Muller Dynamo

[mondrasek]

Between yard work and family life I was able to record this data.  Unfortunately it does not tell me much.  But I offer it to everyone so they will understand what today's testing results are. 

Even "bad" results are "results" that should be shared.

Also, someone other than I may see something in this data that I don't recognize.

This data was taken with the load resistance constant at ~95 Ohms.  Then the RPM was swept from maxmum to minimum (where the drive motor M56732AL IC drops out) by decreasing the drive motor input V.

Unlike the previous tests, the input power data presented here is not from the input to the entire motor drive circuit.  These are the readings of the input power from the drive circuit to the BLDC drive motor.  This is because at lower input V levels much power is dissipated by the motor drive circuit regulator as heat (the heat sink gets to 50C+ easily).  So these readings are what the drive motor needs to achieve the recorded RPM and therefore o/p power without consideration for the power lost in the circuitry.

M.

[xenomorphlabs]

Just got home from work, going to play with my motor in the garage. Last night I was playing around with it and I am having issues with the 2 ohm drive coil pair, they want to much current. But on the flip side I have gained rpm from 2300 (old coils)to over 5000 rpm. I must admit that I get scared running it that fast with no protection from flung magnets.... But the bigger problem is that it is really heating up the transistor. My circuit is similar to what Romero used and his coils were low ohms (2?). Any ideas how to cool this puppy down without a micro controller? Also has it been determined that the bucking coils is the way to go? I have lots of testing to do, but first I must have a stable drive circuit, so that is what I will be working on first.
Peace
rawbush

Why don't you just slam in a resistor in the base of the transistor?
Start with like 500 Ohm or so, this should bring down the current.

[mondrasek]

Also has it been determined that the bucking coils is the way to go?

Please note that everything below is under the ASSUMPTION that you are asking about gen coils.  If you are asking about pulse motor drive coils then it does not apply and please just ignore this post.

My opinion is that if you have your coils in series adding, you have a conventional generator.  Once you switch to series bucking, well then:  Now you may have a ZPEC if tuned to the correct frequency (RPM to rotor mag spacing to rotor mag location wrt distance from rotational axis).

The stuff in the () is then the challenge.

Oh!  Don't forget the Coil to Rotor Mag gap spacing!  Or the number of turns on the coils.  Or the permeability of your cores.

And then there is the backing magnets.  Those are cool.  But you will have to figure out how they relate to the rest of those other variables.  What I have seen (preliminarily) showed that they can increase Vout (if your coils are matched pretty darn close on top and bottom) to a point (too close starts to decrease the V increase).  BUT, I also noticed an RPM decrease (power out decrease) from the rotor when I used the backing mags. 

I have not tested if the power loss (RPM decrease) due to the introduction of the backing mags (Vout increase) is a net gain or loss or neutral tradeoff.

So many tests.  So little time.

Where is TK!?!?!

M.

[Rawbush]

Why don't you just slam in a resistor in the base of the transistor?
Start with like 500 Ohm or so, this should bring down the current.

You mean in series from the hall to the base?

[xenomorphlabs]

You mean in series from the hall to the base?

Yes, that's how you bring the transistor current down or you put a 10 Ohm Power Resistor in series with your drive coils.