Muller Dynamo

[mondrasek]

.01uF cap between +Vin and Vground to the BLDC motor drive circuit does not reduce the "antenna" effect of a change in RPM when either DMM lead is touched to the circuit.  I'll try the .001uF I have.

After that I will try those same caps on the motor drive circuit CTL signal (resistance current limited V of ~2V off of a separate 5V regulator).  This is the only other physical connection to the motor drive circuit.  But it must use the same ground as Vin, so maybe this is the "problem?"

M.

[mondrasek]

So the .001uF did not help between Vin and Vground to the motor drive circuit anymore than the .1uF or .01uF did.  So I tried those same values between Vground and Vctl to the BLDC driver circuit.

.1uF killed the motor the fastest.
.01uF killed it too, albeit over a longer time span.
.001uF slowed it down dramatically, but the motor still ran.

Please note that the .1 and .01uF caps are Metal Polyester Film, and the .001uF is a Ceramic Disk type cap.

If anyone would like to explain the characteristic differences between these different types of caps I would appreciated it.  It would save me some "Googleing" time.

M

[maw2432]

Thanks for the result you shared  that saves me time  to  verify the performance
cheers
totoalas

Totoalas,  the only problem is when you take the coil out of the plastic base of the kinetic art toy, you need to break the plastic and it is not very usable again for a kinetic art toy.   The coil does have a lot turns of very thin wire. Well over 8000.   It works both directions of the rotor turning.     
The one I use to show my Science class students has been working for over 5 years now.   
No need for an on off switch.   Only uses current when current is generated in the pickup part of the coil.   No need for hall sensors or other switching circuits etc.    However,  I do think it has its limits for switching speed.   So I suspect you would not come even close to double rpms just by adding a second coil.    Need to really test though. 
It really is a fun coil to play with.   
Bill

[mondrasek]

If this does not work , connect to an earth connection instead of negative rail and repeat tests.

What Earth connection are you suggesting?  Should I connect it to the Earth ground of my mains?

M.

[neptune]

@Mondrasek . Hi Mo. Well done remembering Hyde Park . From a functional point of view there is not a lot of difference between ceramic disc caps and polyester . They are both suitable for what we are trying to do . Here is another quick and dirty idea . For this , you need a "choke" or coil . For a rough test a spare Muller generator coil would do . Try connecting it between your antenna and the point where your antenna connects to the circuit . If this works , try connecting it between the end of your multimeter test lead and the test point you would normally put your multimeter test lead onto . This will effect any voltage reading you take , but only by a tiny fraction .Try the choke with and without its ferrite core . Remember that in the fight against RF interference , there are only two basic tools , the cap and the choke . The trick is always figuring out where to connect them . We have to be careful with chokes , which pass DC and block AC [ of the right frequency depending on the inductance of the coil] because chokes can cause DC short circuits and" allow the magic smoke to escape" from components .
Only connect to mains earth if you are 100% certain of what you are doing . Alternatives are a metal water pipe that you know goes into the ground , or an earth spike in the garden .