SatCure ferrite beads for single AA LED

Joined
Mar 15, 2001
Messages
598
Location
Ohio
Hey all. Let's use this topic to send in your requests (to me) for ferrite beads from Martin at SatCure.
He is sending 100 of them to me (through KenBar) and I will be sending them to folks who want them.
Once I get the beads I will find out how much postage will be. Can't be much.
wink.gif

Leave a message here with how many you want, and email me your shipping address.

My email is correct when you click on it in the topic header.

I'll post updates here to let you know when they get here, how many are still available, etc...
 
Joined
Mar 15, 2001
Messages
598
Location
Ohio
Here's a link to the circuit we're talking about.
http://www.netcentral.co.uk/satcure/design/microtor.htm

I've talked to Martin and here was his reply:

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR> These ferrite beads cost only pennies
blush.gif


What I'll do is to post 100 to Ken on (hopefully) Tuesday. You can all
then fight amongst yourselves
blush.gif


The wire is 38SWG or 0.0060". I don't know what this is in AWG but I'm
sure you can find out. The stuff I use is polyurethane coated. You need a
90cm length. That's a yard. You fold it in half and thread the folded end
through the bead until only two 1.5 inch tails remain. Then thread the
folded end through the bead another 19 to 20 times. Finally, snip the
folded end so you have four wires. Measure them for continuity so you can
pair them and solder two non-connected ends together. Take care when you
"tin" the ends because the urethane gives off poisonous fumes.

The resistor is 10k. You can reduce this to 2K which will increase the
*average* LED current from 18mA to 30mA - more than enough for a
hyperbright LED! Obviously, if you decide to use a PNP transistor, you
have to reverse the LED and battery connections. The physical size of
this circuit is tiny. I used a surface mount resitor, cut the transistor
leads real short and mounted the whole thing inside my old General Motors
car key *instead* of the existing bulb!! The most efficient transistor is
the ZTX650. Other transistors work but at reduced efficiency. A ZTX650
gives 79 percent efficiency, a ZTX450 73 percent and a BC550 57 percent.

I have used four white LEDs in series. These ran at full brightness for
12 hours off a 1.5v mercury "button" cell. For the next 12 hours the
brightness gradually reduced. Of course, you could run it off one or two
"D" cells (large torch cells) and it would run for weeks.

If you can club together to send me $20 for the beads then I'll be happy.
I can also supply the wire and transistors, if required. You have till
Monday night to decide.

I get the white LEDs from **** Smith Electronics in Australia. You could
club together to make up an order and pay by credit card to save time. (I
can't accept credit cards yet).

Well, I won't make much profit from this but I'm just pleased to see
people actually interested in Electronics. There aren't many of us left.
Most people nowadays think it's essential to use a microcontroller or a
PIC to make even a simple oscillator!

Kind Regards,

Martin

Martin T. Pickering B.Eng.
<HR></BLOCKQUOTE>

I will send Martin $20 and KenBar whatever it costs for him to ship 100 beads to me here in Indiana.
Then I will offer the beads "at cost" plus shipping to anyone interested.

Hope this helps to inspire some neat new LED lights!
 
D

**DONOTDELETE**

Guest
Hi Gadget,

You can put me down for five of the ferrite beads. I've sent you e-mail with my request and my address. Thanks. This should be fun.
grin.gif


Mark
smile.gif
 
Joined
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Messages
598
Location
Ohio
Ah, OK Ken, I got your email, but didn't see the post here.

Disregard the email I sent about postage then.
tongue.gif


And yeah, this should be pretty neat.

Anyone finds a decent source of wire, let us all know!

Mark, I got your email and you are entered into my Mailing List that I'll use when the time comes.

As for R1, Martin's email said we could reduce R1 from 10K to 2K to increase the current to about 30ma. Don't know how low you can go before the oscillator quits though... May have to do some experimenting to find out.
smile.gif
 
Joined
Mar 15, 2001
Messages
598
Location
Ohio
Ed, Thanks!
Believe it or not, I was there checking pricing when I saw your post!
smile.gif


Unfortunately, they want $14.50 for a $6.50 spool after shipping and handling!

I'll check my local electronics store tomorrow and see what they have (or can get). They are NOT a radio Shack. They have tons of components and "tinkering" supplies.

Hopefully, I can get the wire before the beads come in. Then I can just sell the wire with the beads and make everyones life easier.
wink.gif


You interested in some beads to build your own 1AA LED light?
 
Joined
Mar 15, 2001
Messages
598
Location
Ohio
LOL Ken!

That's why I always refresh before posting.
smile.gif
Even then, it still happens sometimes!

I think Hutch & Sons (my local source) will have what we need. I'll go tomorrow and let you all know what I find. From what I have seen on the web, a 1/4lb spool of 34AWG will have approx. 2000 feet on it. That's enough for 667 ferrite beads! LOL!

I don't wanna be taking away from Martin's business any though. I asked him to let me know if we were overstepping our use of his information and generosity.

Thanks again Martin!
grin.gif
 

Badbeams3

Flashlight Enthusiast
Joined
Sep 28, 2000
Messages
4,389
Would it be possible to package everything into a PR base. I`m thinking it would be nice to have a white "bulb" that would fit into standard 2 cell lights. It may not require as many windings as a single battery step up. LED corp. was going to do this but backed out on the belief that not to many people would be interested. I disagree.
 
Joined
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Messages
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Location
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I too think that the parts won't fit in a PR base. You've got the transistor, resistor, and the coil (which we still don't know how big it is). Gonna be an awful tight fit.
confused.gif

But KenBar's ideas are both excellent.
smile.gif


Either build a dummy cell, or find some room behind the reflector. I personally like the second option best. That way you have 2 batteries in there working. I assume the circuit will also work on 3v input.
smile.gif


Also, I'm beginning to think that it would be a lot easier to just team up and order kits from Martin.
smile.gif


I found some 36 gage wire today. All they had was 1/2lb spools though. So for $24, I got 8,000 feet of AWG36 wire.
shocked.gif


Maybe I'll build a Tesla coil...
 
D

**DONOTDELETE**

Guest
I just found a USA company that has the beads, took about 3 weeks but now I have 300 on the way, should be here next week!
 

X-CalBR8

Flashlight Enthusiast
Joined
Apr 14, 2001
Messages
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Location
TN, USA
Hi. I just read that you guys were looking for some "enamel coated" wire to make this circuit. This is the same wire that is used to make the windings on many small motors, so if you want to get some cheap wire for this project, then just cannibalize an old kids toy for it. Also Radio Shack carries this wire for sure, but who wants to be ripped off by their prices. I hope this info helps someone. Btw, this sounds like a really neat project from what I've read.
 
Joined
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Messages
598
Location
Ohio
I have received the beads from Satcure (by way of KenBar). I will be sending them out to those who contacted me.
I should have several left if anyone else wants to play with them.
wink.gif

These are the "real" Satcure beads, but there are others that work.
wink.gif


I also have plenty of enamel coated wire. It is slightly smaller than what Satcure recommends, but it does work. In addition, the smaller wire allows more turns to be put on the bead, if you want to "tinker".

Feel free to email me if you are interested. I'll be contacting those on my "mailing list" soon.
 

Coherence

Newly Enlightened
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Location
Bend, Oregon
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR> I currently have it running with a mercury switch robbed off an old Honeywell thermostat.

It turns on when I point it parallel or down...Not much good for looking for spiders on the ceiling however... <HR></BLOCKQUOTE>


I have played with mercury switches too. Haven't yet come up with a scheme that works well for a flashlight though (think about putting 2 or more switches in parallel, or series for that matter).

However...

Another alternative switch is the magnetic reed switch. I just took apart a sensor that is used for home security (attaches to a window). Inside is a magnetic reed switch with both normally open and normally closed contacts. If you bring a magnet within an inch or two of it the switch flips.

I want a light that is truly waterproof and easy to turn on/off. What I have found is that the weak point in being waterproof seems to be the switch. The switches that really are waterproof require two hands to use (twist the O-ringed head down until it lights).

My thought is to build a flashlight where the light is 'on' by default. Also make a holster with a magnet in the appropriate place.

Now you have a light which:
1. Is always on when you use it.
2. Lights up if you drop it or are separated from the light.
3. You are 'reminded' to return it to its holster (the only way to turn it off). Now you can find it later, it is on your belt.
4. *Nothing* protrudes through the case to allow water leakage.

Anyway, just a thought.

Incidently the magnetic switch is a cylinder about 1/2" long and 1/8" diameter.

Update: it will work through the wall of a 3D cell Maglight, i.e. sensor on one side and magnet on the other. So aluminum flashlight is certainly possible w/magnetic switch...

also a simple deactivator switch would be a rubber band with a magnet glued to it to fit around the body of light.
 

Steelwolf

Flashlight Enthusiast
Joined
Feb 6, 2001
Messages
1,208
Location
Perth, Western Australia
I was just thinking (and that is a dangerous statement all in itself
grin.gif
) that since I was able to find the ferrite core in **** Smith's Electronics, you might be able to find it (if you search hard enough, like I did
tongue.gif
) in your local Radio Shack.

Just my 2cts worth... wait, better make that 4cts, cause I need to say that although it is a very cool circuit as is, the addition of a bridge rectifier will boost the output tremendously, and probably save your LED from "burning" out.
 

Steelwolf

Flashlight Enthusiast
Joined
Feb 6, 2001
Messages
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Location
Perth, Western Australia
For more information about why the bridge rectifier was put in, see the other post. Suffice to say, there is quite a huge amount of back EMF and the bridge rectifier converts it all to forward voltage/current. I didn't put it in at first and burnt out one LED.
 
Joined
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Messages
598
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Ohio
I haven't had a chance to put it on an oscilloscope yet, but the way the circuit is designed, there should be no reverse voltage through the LED at all.

Should only be a pulsed DC voltage going through the LED. I can't even begin to figure how it could blow an LED... Mine isn't all that bright.

From what I can tell about how the circuit functions, it's much like a car's spark plug coil. The transistor oscillates OFF and ON. When its ON, it puts current through the coil (one side) while shorting out the LED. When it shuts OFF, the field in the coil collapses and generates a high voltage spike (DC). The only path for it the get to ground is through the LED. I've measured the "duty cycle" of several resistor variations and it's always very close to 50%. In other words, 50% ON, 50% OFF.

Once I catch up on all my school work and projects (like mailing out these beads), I'll take it to school and hook it up to an oscilloscope. See what's going on in there.
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