Custom u cores anyone?
Started by unknown · · 62 posts · last reply 6 May 2012
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#26 ·
Yea the core material in the images look like Ferrite to me also and based on the inductance measurements it leads me to think that it has a permeability around 1000. In Stan's U.S. Patent #5,149,407 (page 19 section 6, line 6) says you can use M27 iron cores for the 5 coil VIC transformer. -
#27 ·
Thank you for the clarification. This is what I thought as well.
The closer we can build the unit to Stan's specs, the better the results will be. -
#28 ·
Tony, thanks for the info.
if the core was around 1000 perm wouldn't it be out of the Vic cards working frequency range? -
#29 ·
The permeability of the cores I'm using is 2000 and the inductance measurements with the same amount of wire as Stan's coils give me at least twice the inductance. Don's showed inductance measurements of 1263mH @ around 75 ohms for L1, with the 2000 perm. cores I'm getting measurements around 2500mH @ around 75 ohms for L1. So as you can see my perm. is too high and thats why Im thinking it should be around 1000. With powder Iron cores Im get an inductance of 350mH, which is too low. -
#30 ·
Cool thanks, then I guess that's the new number to shoot for and see what happens -
#31 ·
Anyone knows were cores with such permeability can be bought. Or if it is possible to fabricate such cores using resin and iron powder?
The nearest I can find are balun rods but have permeability of 400 not 1000
HM -
#32 · date not recorded
The powder iron cores that I tested where specially made by MicroMetal, but like I said it only gave me an inductance of around 350mH
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#33 · date not recorded
Tony, What was the thickness? -
#34 · date not recorded
they are 0.125" thick, 3" x 3" square slabs....here's the part #I349-40/.125 -
#35 · date not recorded
All,
I've made fine iron powder and epoxy cores and they will not saturate but have a inductance too low for us I think. It is much below 400uh and works nicely for 60hz but not much good at khz frequencies. Same experience with steel strips from an old microwave oven transformer. Since that experiment, I've bundled and put seven 1/4" ferrite rods through standard wire bobbins off the shelf and matched the ends with rectangular ferrite strips about five high. It works well and is cheap from ebay.
kb -
#36 ·
All,
I've made fine iron powder and epoxy cores and they will not saturate but have a inductance too low for us I think. It is much below 400uh and works nicely for 60hz but not much good at khz frequencies. Same experience with steel strips from an old microwave oven transformer. Since that experiment, I've bundled and put seven 1/4" ferrite rods through standard wire bobbins off the shelf and matched the ends with rectangular ferrite strips about five high. It works well and is cheap from ebay.
kb
What ferrite rods are you using?
Are they balun ferrite rods? -
#37 · date not recorded
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#38 · date not recorded
Those rods are 400perm. I think I have something pretty close to those but have not had any luck using them. What frequency range are you working with? -
#39 · date not recorded
It seems to work well across a wide frequency range. I L meter measure at 1.2h with seven of them bundled as a core using a standard spool of 1000' 28 gauge. My VIC has two sets of two for chokes on the five coil setup.
Question for Tony, Do you get the waveform by using a second diode across the negative secondary pointing to and connecting after the meyer diode?
kb -
#40 ·
Hi kickbackemf
Can you post a picture of your VIC ?
I have lots of these rods around but inductance readings look too low. I wound aprox 100 turn on one of them and resulted in only 0.6mH.
HM -
#41 · date not recorded
HM:
I've been playing around with 8 330uf capacitors in parallel at the variac rectifier to reduce the 60hz drop out in the waveform....
kbattachment_10492 attachment_10494 waveform.jpg kbvic.jpg
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#42 · date not recorded
HM:
ooopppsss, that was my MO transformer strip vic, no go
this is the ferrite rod and strip vic, primary is single layer iron wire over six single insulated layers of 1000' 28 gauge, the waveform comes from this oneattachment_10496 kbvicf.jpg
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#43 ·
Anyone know any good sources for 29 AWG magneti wire, or M27 electrical Steel sheet? -
#44 ·
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#45 · date not recorded
Hello,
Is anyone looking for u-cores. I have a place where I can get some. The material is Epcos N95 and the permeability is 3000.
The coats for a set is going to be $110 without shipping. This is what they went for them.
Josh -
#46 ·
Here is some info from National Magnetics Group regarding ferrite plates which could be fabricated by perhaps a water jet or laser. Unfortunately the minimum order is for 25 @ $30.00 each. You would need one plate per u-core half to duplicate Meyers core. Anyone got a better deal?
We do not make a M27 material so I am assuming you’re looking for a MnZn power ferrite. Is this product our M20 would be the available material, with 2000 initial perm. I have attached our data sheet. Our part number made with M20 would be; B-1377-M20. You have not provided a quantity so I have quoted our minimum order.
P/N: B-1377-M20
25 pcs $30.00 ea MOQ
Lead-time: 8-10 weeks
Let me know if you need different price breaks or have any questions.
Thank you,
Mark Northrup
National Magnetics Group
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#47 · date not recorded
I'll take one, now 29 other's here need to order.....
kb -
#48 · date not recorded
So the deal is we need two sheets and have to cut them our selves? -
#49 ·
Yes, the ferrite plates are 3.87" x 3.87" x .118". One plate should be sufficient to make one u-core (2 required for the VIC coil). I have not investigated the possibility of cutting with a water jet or laser yet but I don't see any reason why either could not be used to turn the plates into u-cores. The 8-10 week lead time slows the process down. If anyone knows of someone who actually stocks something similar on a shelf ready to sell that would be a plus. -
#50 ·
I'll take two plates as well, now we just need 13 more people