Maker Pro
Maker Pro

Ferrite Rods (or work alikes)

P

phaeton

Jan 1, 1970
0
This looks like a pretty cool circuit:

http://www.redcircuits.com/Page55.htm

However, where would I purchase a set of ferrite rods? I checked
Jameco and Radio Shack, but no dice.

-or-

Would any ferrous metal rod work similarly? I.e. a simple steel nail
or bolt?


-and-

Anyone ever build this? Would increasing the voltage increase the
range?

thx
 
P

Phil Allison

Jan 1, 1970
0
"phaeton"
This looks like a pretty cool circuit:

http://www.redcircuits.com/Page55.htm

However, where would I purchase a set of ferrite rods? I checked
Jameco and Radio Shack, but no dice.

-or-

Would any ferrous metal rod work similarly? I.e. a simple steel nail
or bolt?


** No, must be ferrite.

Get then nothing out of any discarded transistor radio, cassette radio or
clock radio.




......... Phil
 
D

default

Jan 1, 1970
0
This looks like a pretty cool circuit:

http://www.redcircuits.com/Page55.htm

However, where would I purchase a set of ferrite rods? I checked
Jameco and Radio Shack, but no dice.

-or-

Would any ferrous metal rod work similarly? I.e. a simple steel nail
or bolt?


-and-

Anyone ever build this? Would increasing the voltage increase the
range?

thx
A bolt probably won't work. Eddy currents in the bolt would eat up a
lot of the energy making the range low assuming the transmitter
portion oscillated at all.

You do have some options however. Assuming you can't find some
ferrite rod material, you can stack a series of toroids or ferrite
beads together and treat it like a rod (use a dowel or nonconductive
center or just glue them together)

It oscillates at 35 KHZ which is relatively low and you could probably
get by with a bunch of thin iron wire. The iron should not conduct
well, so allow it to rust a little before packing the core.

I use steel fence (agricultural electric fence) wire for wire cores
since it is readily available and cheap. It is zinc coated to prevent
rusting and is very conductive. I cut the wires to the length I need
for my core then put them in a jar of vinegar for a few days - that
causes the zinc to oxidize and insulates the wires. I neutralize the
acid with a rinse of baking soda.

Craft stores are another source of thinner steel wire - but they can
be costly if you need a large core.

Alternatively you can just chuck them in a fire and burn the coating
off - the zinc vapor may be toxic so you'd want to avoid doing it
where you breath or under the chicken in the BBQ grill . . . Burning
it will or may cause it to anneal and that is desirable in a magnetic
core (easier to bend or straighten too)

You can make your own powdered iron cores that will work really well.
I started fooling with steel wool in an attempt to make a high
frequency core - it actually worked pretty well.

You can make a core to rival commercial ones by buying fine iron
powder - stay away from science shops, it costs too much - it is for
sale on line for pyrotechnic purposes in different sieve numbers
(particle sizes). Stuff is used to make bright white star burst
fireworks shells and roman candles.

My technique is to mix the powdered iron with epoxy thinned with a
smidgen of acetone (or get thin boat builders epoxy or polyester
resin) then pour it into a short length of PVC or CPVC pipe that has
been waxed inside with a coating of silicon grease as a mold release.

Pour it and cap it on both ends with greased PVC end caps pushed on,
store it vertically while the epoxy sets - or you will regret it - one
end cap will leave a shoulder in the molded product - it won't come
out from that side. Let harden for a day or two then push the iron
out (a dip in a pan of boiling water will help if it doesn't just
slide out - most won't with PVC, CPVC is smoother inside).

Voilà! a powdered iron core that didn't cost a mint.

A further refinement is to stack ring type ferrite magnets around the
mold while it hardens (stack has to be full length and you may have to
grind off the shoulder on top before you push it out)

I have a lot of old speaker magnets that work well for that - but
winding a coil and passing current through it may also work.

Magnets increase the permeability of the core by aligning the
particles of iron while it sets up. They also tend to cause the
mixture inside to try to walk out of the tube - so be sure to use two
end caps pushed on hard.

It may work to just stuff a tube with iron powder and glue the caps on
- I don't know. The wall thickness of the tube may work against you
for leakage inductance and the particles may move around while being
excited by the driver - I assume that would be a bad thing but I
haven't tried it.

cool circuit - haven't built it
 
J

jasen

Jan 1, 1970
0
I use steel fence (agricultural electric fence) wire for wire cores
since it is readily available and cheap. It is zinc coated to prevent
rusting and is very conductive. I cut the wires to the length I need
for my core then put them in a jar of vinegar for a few days - that
causes the zinc to oxidize and insulates the wires. I neutralize the
acid with a rinse of baking soda.

Fence wire is high-tensile, I'd expect softer wire, like tie wire to
work better.

pre-rusted tie wire can be had cheap at places that sell steel for
concrete reinforcing.

a coating of lacquer may work better than just trusting the rust to
insulate it.

To straigtten short lengths of wire roll them between two flat MDF boards.

Bye.
Jasen
 
H

Homer J Simpson

Jan 1, 1970
0
However, where would I purchase a set of ferrite rods? I checked
Jameco and Radio Shack, but no dice.

Buy cheap radios from Wal-Mart and rob parts from them.
 
D

default

Jan 1, 1970
0
Fence wire is high-tensile, I'd expect softer wire, like tie wire to
work better.

pre-rusted tie wire can be had cheap at places that sell steel for
concrete reinforcing.

a coating of lacquer may work better than just trusting the rust to
insulate it.

To straigtten short lengths of wire roll them between two flat MDF boards.

Bye.
Jasen

Yeah, annealed (soft) wire is better for transformer hysteresis.
Leaving it in the charcoal grill and shutting the vents to kill the
fire works like a champ to anneal, remove the zinc, and oxidize it .

Easier to work with the stiff wire if one is stuffing a tube to
capacity. Likewise, uncoated or oiled wire is easier to pack than
varnished wire.

Tie wire sounds good, I have to check that out. Bailing wire is
pre-rusted or has a black oxide coating from the factory - but who
needs 80 pound coils of the stuff? Fence wire is only $5 for a 1/4
mile and there must be ten-fifteen pounds on the spools. Really handy
around the house too.

Back when I was experimenting with induction coil cores, I stretched
the wire between trees with a come-along (cable hoist) and ran a
series of offset pulleys up and down the wire - that straightened it
pretty well. You can also buy wire for suspended ceiling "T" bar in
bundles of straight lengths 10 feet long.

My first attempt at powdered iron was to feed steel wool through a
hammer mill style garden leaf shredder. What a fiasco! It worked
but tended to "pill" clumps of compressed wool. You wouldn't believe
how far the stuff travels - the next day the clothes I wore and side
of the house and deck had rust stains.
 
P

phaeton

Jan 1, 1970
0
Excellent, you guys.

As far as using wire to make an inductor, how about putting pieces in
a plastic drinking straw for insulation? Work? No?

As far as epoxying a bunch of beads together, does there need to be
anything in the middle of them? Maybe just a plastic bolt to mount
them somewhere with?

Now (the big question)

Which has a higher effect on the 'coarse tuning' of the inductor:

1) Number of turns of wire.
2) Length of ferrite core.
3) Diameter of ferrite core.
4) Other

I realize that radios are 'fine tuned' with a variable capacitor. I
know this is also not a very simple answer, so pointers to data is
appreciated.

Also, the transmitter circuit calls for 3V-9V operation. If I were to
modify the circuit for 18V-24V operation, would that increase its
range?

Thanks!

-phaeton
 
J

John Popelish

Jan 1, 1970
0
phaeton said:
Excellent, you guys.

As far as using wire to make an inductor, how about putting pieces in
a plastic drinking straw for insulation? Work? No?

Sure, but not really needed. The ferrite is not a very good
conductor. and the signal voltage is low, so the wire
insulation is plenty.
As far as epoxying a bunch of beads together, does there need to be
anything in the middle of them? Maybe just a plastic bolt to mount
them somewhere with?

Nothing needed, but almost anything will work. Even a metal
bolt, since most of the flux will pass parallel to it
through the ferrite.
Now (the big question)

Which has a higher effect on the 'coarse tuning' of the inductor:

1) Number of turns of wire.

Proportional to almost turns squared, for turns in the
middle third of the rod.
2) Length of ferrite core.

Almost proportional to length.
3) Diameter of ferrite core.

Less than proportional.

Location of turns on rod. Higher inductance for turns near
center of rod, so fine adjustment by sliding the rod off center.
I realize that radios are 'fine tuned' with a variable capacitor. I
know this is also not a very simple answer, so pointers to data is
appreciated.

Also, the transmitter circuit calls for 3V-9V operation. If I were to
modify the circuit for 18V-24V operation, would that increase its
range?

If nothing burned up, probably. I would go with a longer
rod, though.
 
P

Phil Allison

Jan 1, 1970
0
"John Popelish"
phaeton wrote:

Sure, but not really needed. The ferrite is not a very good conductor.
and the signal voltage is low, so the wire insulation is plenty.


** You have completely misconstrued the OP's words.

Tell the PITA troll to get his ferrite rods from old radio and shut the
**** up.




........ Phil
 
J

John Popelish

Jan 1, 1970
0
Phil said:
"John Popelish"


** You have completely misconstrued the OP's words.

Tell the PITA troll to get his ferrite rods from old radio and shut the
**** up.

Sorry to hear about the pain in your ass.

Mine feels just fine.
 
P

Phil Allison

Jan 1, 1970
0
"John Popelish"
Sorry to hear about the pain in your ass.


** Misconstruing is your only forte.

Piss head.



......... Phil
 
J

John Popelish

Jan 1, 1970
0
Phil said:
"John Popelish"


** Misconstruing is your only forte.

Piss head.

At least I'm good at something.

By the way, do you care to tell why you are so angry so much
of the time? Are you here to because you are angry, or in
spite of being angry?
 
P

Phil Allison

Jan 1, 1970
0
"John Popelish"
At least I'm good at something.


** Misconstruing is your only forte.

Piss head.

By the way,


** Misconstruing is your only forte.

Piss head.

do you care to tell why you are so angry so much of the time?


** Misconstruing is your only forte.

Piss head.

So fuuuuck the hell off.



........ Phil
 
P

Phil Allison

Jan 1, 1970
0
"John Popelish"
Phil Allison wrote:


Get used to disappointment.


** Misconstruing is your only forte.

Piss head.

You'll be dead soon.




........ Phil
 
J

John Popelish

Jan 1, 1970
0
Phil said:
"John Popelish"


** Misconstruing is your only forte.

Piss head.

You'll be dead soon.

Of course, as shall we all.
 
L

Lord Garth

Jan 1, 1970
0
John Popelish said:
Of course, as shall we all.

I'm surprised you haven't placed Phil in your ignore list John....

I never see anything from him unless it's copied.
 
J

John Popelish

Jan 1, 1970
0
Lord said:
I'm surprised you haven't placed Phil in your ignore list John....

I never see anything from him unless it's copied.

I can't turn away from train wrecks, either.
 
P

Phil Allison

Jan 1, 1970
0
"Lord Garth"


** Bugger off - you worthless tenth wit.





....... Phil
 
L

Lord Garth

Jan 1, 1970
0
John Popelish said:
I can't turn away from train wrecks, either.

You do well not letting him pull you down to his level.

The guy tried to tell me what I had found inside of a no name
wall wart in 1979! It was then I added him to my short list of
ignores. Funny thing is, that wall wart and the digital clock it's
attached too, are still operating today. The chip is a Mostek 50250.
 
Top