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When you think through the analogy you present here, you find that by
doubling voltage and halving current, you get EXACTLY the same results. The
coil with both halves in series (i.e. the normal winding, not the bifilar
one) has four times the resistance of the bifilar one, since the coil halves
are in series rather than in parallel. Also, since the number of turns is
double (of the bifilar), the inductance is quadruple (L being proportional
to turns squared). If you double voltage, the rate of rise of current is
still only half (since L is 4x) but the current you wish to achieve is also
only half (since double turns) to achieve the same magnetic field. Hence
the time constant is exactly the same. The same rationale holds for
resistance. There really is no difference; it is just a matter of changing
the impedance of the power supply to match that of the coil. Simple
transformer action.
Peter Boetzkes
----Original Message Follows----
From: [email protected]
Reply-To: "The Proton Mag Forum"
To: The Proton Mag Forum
Subject: Re: Bifilar windings
Date: Fri, 19 May 2000 13:08:38 +0100
The Proton Mag ForumI think this approach also has some merits too.
Certainly increasing windings and increasing polarizaton voltage should
if done proportionatly keep the flux induced in the core the same, whilst
decreasing copper losses due through resistive loss in the windings. And
as a result of having more windings you should increase the signal pickup.
There are some other factors to consider in this arangment.
Increasing the windings increases the inductance of the coil and there
fore impedence of the coil. (Impedance is to AC what pure resistance is
to DC, but is a fictional effect that reflects the sum of the interactive
effects that come into play as soon as you allow emf to vary.) The net
effect should be to increase the time constants associated with
establishing the polarizing magnetic field and the time taken for it to
collapse suficiently for our measurments to be taken. (Be glad to take
advice here, my AC theory is'nt that good, too much math)
I guess I am assuming that we are creating no more of a polarizing field
than is absolutely neccesary to do the job.
Think of the Coil as being a bath tub and where the coil stores
electrical ebergy as a magnetic field the bath tub stores mains water as
bath water. (Water is water, Energy is Energy).
In filling the bath you do it through a pipe of a given diameter (Coil
winding diameter) at a given presure (Voltage) and flow rate (Current).
Unlike the bath analogy when you turn off the water supply it must all
rush out again, magnetic coils are dynamic storage mechanisms. If you try
to prevent it the presure will increas until something gives. (ie the
voltage increases until it can conduct through something, When switched
through relay contacts this is what causes the sparking or arcing). The
same feature is put to good effect in joke electric shock machines.
Fill the bath through a thinner hose at higher pressure. OK but it takes
longer to do. And when emptying the same effect.
The essential question is....
Does the increase of polarizing time constant for either technique
applied to a given arrangemnt significantly cut into the preciously short
decay period.
The real aim of the game is....
To get access to as much of the decay period as we can (extend through
proton source, maximise sig to noise etc)& polarize only when neccesary
(max power efficency in a mobile set).
I am also assuming that you can not realy tap off a usable signal from
the discharging polarization coil.
I think the man with the plan vis a vis magentics must be Jim K. His math
and grip of the subject far surpases mine.
Out of interest has anyone got a storage scope and captured the out put
from a magnetometer sensor ?????
Hope this helps.
Cheers
Le Kirby
> I also
> think that, if you consider winding-switching to maximize
> polarizing
> current, you would be better off using the same circuit elements
> (controls,
> transistors, etc) to generating the optimal voltage and current to
> discharge
> into the simple monofilar coil. After all, if you double voltage
> and halve
> current, you are precisely at the same polarizing efficacy. A
> voltage
> converter feeding a suitable capacitive storage bank should do.
>
> Best regards,
> Peter Boetzkes
This message was sent by Easymail - http://www.easynet.co.uk/
__________________________________________________ ____________________
doubling voltage and halving current, you get EXACTLY the same results. The
coil with both halves in series (i.e. the normal winding, not the bifilar
one) has four times the resistance of the bifilar one, since the coil halves
are in series rather than in parallel. Also, since the number of turns is
double (of the bifilar), the inductance is quadruple (L being proportional
to turns squared). If you double voltage, the rate of rise of current is
still only half (since L is 4x) but the current you wish to achieve is also
only half (since double turns) to achieve the same magnetic field. Hence
the time constant is exactly the same. The same rationale holds for
resistance. There really is no difference; it is just a matter of changing
the impedance of the power supply to match that of the coil. Simple
transformer action.
Peter Boetzkes
----Original Message Follows----
From: [email protected]
Reply-To: "The Proton Mag Forum"
To: The Proton Mag Forum
Subject: Re: Bifilar windings
Date: Fri, 19 May 2000 13:08:38 +0100
The Proton Mag ForumI think this approach also has some merits too.
Certainly increasing windings and increasing polarizaton voltage should
if done proportionatly keep the flux induced in the core the same, whilst
decreasing copper losses due through resistive loss in the windings. And
as a result of having more windings you should increase the signal pickup.
There are some other factors to consider in this arangment.
Increasing the windings increases the inductance of the coil and there
fore impedence of the coil. (Impedance is to AC what pure resistance is
to DC, but is a fictional effect that reflects the sum of the interactive
effects that come into play as soon as you allow emf to vary.) The net
effect should be to increase the time constants associated with
establishing the polarizing magnetic field and the time taken for it to
collapse suficiently for our measurments to be taken. (Be glad to take
advice here, my AC theory is'nt that good, too much math)
I guess I am assuming that we are creating no more of a polarizing field
than is absolutely neccesary to do the job.
Think of the Coil as being a bath tub and where the coil stores
electrical ebergy as a magnetic field the bath tub stores mains water as
bath water. (Water is water, Energy is Energy).
In filling the bath you do it through a pipe of a given diameter (Coil
winding diameter) at a given presure (Voltage) and flow rate (Current).
Unlike the bath analogy when you turn off the water supply it must all
rush out again, magnetic coils are dynamic storage mechanisms. If you try
to prevent it the presure will increas until something gives. (ie the
voltage increases until it can conduct through something, When switched
through relay contacts this is what causes the sparking or arcing). The
same feature is put to good effect in joke electric shock machines.
Fill the bath through a thinner hose at higher pressure. OK but it takes
longer to do. And when emptying the same effect.
The essential question is....
Does the increase of polarizing time constant for either technique
applied to a given arrangemnt significantly cut into the preciously short
decay period.
The real aim of the game is....
To get access to as much of the decay period as we can (extend through
proton source, maximise sig to noise etc)& polarize only when neccesary
(max power efficency in a mobile set).
I am also assuming that you can not realy tap off a usable signal from
the discharging polarization coil.
I think the man with the plan vis a vis magentics must be Jim K. His math
and grip of the subject far surpases mine.
Out of interest has anyone got a storage scope and captured the out put
from a magnetometer sensor ?????
Hope this helps.
Cheers
Le Kirby
> I also
> think that, if you consider winding-switching to maximize
> polarizing
> current, you would be better off using the same circuit elements
> (controls,
> transistors, etc) to generating the optimal voltage and current to
> discharge
> into the simple monofilar coil. After all, if you double voltage
> and halve
> current, you are precisely at the same polarizing efficacy. A
> voltage
> converter feeding a suitable capacitive storage bank should do.
>
> Best regards,
> Peter Boetzkes
This message was sent by Easymail - http://www.easynet.co.uk/
__________________________________________________ ____________________