Has anyone seen Lasersabers new motor runs on 1000uf cap

[lumen]

I thought the diode on the cap was funny also! If it was connected in one direction, it could only serve to charge the cap and nothing could flow out to power the motor.

If it was connected in the other direction, then it could not charge the cap but the energy in the cap could flow out to run the motor.

Something isn't making sense with that diode unless it's just burnt out and conducts in both directions.

[conradelektro]

@Farmhand: I was just thinking, how can one adjust the ON-time with Reed switch? To everybody, any ideas? Iron shield (slit)?

@Wattsup: I will try the Reed switch in the middle of the coils as you suggested.

I tried a diode at the capacitor (both directions, both sides of the capacitor). But it did nothing once the battery or power supply was disconnected.
I tried with this schematics http://www.overunity.com/13523/has-anyone-seen-lasersabers-new-motor-runs-on-1000uf-cap/msg361768/#msg361768

Will be back on Monday.

Greetings, Conrad

[gyulasun]

Hi Conrad,

The ON time of a reed switch could be influenced:

By tinkering with the distance and angle from the rotating magnets (if rotor magnets are too strong, their flux may influence reeds at distance of 4-6 cm, rendering the positioning very critical

By using two reeds in series, the reeds being at certain distance from each other

By using a separate small rotor disk fixed on the same shaft, with small magnets on it, just for controlling the reed,  this disk is being independent from the main rotor magnets. 

You mention iron shield: it sounds good to me, although it may cause some drag to the rotor magnets, depending on its size and permeability.

Gyula

[TinselKoala]

I thought I had already posted the fact that a reed switch can be "tuned" by using a small fixed magnet on the opposite side of the switch from the moving triggering magnets. You can get almost complete control over the duty cycle of a reed switch by carefully choosing and moving this bias magnet until you get the reed performance you need. Also, putting a small ceramic cap directly across the reed as close as possible to the switch will help to preserve your switch contacts and doesn't cost anything (much) energetically.

The cap in Lasersaber's video is marked 10K 100. A poly film cap of that size cannot possibly be 10 microFarads. Looking on the internet for capacitor marking codes, I find that the "K" means thousands of picofarads. So 10K means 10 thousand picofarads, or 10 nanoFarads, or 0.01 microFarads.
http://www.electronic-circuits-diagrams.com/tutorials/capacitors.shtml

The energy stored in a 0.01 uF cap at 100 volts is (0.00000001)x(100)x(100)/2 Joules == not very much, 0.00005 Joules. From previous experience with jewelled pivot bearings and magnet rotors, I'll estimate that the power dissipation of that little rotor at the speeds we are seeing is on the order of only a couple of milliWatts. Maybe even less, hundreds of microWatts perhaps. Or even less.... since the cap seems to be able to accelerate the rotor from slow, and keep it running for tens of seconds.
It would be nice to see some instrumental data. The rotor could be spun up to a known RPM then allowed to run down, unpowered, and carefully timed. The average of a dozen such runs to the same RPM would be a number that could be relied upon. The rotational Moment of Inertia of the rotor can be easily calculated if the weights of the components are known. This value along with the RPM will give the energy stored in rotation, and the average rundown time will then give an average power dissipation value over that RPM range. Then the testing with the cap could commence. Use the air blast to run the rotor to a known RPM again with the cap switched out of the circuit. Then switch in the cap and time the rundown time. The difference in the powered vs unpowered rundowns will allow you to see how efficient the capacitor really is, whether the system is putting any energy back into the cap while it's running down, and will allow you to determine whether or not any further mods help or hurt.

[TinselKoala]

@Mags:
Disconnect the capacitor and diode from the coils, and spin the rotor while monitoring the coil output on the scope. The rotor magnets passing the coils makes AC, right?

How are you going to charge up a capacitor with AC, unless you also have a rectifier in series with the cap?

Further.... if the diode conducts in both directions.... it's not a diode. A 1n60 germanium would probably handle the strain OK and act as a rectifier with low forward voltage. A Schottky diode might work even better.