creating an electromagnet using my Amp / AC signal tia sal22

 

Greetings All

I have a pt1100 amp with an impedance of 8 ohms rated at about (1000
watts output power) and a toroidal electromagnet with the resistance
of about 1 ohm.  I'm doing an experiment with AC signals, audio and
toroidal coils.  I'm trying to see how much I can increase the
magnetism inside the toroidal coil basically a donut electromagnet
using AC signals.

The steps I use:
I play a signal out my computer than it's amplified by the pt1100 amp
which is connected to the wire wound around a donut shape.  Like this
http://www.codecogs.com/users/13108/img_em5.jpg

The problem I'm having is after I play the signal with about an 1 amp
running through the wire the internal circuit breaker in the pt1100
amp gets tripped.  Is there a way I can get all the amps to flow
through the wire without tripping the internal circuit breaker of the
pt1100 amp?

Please not that the goal is to get as much current to flow though the
wires of the toroidal coil as possible to create an electromagnet
without tripping the internal circuit breaker of the amp.  At the
moment I can't increase the windings.  I tried putting a ceramic
100ohm 10 watt resistor in series with the coil to see if that would
help but the change was barley noticeable .

I also tried making a glass water resistor but it looks like most of
the current was dropped in the water doing electrolysis.

And also I can't use DC at this point.

PS:  I'm using 18 gauge wire.

Tia sal22

 

On 8/21/2009 6:45 PM Rick T spake thus:


Nope.

The problem is pretty obvious, and I think you already know that you're
overloading the amp. Measure the resistance of your toroid coil: it's a
*lot* less than 1 ohm, right? You do the math, as they say.


--
Found--the gene that causes belief in genetic determinism

 


"Rick T"

** That is not any kind of 1000 watt amp.

 It is  PILE  OF  SHIT  that retails for $89.



**  Insanity.



**  Duuhhh  !!

  Amazing it has not yet blown up.



**  Insanity.


**  Be of no help with toroid.




.....  Phil

 

In article


The amplifier you mentioned cannot deliver a "thousand-watt" output;
that's what it's capable of at the *peaks* of an audio signal, into
certain loads. It's probably less than half that continuous.


For AC signals, what's important is not resistance, but impedance.

And that amp almost certainly cannot deliver anything like 300 to 400
watts into a one-ohm load. Audio amps are almost always limited in power
output by the amount of current they can deliver (so if whatever the
current is, can drive 400 watts into 8 ohms, it can only deliver 1/8 of
that power *at most* into one ohm, because the current will be the same.


Using a coil constructed according to that drawing, the magnetic flux
will be confined to the iron core. Did you expect to have a (powerful)
field in the "hole"? Because that won't happen. Toroids are preferred as
cores for coils and transformers *specifically because* they confine
magnetic fields better than other topologies.

What did you want/expect to happen here?


It's probable that you need either more turns or a higher frequency
(assuming the amp can handle that).


The way to maximize current *using the amp you mentioned* is to get
enough wire on the toroid to make the load look like eight ohms (and
note that's *impedance*, not just resistance. And, you have to make sure
the wire you use has a large enough cross-section to handle that amount
of current (probably seven or eight amps *if everything works out*). The
next issue will be to make sure you don't saturate the toroid (ask it to
carry a larger magnetic field than it's capable of).

As I said, even if you get a lot of current to flow, there will be no
*external* magnetic field, possibly except for a bit of leakage.


A series resistor may stop the breaker from tripping, but it will do
that by limiting the current, which is counterproductive if you want a
powerful field (the strength of which is proportional to the current
times the number of turns on your coil).


That would not produce an external field either.


The wire gauge is not first-order important here. It just gives you a
clue as to how much current might produce how much heating at some
specific frequency.

If you're genuinely interested in pursuing this project, I suggest you
do a bit of reading. Start with the relationships of resistqnce,
reactance, and impedance -- what they are, and how they are measured;
check into magnetic saturation and why it's a good idea to avoid it;
learn what the specs of that amplifier *really mean*, so you'll
understand just how much current it can actually deliver (at different
frequencies). Then you'll be much better equipped to get something
working that does what you want it to.

Isaac

 



**BZZZZTT! Wrong. Given the abscence of real specs, I would guess that your
amp can deliver no more than 50 Watts/channel.

 and a toroidal electromagnet with the resistance

**Define "toroidal electromagnet". Electromagnets are NEVER toroidals. Are
you attempting to use a toroidal transformer as an electromagnet? You are
doomed to fail.

  I'm doing an experiment with AC signals, audio and

**Why? What frequency?

  I'm trying to see how much I can increase the

**Won't work with AC signals. Go read a text book on the subject.


**That is not an electromagnet. It is a simple inductor.


**You probably already are. Your pitifully crappy amplifier does not like
the abuse.


**Then stop wasting your time. Go study some texts on the subject.


**Doesn't matter what you are using. Whatever you're trying to do is doomed
to fail. Well, unless you want to destroy your POS amplifier. On that
aspect, you are on track to succeed.


--
Trevor Wilson
www.rageaudio.com.au