Shorting coil gives back more power

[hartiberlin]

Hi All,
you can use also some kind of this circuit.

If the voltage for the coil is produced by induction from a magnet
or via a running current from a battery does not matter much.

The toggle switch can be toggled all the time and you could also use
a "selftoggling" relay for this ( like a doorbell ringer circuit).

You can also use a MOSFET, but then you might not have the Newman
effects of the mechanical switching, which might put back current spikes
back to the battery and recharge it automatically.

Regards, Stefan.

[hartiberlin]

P.S. Interesting will be to see,
what kind of effect this 1 uF cap will have.
You can also try 10 uF or 100 uF.
Should be NO electrolyte cap but a foil cap.

Maybe you should also short it out, so it is
not in the circuit.
Maybe it will reduce the current draw from the battery,
but the voltage spikes might be lower, if it is in the circuit.

Watch out, that you don´t overcharge the 1000 uF 350 Volts
output electrolytic cap, as it could explode when having too much voltage.

Always have a voltmeter and also better a load resistor across it.
If it goes over 300 Volts always stop the circuit and discharge the cap.

Be very cautious.
300 Volts at 1000 uF can easily KILL YOU on the first touch !

So I take NO responsability of your actions !

Always wear rubber gloves when working with high voltage DC
circuits and use only one hand to touch the circuit and only use the
right hand ( not the left one, where your heart is...! put your left hand in your trousers pocket !)

Also wear good isolating rubber sole shoes. Never experiment with standing just with bare feet
on the ground !

Good luck !
Regards, Stefan.

[Magluvin]

Hi All,
you can use also some kind of this circuit.

If the voltage for the coil is produced by induction from a magnet
or via a running current from a battery does not matter much.

The toggle switch can be toggled all the time and you could also use
a "selftoggling" relay for this ( like a doorbell ringer circuit).

You can also use a MOSFET, but then you might not have the Newman
effects of the mechanical switching, which might put back current spikes
back to the battery and recharge it automatically.

Regards, Stefan.

Wow   wouldnt that be a lot of constant current on the MOT? Are you sure it is on the right side of the switch?   Just asking and maybe you have a good idea here, just never seen it that way. =]

Mags

[teslaalset]

The example of Stefan seems confusing to me.

In this example the coil is powered by an external voltage source. Imagine the voltage source is AC.
If a sinus shaped voltage over the coil is used, the current through the coil is 90 degrees lagging.
If a coil is shorterned at the peak of the voltage, therefore there is no current flow at in the coil yet.
Using E_coil= 0.5LI^2, this means no energy is stored in the coil at the moment the coil is shortened.

I think it is only the case when flux is generated by a magnet.
So, shortening coils at maximum voltage should apply to generator situations, not motor situations?

Basics:
Flux is proportional to current in the coil
EMF is proportional to the delta flux in the coil and therefore proportional to delta current
If a coil is to be shortened at max EMF, the delta current is max.
Delta current is max when it crosses zero amps
With zero amps there is no energy left in an 'air coil'.
So, if there is an effect, this should be related to magnetic viscosity of core material.
Using air coils does not make sense to me.
Any other opinions?

[hartiberlin]

The example of Stefan seems confusing to me.

In this example the coil is powered by an external voltage source. Imagine the voltage source is AC.

Hi teslaalset,
your arguments do not apply, cause it is a pure DC current that powers the coil in my
case.
The DC current is just chopped via the switching.

It has to be tested, could be, that I am wrong, but that must be tested.
Also please test, if adding a permanent magnet onto the coil
or onto the MOT core does have any effect on the output.

It must also be tested, if it will work better with iron core coils
or just air core coils.
With air core coils you can probably go to higher switching frequencies.

Regarding the high voltage requirements Ismael mentioned,
it would be good to also use a high voltage power source instead the
12 Volt battery and just switch this via the resistor onto the coil
only for a few milliseconds and then switch it off again.
But then you need more complex switches and high voltage
switches, which are much more complicated.

Just try it first this way as I have posted it .

Many thanks.

Regards, Stefan.