| Author |
Message |
Michael
Guest
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 Posted:
Mon Mar 21, 2005 11:14 pm Post subject:
Re: Toroid Core for LED V Boost |
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John Popelish wrote:
| Quote: |
Michael wrote:
This discussion has picqued my interest. I gotta fidn some more "donuts" and
have at it.
Excellent! If you have trouble finding similar pairs, let me know and
I will mail you a few.
--
John Popelish
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Tnx, John.
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Michael
Guest
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| Posted:
Mon Mar 21, 2005 11:28 pm Post subject:
Re: Toroid Core for LED V Boost |
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"Watson A.Name - \"Watt Sun, the Dark Remover\"" wrote:
| Quote: |
"Michael" <NoSpam@att.net> wrote in message
news:423E5041.AFDA3AC@att.net...
"Watson A.Name - \"Watt Sun, the Dark Remover\"" wrote:
"Michael" <NoSpam@att.net> wrote in message
news:423DB20B.29D18D55@att.net...
"Watson A.Name - \"Watt Sun, the Dark Remover\"" wrote:
The toroid cores that I've been using for the V boost circuits
I've
built are similar to this one. I think mine may be a slight bit
larger.
They are commonly used on mouse and keyboard cables as RFI
suppressors.
http://www.mpja.com/productview.asp?product=12406+FL
The ones I use were pulled from a couple PC power supplies. Two
of
theses are
identical, 5/8" O.D. x 1/8" high with 3/8" I.D, are shaped like
miniature bagels
(i.e. have no sharp corners), and have a rough surface. Have to
be
careful not
to abrade the wire enamel while winding.
One (as yet used) is smaller, 3/8" I.D. x 1/8" high with 3/16"
I.D.,
with smooth
surface and sharp corners.
One very nice toroid, about the same dimensions as above, is
completely coated
with a smooth white material, some kind of plastic or epoxy. I
used
it in the
first booster I ever built (several days ago). It can use more
turns,
so I'll
strip it and rewind sometime.
Enameled wire - about 20AWG - was stripped off small transformers
from
the same
PC power supplies.
My latest booster design uses one of the rough-surface toroids
(above)
and the
20# wire. I put a new AA in it at 3:30 PM on Friday afternoon and
it's still
running as I write this (12:21 PM), nearly 45 hours. The All
Electronics bright
white LED is dim now compared to its dazzling self when the
battery
was fresh,
but the light is sufficient that it could be used for close-in
(12" or
so)
work. Transistor is a "wimpy 2N3904". 1K base resistor.
You didn't say what the total current was from a fresh AA cell. I
put a
transistor socket on one of my circuits. I found that with the
2N3904 I
get about 20 to 40mA total, sometimes it goes up a bit because the
transistor is getting warmer (not so good, expecially if it's a hot
day). With the 2N4402, roughly double that, 50 to 80mA, and it
doesn't
get warm. With the BC337 or BC338 I get 70 to 100mA total current,
sometimes a bit more. With the ZTX650, 2SD965, NTE11, etc., total
current will go up dramatically, sometimes 200mA, so it really needs
to
have two or more LEDs. If you check the datasheets, say, from
Fairchild, the 2N4401 has roughly twice the chip area as the 2N3904.
DVM read 45ma. Couldn't measure any of the real nitty-gritty because
my o'scope
is ... er ... resting.
Yeah, I agree that the 2N3904 is contarindicated for this app. but
there's
nothing better in theparts bins. Ya gotta understand that most of my
semiconductor stash dates from my A.F. days (late 60's) and tecnician
days
(early 70's).
Get some transistors on Ebay, for a few dollars including shipping.
I checked out a couple photo shops, hoping to get my hands on some
disposable
camera flash guts as you(?) suggested, and was told at both places
that they
don't toss disposables. They turn 'em in for cash. Ah well ......
some Zetex
goodies will be coming soon.
Zetex transistors are overpricesd if you buy them from a distrib. The
turkeys turn the disposables back in and they refill them and resell
them as new. Dirty, steenkin' rats.
|
Hard on you and me but easy on the environment. I wouldn't complain very loudly
about "refilling" because I'm a dyed-in-the-wool dumpster diver.
| Quote: | Try Rite Aid, Sav-on, Albertson's or other such drugstores, amaybe even
Walgreen's. I opened one up recently and found a 2SD2470, which looks
suspiciously like a ZTX650 - same tiny case.
|
Tnx for the heads-up. I think we do have a Rite Aid around here (across from
Rat Shack, coincidently). Forgot all about that drug store. It's a mile from
where I live, while CVS is just around the corner from me.
---
Michael |
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John Popelish
Guest
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| Posted:
Mon Mar 21, 2005 11:34 pm Post subject:
Re: Toroid Core for LED V Boost |
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Michael wrote:
| Quote: |
John Popelish wrote:
Excellent! If you have trouble finding similar pairs, let me know and
I will mail you a few.
Tnx, John.
|
No problem. It is my hobby to collect cores, so I have a pile of
them. Just email me with your address.
Another way to do this experiment is to get one of those split beads
that have a plastic shell that snaps it around a cable. You can place
various paper shims between the core halves and produce various gapped
configurations. The only problem is that these cores are so big that
you have to scale the whole circuit way up ot get meaningful results,
and there is no way to get the reference ungapped configuration,
because the core cut surfaces are not polished, so even a no paper
example has some effective gap.
--
John Popelish
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Michael
Guest
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| Posted:
Mon Mar 21, 2005 11:43 pm Post subject:
Update on my V boost |
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Just passed the 69-hour point and that sucker is still going, though markedly
dimmer than yesterday at this time. I can read 6-point Courier (with some
difficulty) with page about 1 foot away from LED. |
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Fred Art
Guest
|
| Posted:
Tue Mar 22, 2005 4:28 am Post subject:
Re: Toroid Core for LED V Boost |
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Michael <NoSpam@att.net> while reading the NewsGroups, express out
opinion in news:423E5041.AFDA3AC@att.net:
| Quote: | I checked out a couple photo shops, hoping to get my hands on
some disposable camera flash guts as you(?) suggested, and was
told at both places that they don't toss disposables. They turn
'em in for cash. Ah well ...... some Zetex goodies will be
coming soon.
|
Check out Ebay stuff like this is available.
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&rd=1&item=7501877040
&ssPageName=STRK:MESE:IT
F.Art |
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Joerg
Guest
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| Posted:
Tue Mar 22, 2005 6:10 am Post subject:
Re: Toroid Core for LED V Boost |
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Hello John,
| Quote: | Voltage boost regulators store energy in the magnetic field of the
inductor first, and dump it to the load second. Ungapped ferrite
cores are not so efficient in this mode, since the core absorbs a
significant fraction of the energy stored, each cycle. ...
|
This depends on the material. The switchers I designed with non-gapped
toroids ran efficiently. The normal losses were all accounted for, such
as those in the transistor, the diode, the ESR etc. but pretty much none
in the inductor. No ringing, nice linear ramps and the cores didn't get
hot. Mostly Fair-Rite stuff.
| Quote: | ...Cores with a small air gap store most of their magnetic energy in the
gap, which absorbs no energy. ...
|
Yes, but the whole inductor becomes a lot larger because of the
substantial drop in AL value.
Regards, Joerg
http://www.analogconsultants.com |
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John Popelish
Guest
|
| Posted:
Tue Mar 22, 2005 6:10 am Post subject:
Re: Toroid Core for LED V Boost |
|
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Joerg wrote:
(snip)
| Quote: | The switchers I designed with non-gapped
toroids ran efficiently. The normal losses were all accounted for, such
as those in the transistor, the diode, the ESR etc. but pretty much none
in the inductor. No ringing, nice linear ramps and the cores didn't get
hot. Mostly Fair-Rite stuff.
|
Do you remember what ferrite type you used? I agree that adding gaps
increases the volume of copper needed to keep the copper losses
unchanged, but ungapped boost designs tend to use a lot of ferrite
relative to the energy being transferred. For very low power designs,
this may not be very important.
--
John Popelish |
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Guest
|
| Posted:
Tue Mar 22, 2005 6:10 am Post subject:
Re: Toroid Core for LED V Boost |
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Michael wrote:
| Quote: |
This discussion has picqued my interest. I gotta fidn some more "donuts" and
have at it.
|
Here's one: Electronic Goldmine item # G6683 - 5 for a dollar.
http://www.goldmine-elec.com/default.htm
It is a "medium sized" core - easy to work wth - it's a lot
larger than the MPJA cores.
Ed *
* |
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Guest
|
| Posted:
Tue Mar 22, 2005 6:10 am Post subject:
Re: Toroid Core for LED V Boost |
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Michael wrote:
| Quote: | I checked out a couple photo shops, hoping to get my hands on some disposable
camera flash guts as you(?) suggested, and was told at both places that they
don't toss disposables. They turn 'em in for cash. Ah well ...... some Zetex
goodies will be coming soon.
The one near me gets 25 cents per camera. At 4 for |
a buck, you can't go wrong. The AA cell alone is
worth that.
Ed |
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Joerg
Guest
|
| Posted:
Tue Mar 22, 2005 6:10 am Post subject:
Re: Toroid Core for LED V Boost |
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|
Hello John,
| Quote: | Do you remember what ferrite type you used? I agree that adding gaps
increases the volume of copper needed to keep the copper losses
unchanged, but ungapped boost designs tend to use a lot of ferrite
relative to the energy being transferred. For very low power designs,
this may not be very important.
|
Mostly 77 material and some more modern ones. Also, Kaschke K2004 and
K2006, plus some others for the 100-500kHz range. For frequencies in the
MHz range #43. Cost was usually a key factor so no boutique stuff.
Regards, Joerg
http://www.analogconsultants.com |
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Joerg
Guest
|
| Posted:
Tue Mar 22, 2005 6:10 am Post subject:
Re: Toroid Core for LED V Boost |
|
|
Hello Michael,
| Quote: | My latest booster design uses one of the rough-surface toroids (above) and the
20# wire. I put a new AA in it at 3:30 PM on Friday afternoon and it's still
running as I write this (12:21 PM), nearly 45 hours. The All Electronics bright
white LED is dim now compared to its dazzling self when the battery was fresh,
but the light is sufficient that it could be used for close-in (12" or so)
work. Transistor is a "wimpy 2N3904". 1K base resistor.
|
Sometimes a few hundred pF across that 1k can drive the base for a
snappier switching and a few more percent in efficiency. But you'd have
to calculate that for the 2N3904.
Regards, Joerg
http://www.analogconsultants.com |
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Watson A.Name - \"Watt Su
Guest
|
| Posted:
Tue Mar 22, 2005 12:50 pm Post subject:
Re: Toroid Core for LED V Boost |
|
|
"John Popelish" <jpopelish@rica.net> wrote in message
news:423E6137.576D86AD@rica.net...
| Quote: | Michael wrote:
This discussion has picqued my interest. I gotta fidn some more
"donuts" and
have at it.
Excellent! If you have trouble finding similar pairs, let me know and
I will mail you a few.
|
I found some 'donuts' - toroids on Ebay. The only problem is that
they're from a British seller, and I think the shipping costs might be
just a bit too high. They're white cores from Philips, I believe. I
did a search for ferrite -cables. The -cables is because there are a
lot of video cables and such for sale. Putting the minus to exclude
them gets the number of hits down to a reasonable size.
What I would really like to know is what were the parameters for the
..19" (ID) cores that All Electronics sold, but which are now out of
stock. I think someone said they were charcoal colored. It would be
informative is someone with a bunch of them wound ten turns of, say, 24
gauge wire on a few and measured the inductance, so we could get a good
idea of their permeability.
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Watson A.Name - \"Watt Su
Guest
|
| Posted:
Tue Mar 22, 2005 2:17 pm Post subject:
Re: Toroid Core for LED V Boost |
|
|
"Fred Art" <rajabetawi@hotmail.com> wrote in message
news:Xns962160580DA02FArt@203.26.24.228...
| Quote: | Michael <NoSpam@att.net> while reading the NewsGroups, express out
opinion in news:423E5041.AFDA3AC@att.net:
I checked out a couple photo shops, hoping to get my hands on
some disposable camera flash guts as you(?) suggested, and was
told at both places that they don't toss disposables. They turn
'em in for cash. Ah well ...... some Zetex goodies will be
coming soon.
Check out Ebay stuff like this is available.
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&rd=1&item=7501877040
&ssPageName=STRK:MESE:IT
|
The one in the pic looks pretty much the same as the ones I got.
He forgot to tell that the transistors are good for making LED V boost
circuits. :-)
Some of the toob nuts out here could use the 300VDC for their B+.
Cattle prod. Electric fence shocker. Neon light blinky supply.
Think up some more uses.
> F.Art |
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QuantSuff
Guest
|
| Posted:
Tue Mar 22, 2005 7:38 pm Post subject:
Re: Toroid Core for LED V Boost |
|
|
"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:113vfmod40vn3a@corp.supernews.com...
| Quote: |
(snip)
What I would really like to know is what were the parameters for the
.19" (ID) cores that All Electronics sold, but which are now out of
stock. I think someone said they were charcoal colored. It would be
informative is someone with a bunch of them wound ten turns of, say, 24
gauge wire on a few and measured the inductance, so we could get a good
idea of their permeability.
The last batch of the .19" I ordered were thinly-coated ferrite and gives a |
whopping 3uH per turn^2 - 10 turns of #28 (heavier wire will bind in the
tiny hole) gave around 270uH. I stacked 2 of then together and got a 3000uH
inductor with just 16 turns!
The .30"-ID one is powdered iron, and is about 55uH with 10 turns.
QS |
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Watson A.Name - \"Watt Su
Guest
|
| Posted:
Tue Mar 22, 2005 8:01 pm Post subject:
Re: Toroid Core for LED V Boost |
|
|
"John Popelish" <jpopelish@rica.net> wrote in message
news:423F8082.F395724C@rica.net...
| Quote: | Joerg wrote:
(snip)
The switchers I designed with non-gapped
toroids ran efficiently. The normal losses were all accounted for,
such
as those in the transistor, the diode, the ESR etc. but pretty much
none
in the inductor. No ringing, nice linear ramps and the cores didn't
get
hot. Mostly Fair-Rite stuff.
Do you remember what ferrite type you used? I agree that adding gaps
increases the volume of copper needed to keep the copper losses
unchanged, but ungapped boost designs tend to use a lot of ferrite
relative to the energy being transferred. For very low power designs,
this may not be very important.
|
IMHO, if it really was important, one would see these gaps in ferrite
toroids. But one doesn't.. (At least not in my experience.)
One other factor, it's a lot easier to wind a bobbin compared to a
toroid. So one does see a lot of bobbins on gapped cores. I would
think that a gapped toroid wouldn't give any better performance than a
bobbin on a gapped core, so instead of pursuing this line of thought, we
should just cut to the chase and go with bobbins and gapped cores. Pot
cores would be another alternative.
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