HV (bemf) Spikes - What to do with them?

[mondrasek]

@Paul-R,

As Gyula concluded, the motor is a very small brushless (I think) pager motor from a toy helicopter.  I believe it is runs on 5V in the original toy.

Just thought I'd add this fact that I omitted in the original post.  I did not know it could be relavant.

Thanks to all for the replies.  Looks like I have some more reading assignments.  Much appreciated.

M.

PS.  I'm still curious why my 8.4 V rated NiCds now charge to 9.7 V after being HV spike conditioned if anyone knows. 

[mondrasek]

@ Gyula,

Ah, Erfinder and Grumpy's posts are always an enlightening read.

So to equate to a mechanical system:  The HV spikes are like a short pulsing high pressure puff of air.  The motor is a windmill.  If they interact, the windmill sees only pulsing high pressure puffs of air.  It will move very slightly with each puff, but be stopped by friction and thus never accelerate enough to spin freely.

The cap is like an air pressure resevoir, only of incredibly tiny volume.  When the puffs of air are introduced to it the pressure builds very high rather quickly.  But the volume is so small that there is still not alot of air in there.  So when it is released into the windmill the windmill sees a slighly longer pulse of much higher pressure.  The windmill spins up higher for a split second and then slows back to a stop due to friction.

Does this sound right so far?

[Moab]

yupp keep going

@ Gyula,

Ah, Erfinder and Grumpy's posts are always an enlightening read.

So to equate to a mechanical system:  The HV spikes are like a short pulsing high pressure puff of air.  The motor is a windmill.  If they interact, the windmill sees only pulsing high pressure puffs of air.  It will move very slightly with each puff, but be stopped by friction and thus never accelerate enough to spin freely.

The cap is like an air pressure resevoir, only of incredibly tiny volume.  When the puffs of air are introduced to it the pressure builds very high rather quickly.  But the volume is so small that there is still not alot of air in there.  So when it is released into the windmill the windmill sees a slighly longer pulse of much higher pressure.  The windmill spins up higher for a split second and then slows back to a stop due to friction.

Does this sound right so far?

[mondrasek]

The high pressure air pulse from the reservoir to the windmill (case where the cap is charged and then allowed to release into the motor) can create (impart?) inertia in the windmill.  The high pressure puffs of air (HV spikes alone) cannot. 

I'm not entirely clear on why.   Have I fallen or skipped off course?

Is this analogous to the stationary wave concept?

M

[sparks]

    A resonant circuit can be analogous to the below:

Two air compressor tanks form the capacitor plates.  An air motor/pump  with an attached Flywheel the inductor.   The motor is connected between the two tanks.  One tank is full of compressed air the other empty.  The capacitor is charged.  We open the valve and the air pressure flows to the motor but the flow is resisted by the flywheel.  The pressure slowly accelerates the flywheel with an increase in flow/current.  Meanwhile the tanks are approaching equal pressure differential.  The flow does not stop after the pressure equalizes because of the flywheel inertia.  The flywheel energy turns the air motor into an air compressor which voids the first tank and pressures the 2nd.  This action continues until the inertial energy of the flywheel can no longer overcome the pressure differential.  The air flow/current now reverses and the process is repeated over and over until the frictional losses of the system bleed out the energy.    An antennae attached to the system would take on the form of a balloon teed into the circuit which is alternately inflated and deflated as the circuit resonates.