Has anyone seen Lasersabers new motor runs on 1000uf cap

[gyulasun]

Hi Conrad,

Very nice job!

I think your scope was set to a vertical scale of 1 V/DIV for both channels and time scale is 20msec/DIV, right?
It looks like the JFET works as an oscillator whenever the induced trigger voltage is just good for the JFET to work as an amplifier (both the drain and the gate have inductive reactance from the coils). You can test how the real gate-source voltage changes i.e what AC voltage the 5 series coils provide if you disconnect the drive coil wire from the drain and push the rotor by hand to the approximate RPM it runs with when the 0,5V supply voltage was connected, under this condition the JFET cannot oscillate.

(You surely know that the 2SK170 conducts with its I_DSS drain-source current (so it has the maximum transconductance) whenever the voltage between its gate-source is zero. And this kind of JFET cannot conduct when the gate-source voltage is higher i.e. more negative than the -0.2V to -1.5V cut-off voltage as per the data sheet with the GR, BL or V designations shows.  So I mean this kind of JFET is not ideal for switching unless you use an outside negative bias between the gate and source to cut off drain current whenever there is no induced trigger AC voltage to control the gate-source.)

The ALD110800 or ALD110900 is a bit better in this respect because at zero gate-source voltage the drain-source resistance is 104 kOhm, quasi an open circuit for the 80 Ohm drive coil so a negligible current can flow in the coil. And when the trigger voltage will be more positive at the gate wrt the source, it can switch ON,  from data sheet the drain current is about 3mA when the V_GS=+4V (at V_DS=5V). With the V_GS=+4V the drain-source ON resistance is 500 Ohm.  (So your 80 Ohm drive coil and this 500 Ohm will behave as a voltage divider: smaller part of the supply voltage feeds the coil and the bigger part of it is dissipated across the FET.)
Notice: this type can have a maximum of 10V between its drain-source, higher than this may cause damage, so be careful with the inductive spikes.

Gyula

[TinselKoala]

@Conrad: very nice work!
Makes me long for my precision tooling, which is still out of reach.

Also... what Gyula said, ditto.

[SkyWatcher123]

Hi folks, here is some information about one of Joseph Newman's motors.
It seems to have some similarities, like the long series coil and possible energy return.
COIL PARAMETERS:
                Weight ...........................  9,000 pounds
                Copper Wire Length ...............  55 miles
                Coil Inductance ..................  1,100 Henries
                Coil Resistance ..................  770 Ohms
                Coil Inside Diameter .............  4 feet
                Coil Height ......................  4 feet
ROTOR PARAMETERS:
                Rotor Weight .....................  700 lbs. ceramic magnets
                Rotor Length .....................  4 feet
                Moment of Inertia ................  40 Kg-sq.m.
                Magnetic Moment ..................  100 Tesla-cu.in
BATTERY PARAMETERS:
                Battery Type .....................  6 Volt Ray-O-Vac Lantern
                Total Series Voltage .............  590 Volts
DYNAMIC PARAMETERS:
                Torque Constant ..................  15,400 oz. in./amp
                Drag Coefficient .................  0.005 Watts/sq.rpm.
                Q at 200 rpm .....................  30
                Power Factor, 200 rpm ............  0.03
The torque constant was measured at DC and agrees with  calculations.  The drag
coefficient  was  measured  by  plotting  the  motor  speed  versus  time after
disconnecting the batteries.   It was found  that the decay is exponential with
the  drag  torque  being  proportional to  the angular speed.   With  the motor
operating at 200 rpm, the following measurements and calculations were obtained:
RESULTS:  200 RPM at 590 VOLTS
                Battery Input Current ............  10 milliampere
                Battery Input Power ..............  6 Watts
                Rotor Frictional Losses ..........  200 Watts
                RF Current (rms) .................  500 milliampere
                RF Ohmic Losses in Coil ..........  190 Watts
                Additional Loads .................  Fluorescent Tubes
                                                    Incandescent Bulbs
                                                    Fan (belt driven)
The frictional  losses  are  computed  from  the measured drag coefficient. The
ohmic  losses are  computed from the coil resistance.   Without considering the
additional loads, it is seen that the output energy of the machine exceeded the
input by a factor of 65!

peace love light
tyson

[SkyWatcher123]

Forgot to include this important piece of information.

The most  important design rule specified by the
inventor is that the length of wire in the motor coil be very long; preferably
long enough so that the switching  time between  current  reversals is shorter
than the  time required  for propagation of the current  wavefront through the
coil.   Various  models  contain  up to 55 miles  of wire, with  air core coil
inductances of up to 20,000 Henries.  The permanent magnet armatures have very
large magnetic moments.  Thus the motors exhibit  high torque with low current
inputs.  The motors generate large back current spikes consisting of pulsed rf
in the 10-20 MHz  frequency  range.   These spikes  provide  large  mechanical
impulses to the rotor, energize fluorescent tubes placed across the motor, and
tend  to  charge  the  dry cell battery pack.  The total generated energy ----
consisting of mechanical work,  mechanical friction,  ohmic heating, and light
---- is many times larger than the battery input energy.

peace love light
tyson

[Magluvin]

New vid  New cap, seems to accelerate!

http://www.youtube.com/watch?v=dCf-4zFmjNk

Mags