Rosemary Ainslie circuit demonstration on Saturday March 12th 2011

[cHeeseburger]

Yes, through the switching of the function generator
additional energy can be flown into the circuit via the
Gate Source and Gate Drain capacitances.

So it will be wise to just use a negative DC power
supply on the Gates to start and keep the oscillations.

Yes, this will eliminate the giant spikes but still a Kelvin sensing ultra-low inductance shunt should be placed on the battery side of the common ground point to eliminate the currents in the gate-source circuit loop resulting from the oscillations at 1.5MHz (as well as any gate drive spikes, which will go away if the circuit can be made to oscillate with just a DC bias).

Stefan, you must remember that it is not only energy that comes from the sig-gen flowing in the gate-source current loop (and showing up in the shunt even though it is not flowing in the larger circuit loop that includes the batteries). 

Ok.  This is more comforting.  We put a .5 Ohm resistor at the gate to measure the energy.  We established that there was something in excess of 5 watts - but that this was being returned to the functions generator.  One of the guys there said that there was enough capacitance associated with the generator to absorb this energy.  I am not qualified to comment.

Regards.
Rosemary

So Rosemary's team acknowledges that 5W of 1.5MHz RF is circulating in the gate circuit when there is no dynamic transition signal coming from the signal generator.

We see this clearly when the 1,5MHz oscillations are going and there is AC voltage at the gate having to exist across the 14nF of gate capacitance.  That represents significant power that is neither coming from the sig-gen nor flowing through the larger outer circuit loop and battery.  But it appears on the shunt because the shunt is inside both the smaller and larger current loops at present.  This why the shunt should be moved to the battery side of ground and thus taken out of the gate-source current loop.  If the goal is to measure just the battery current flow by itself, this must be done.

If this is done, please note that the polarity reverses on the shunt.  Think about that carefully and you will see that when current flows in the normal direction out of the battery (draining the battery) a shunt on the left (battery) side of the ground point will show a negative voltage below ground while a shunt on the right side (MOSFET source) of the common ground will show a positive voltage above ground.  Remember the two shunts are in series with ground at the center tap.

Regarding that non-driven approach (DC bias without input pulses) Rosemary might find it won't readily begin oscillating.  In my simulation, I used a DC bias and got continuous oscillation but I needed to have one single sharp pulse to get it to start going.  I'm not predicting one way or the other, just noting a minor point that I found using the simulator.  The actual hardware may be different.

Bryan

[Goat]

Dear Rosemary

Please forgive the intrusion in your thread, there seems to be a lot of issues about the measurements in your experiment.

A simple question if you will. 

Have you ever ran your circuit for a longer period of time than would be possible on a battery (or bank of batteries) than without your circuit to the heat resistive element?

Seems like your circuit and your goal as intended to generate heat without depleting the source battery (or bank of batteries) to pre-heat water or other uses could run this circuit once started and tuned indefinitely. If you don't mind me asking, how long have you ran this circuit without interruption?  I know you mentioned pushing the circuit and that the battery was still charged, but can you keep it running endlessly if not pushing it too much and still go past the C20 capacity rating for the battery?

Sorry for all the questions, I know you're busy but if you could answer the above I don't see what all the fuss about measuring is if you can keep the battery powering extra heat indefinitely  

Regards,
Paul

[Rosemary Ainslie]

Have you ever ran your circuit for a longer period of time than would be possible on a battery (or bank of batteries) than without your circuit to the heat resistive element?

Seems like your circuit and your goal as intended to generate heat without depleting the source battery (or bank of batteries) to pre-heat water or other uses could run this circuit once started and tuned indefinitely. If you don't mind me asking, how long have you ran this circuit without interruption?  I know you mentioned pushing the circuit and that the battery was still charged, but can you keep it running endlessly if not pushing it too much and still go past the C20 capacity rating for the battery?

Sorry for all the questions, I know you're busy but if you could answer the above I don't see what all the fuss about measuring is if you can keep the battery powering extra heat indefinitely  

Regards,
Paul

It's a good question Paul - and I've sort of answered it all over the place.  It seems to be a preferred way of proving things because it's so logical.  I have NOT managed to find any loss on our own batteries - used pretty well continuously for 5 or so months.  But the batteries are HUGE.  I'll try and find the post that refers to this and then repost it.  If you're asking this still then there are others with the same question. 

Hang ten - I'll post it hereunder - when I find it?  Not the quickest around this internet thing.  LOL

Kindest regards,
Rosemary

[Goat]

It's a good question Paul - and I've sort of answered it all over the place.  It seems to be a preferred way of proving things because it's so logical.  I have NOT managed to find any loss on our own batteries - used pretty well continuously for 5 or so months.  But the batteries are HUGE.  I'll try and find the post that refers to this and then repost it.  If you're asking this still then there are others with the same question. 

Hang ten - I'll post it hereunder - when I find it?  Not the quickest around this internet thing.  LOL

Kindest regards,
Rosemary

Thank you for your quick reply Rosemary, I am humbled at your statement "If you're asking this still then there are others with the same question." because it seems like your thread and purpose here has become mired in measurement issues. 

When you mentioned above "I have NOT managed to find any loss on our own batteries - used pretty well continuously for 5 or so months.  But the batteries are HUGE."  How HUGE was the battery as opposed to the resistive element and did the extended use show more heat than the battery bank could supply? 

If so, mission accomplished

Regards,
Paul

[happyfunball]

It's a good question Paul - and I've sort of answered it all over the place.  It seems to be a preferred way of proving things because it's so logical.  I have NOT managed to find any loss on our own batteries - used pretty well continuously for 5 or so months.  But the batteries are HUGE.  I'll try and find the post that refers to this and then repost it.  If you're asking this still then there are others with the same question. 

Hang ten - I'll post it hereunder - when I find it?  Not the quickest around this internet thing.  LOL

Kindest regards,
Rosemary

It's a simple question, what is the longest time you've run the circuit off the batteries? Why don't you know this offhand? Seems fairly important. May I suggest trying tinselkoala's requests on the bottom of page 1 as a starting point to answering questions which seem to be going around in circles.

Thanks.