with linear power supplies (similar to Blowtorch) susceptibility to outside magnetic and electric fields is the main issue. For our power conversion products, we can generate much higher EMI than the levels used for susceptibility testing. It all has to be moderated in the control of the MOSFET switching rise-time, or absorbed somehow in filters and shielding.
We have to be at least 10dB lower than the Mil-Spec susceptibility limits to avoid interfering with other equipment on the aircraft. This is called electromagnetic compatibility (EMC).
Yes, and the structure of the particles is dead critical for those types of composites to work properly. The kind of blacks that Jacco mentioned have a high structure factor, so you'll get more unwanted (for this application) DC and low frequency conductivity when loading it up for HF shielding. Flakes and spheres of metals or semiconductors have progressively lower structure and can be loaded in at progressively higher concentrations. There's also chopped fibers, and if the part is fabricated properly, one can even get significant anisotropic properties.
1audio said:
You need relative motion i.e. as in a microphone. Another thought experiment, if you could take an electret microphone and displace an electristatic voltmeter you would have created charge.
The free energy people make generators that suck energy forever out of super magnets or so they say. The magnetic equivalent.
When it comes to the composites, I just wander into the lab, dig through 3 filing cabinets of particle info..and then make something up..or order 'samples' (ahem) on the company letterhead- for the newer toys/particles/etc. One can do some funky things..... 🙂
For example, bats will fly right into (depends on the construction) a Goo Systems video screen. (Whack!) (Ouch-that's gotta hurt).
For example, bats will fly right into (depends on the construction) a Goo Systems video screen. (Whack!) (Ouch-that's gotta hurt).
Yes it is, as 'HARDENED OBSERVATION' often leads to: 'It can't be true, observation'.
This is often why, young, inexperienced inventors do better. It is hard to remain open-minded, after years of university, and industrial experience.
I have always had difficulty with this, and have paid the price of not attacking a problem until someone else really rubs my nose in it.
For example, this happened with output coils in power amps (used them for decades), high speed diodes (what is wrong with just using a 1N4007?) , switches (why not just use relays?) Teflon vs polystyrene caps. (But polystyrene is so much cheaper!) etc, etc.
I had to be led gently, but firmly to do what my 'experience' had shown me was either unnecessary, impractical, or reckless. All in the quest for better sound.
This is often why, young, inexperienced inventors do better. It is hard to remain open-minded, after years of university, and industrial experience.
I have always had difficulty with this, and have paid the price of not attacking a problem until someone else really rubs my nose in it.
For example, this happened with output coils in power amps (used them for decades), high speed diodes (what is wrong with just using a 1N4007?) , switches (why not just use relays?) Teflon vs polystyrene caps. (But polystyrene is so much cheaper!) etc, etc.
I had to be led gently, but firmly to do what my 'experience' had shown me was either unnecessary, impractical, or reckless. All in the quest for better sound.
Yes. Like:
Why would someone put 4 miniature fuseholders with a 1.25 amp fuse in each, on a power rail....over that of a single larger fuseholder with a single 5 amp fuse?
How ridiculous can you get?
Well....there are multitudes of reasons, when you think about it. To start..nonlinearities are defeated or curtailed in various ways and ratios. For one, current sharing is not an issue, if the contacts are solid. Think of the nature of a fuse.
It's also hard for the electrical approval guys to argue with it.
For you guys in the UK, try making a power tail (for a high powered audio amplifier) with four 5 amp fuses in parallel instead of a single 20A fuse. A cheap and quick way of seeing what I'm getting at. It won't be the perfect implementation of what I'm saying, but it will give a hint of what it can do. Perhaps an initial test might be best with a lighter load type device, like a source or preamp, but you should quickly get a handle on what it does. It's the cheapest way to get to the sonic effects of no fusing, without affecting fusing.
Why would someone put 4 miniature fuseholders with a 1.25 amp fuse in each, on a power rail....over that of a single larger fuseholder with a single 5 amp fuse?
How ridiculous can you get?
Well....there are multitudes of reasons, when you think about it. To start..nonlinearities are defeated or curtailed in various ways and ratios. For one, current sharing is not an issue, if the contacts are solid. Think of the nature of a fuse.
It's also hard for the electrical approval guys to argue with it.
For you guys in the UK, try making a power tail (for a high powered audio amplifier) with four 5 amp fuses in parallel instead of a single 20A fuse. A cheap and quick way of seeing what I'm getting at. It won't be the perfect implementation of what I'm saying, but it will give a hint of what it can do. Perhaps an initial test might be best with a lighter load type device, like a source or preamp, but you should quickly get a handle on what it does. It's the cheapest way to get to the sonic effects of no fusing, without affecting fusing.
KBK said:
I thought bats flew via ultrasound. I suppose that could the point, what I don't know. The connection to video?
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