FUELLESS CAR PROTOTYPE by ISMAEL MOTOR

[forest]

Thanks Konehead

What is J2 and J3 on schematic ? Doesn't transformer shift phase of original sinewave current ?

[konehead]

Hi forest

J2 and J3 are the Junction "out"s I guess is what the J stands for...there are two of them in case you choose to skip the chopping feature that you can do with the pot 3
These hook up to the gates of the mosfet banks, its the signal that finally triggers the mosfet banks.
you need to have a trnasformer with AC signal that matches up with what you want to short - lets say you want to short the run-cap phase of a rotovertor AC motor - so good idea for that is put the HV side of a MOT (Microwave Oven Transformer) across the run cap phase, and use the LV side of the MOT to control/signal this circuit.
If you have some sort of generator working that you want to short the phases of the coils at peaks, then put across a coil or phase, some sort of small transformer, or even a small aircore coil, to create the AC siden wave that triggers this circuit...just check with scope that the "signal" wave form look similar to what you are actually going to be shorting.

[forest]

Konehead

You said
"Also for coil-shorting you should have BIDIRECTIONAL mosfets - that is, two mosfets connected at gate and source leads (or two banks of paralelled mosfets) so the mosfets will switch AC...the switching now occurs between the "leftover DRAIN" leads of the mosfets.
"


I can't imagine that. Why source leads should be connected too ?  Could you draw schematic of this bidirectional mosfets ?

[konehead]

Hi Forest

Here is schematic showing two mosfets hooked up bidirectionally, also it is a coil-shorting circuit too. Note the 10K pull-down resistors too...which make it so the driver chip will the sacrifical component, not the mosfets, if some wires get crossed or something.
This circuit has its timing of when the mosfets turn ON-OFF controlled by hall effects, which would work with a generator-rotor spinning around  wtih some small trigger-magnets on rim of  rotor, in order to trip the hall effects....so to find peak period, all you have to do is adjust the position of the hall effects in relation to the spinnign trigger magnets... you can  mount the halls on a adjsutable swivel- plate that can be locked in place once you find the timign you want...
the small coil off to the left is jsut a way to replace the 9V battery, that supplies the small DC power for the switching (driver, halls and mosfets)  via being induced by the rotor-magnets, once the generator rotor gets going around....

[forest]

Thank you, really interesting schematic. How did you resolved the danger of dielectric breakdown of capacitor due to too high voltage spikes from coil ? do you have any snubber or just measured max voltage from shorted coil and had chosen proper capacitor ?