Has anyone seen Lasersabers new motor runs on 1000uf cap

[conradelektro]

Made some measurments to my toy; it's oscilating from 0.9 to 1.1 mA at full rpm. Also made another rotor more balanced and with no holes to reduce the air drag

@mariuscivic: now, with your nice contraption which uses very little power, you can try to recapture electric energy with pancake coils or any other strange coils (wich as some people claim cause no LENZ losses).

@gyulasun: thank you for the explanation of current flow through a base to base connection from PNP to NPN transistor. Still, it is astonishing that I needed 12 Volt to make it work? I tried 300 Ohm and even no resistor at all. Power draw increased but still, it would only work with 12 V or more.

I did some more tests with "disconnecting a coil at both ends":

The circuit with the two IRLIZ44 MOSFETs worked very well. But I could not see any charging of the cap by the diodes.

I set the power supply to 6 Volt, waited till the rotor settled at a constant speed and then switched off the power supply. With my Russian mechanical stop watch I timed how long it took the 1000 µF cap to discharge from 6V to 2V (while the motor slowed down). It always took about 23 seconds, with diodes or without diodes. The same test while the cap discharged from 3V to 1.5V in about 32 seconds, and also no difference.

The circuit works of course even better with only one IRLIZ44. The rotor turns faster with less power and a feedback diode (or LED) increases power draw by about 10% and slows the rotor down.

So much for recharging a cap with the back EMF of a coil! Now, do you believe it will work any better with two Reed switches (in place of the two transistors)? Each coil in my little motor has 90 Ohm DC resistance, in sum the six coils have about 540 Ohm DC resistance.

Greetings, Conrad

P.S.: I bought the Russian stop watch at a fair in Vienna for 20.-- EUR where they sold old mechanical photo cameras (a few years ago). It must be 50 years old or even pre second world war, and is very heavy. It allows to take two times (one digit stops, the other continues). All mechanical, no electronics.

[gyulasun]

Hi Conrad,

I think the setup would work better with reed switches replacing the two transistors. At least you could get rid of the saturation voltage drops between the collector-emitter of the bipolar transistors and reeds may still have less DC resistance than your MOSFETs at lower gate-source voltages (when your supply voltage is 1-2V only). However, I do not expect a significant improvement.

I have not found an explanation why your bipolar transistor version needs a minimum of 12V supply or higher to operate, sounds strange for sure. Perhaps you may have some other pnp and npn transistor types to test this behaviour? 
It all sounds like one transistor stage (either the pnp or the npn) would limit the maximum current takeable by the other stage and vice versa, here I assume if you omit any one stage and operate the setup with a single transistor, then the single bipolar transistor stage would surely operate from 1-2 Volt supply again as is normal.  But why this limiting behaviour has a voltage window of 12V I do not know yet.
Another notice: the lack of recharging the capacitor even a little may show that too much part of the recovered energy from the collapse is wasted in the coils' resistance (540 Ohm).  Because the source of the spikes are the coils so the generator inner impedance is a drawback from energy recovery point of view.

Greetings, Gyula

[conradelektro]

@gyulasun: thank you for the reply.

I will try two Reed switches instead of the two transistors. But first I will try to charge a separate cap. My guess is that it will charge to less than the supply Voltage, which would explain why a supply cap never gets charged. Supply cap charging can only be achieved if power is supplied to the rotor (e.g. by blowing air over it) so that it turns faster as it would with the momentary cap Voltage.

One could overcome the lesser Voltage of the BEMF spike by introducing an up-transformer (as Wattsup is suggesting http://www.overunity.com/13523/has-anyone-seen-lasersabers-new-motor-runs-on-1000uf-cap/msg363047/#msg363047), which I will try as well. My suspicion: whatever one does it has to be paid for with supply power.

My other suspicion: the Ossi motor would have performed equally well without the return diodes. Did anyone try that? Lasersaber's 3D-printed motors are in principle Ossi-motors (but with a different and simpler drive circuit). The original Ossi motor used 4 very high impedance coils (for Audio speaker adaptation) which had very high DC resistance. Lasersaber's motors would run on a 1.5 Volt AAA rechargeable battery for many days as did the Ossi motors.

P.S.: I have little luck with the DadHav circuit. It did not work with MOSFETs and not with BC547 / BC549. I could not make it work with any of my pulse motors. By chance I have the same transistors as Lidmotor uses (2N3906 and 2N4401) http://www.youtube.com/watch?v=auNqKNZLbc0 (see at minute 5:26) and I will try them. Like a base to base connection it only seems to work well with specific transistors. Eventually I will order exactly the same transistors as DadHav uses (MPS-A06 / MPS-A56, I do not have the MPS-A56). I like that DadHav's circuit does not need any "trigger" like trigger coil, Reed switch or Hall sensor. The drive coil (or series of coils) is at the same time driver and trigger.

Greetings, Conrad

[ALVARO_CS]

hi
I read long time ago a PDF supposedly from Ossie himself in which he recommended as the best position, to put the reed switch INSIDE the coil. (that is at center).
cheers

[conradelektro]

hi
I read long time ago a PDF supposedly from Ossie himself in which he recommended as the best position, to put the reed switch INSIDE the coil. (that is at center).
cheers

Have to try that. It is difficult with the coils of my present little six coil motor, but in my next design (which is under way) I will leave the hole through the coils open on both sides (through which I can insert a Reed switch). Good idea.

My guess: with the Reed switch inside the coil it's ON-time is very short, which reduces power draw. It is also a good position to trigger the pulse, just as the magnet is dead centre over the coil. The momentum of the rotor assures that it is pushed in the right direction. And the motor would run in both directions equally well (after an initial push).

With my little 6 coil motor I see that the pulse happens as the magnets are almost past the coils. This is good for self starting in the right direction but not optimal.

The power of collaboration, many good ideas are pooled.

Greetings, Conrad