Re: A novel pulsed motor circuit.

[hoptoad]

@hoptoad & TinselKoala
thank you for your help.
An additional Question; do you think that opto switches would be better for control of pulsed motors?
I have salvaged a couple of these, from a discarded (junk) printer.
I can get from my nearest photocopy-shop a couple of cut opaque self adhesive vinyl discs, and superposing both disks one would be able to control the duty cycle.
Even it should be possible to make two or three gaps for the same pulse.
what do you think ?
cheers
Alvaro

In my early adams experiments in the 1990's I made up a flat circular PVC disk with 4 triangles cut into it at 90 deg apart. Basically a plastic version of Adam's original switch. It was mounted onto the rotor shaft separately from the rotor itself. I used a high intensity Led (to send) and a Photo Sensitive Transistor (to receive) to make my own (primitive) opto-control.  I did this because normal opto couplers have such a short physical gap to play with. Anyway, as primitive as it was, it worked a treat. The best thing was the control over the duty cycle. I could vary the duty cycle from zero to 50% easily, and I could also adjust the pulse firing angle easily.

Eventually in the mid 90's, I made a PVC cylinder with a thick solid cap on one end, with a hole drilled centrally in the cap, that slid tightly onto the rotor axle. It had triangles cut into the sides. This allowed me to control the duty cycle of multiple coil phases synchronously. I used a small neon on the inside of the cylinder as a common sender, and multiple PST's on the outside of the cylinder as receivers for each of the different phases. Both sender and receiver/s were mounted on a single adjustable bracket which could be pushed or pulled along the depth of the cylinder by turning a screw. It was another primitive switching system that proved to be very effective and easily adjustable.

Cheers

[ALVARO_CS]

Thanks for the hints, very stimulating.
I followed much of the info at the totallydamped pages (I even saved all in my PC, to study)
In my experiments, I found that using a driver coil similar to the Muller, 9 layers x 21 turns, plus 9 layers x 7 turns with 0,4mm wire bifilar, and core ferrite rod 8mmD. It works better if I add at the back side a ferrite rod from a radio receiver. 8mm D x8 cm length.The motor speeds up a lot, not increasing the input power.
I put a coil in that rod 0,3mmD wire x some 2600 turns but it gives not enough beef to sustain rotation looping it to the motor. Anyway I guess that we are all looking for a self-sustaining device. and may be the success of one of us will be the success of everyone.
Cheers
(as you may guess, english is not my mother language)

[TinselKoala]

@Alvaro....
First, don't worry about your English !! Believe me, it's better than that of many native English speakers posting here, as you can probably tell already. 

Then... as far as switching/commutating goes... I've tried just about everything. Optical, Hall Effect, reed switches, self-inductive triggering, even mechanical commutators. I have found that for my purposes Hall effect switches are the most flexible and easy to use. The best optical systems that I have used are from a company called USDigital; they make shaft encoders and detector modules. Their little detector modules can be used stand-alone with your own chopper wheel, and used with their 4000-line wheels give incredible position resolution.
You can also make your own system using chopper wheels and a CdS photoresistor sensor. I just found one I made years ago out of a floppy disk with a hole cut into the edge.
By overlapping two wheels with matching cutouts, you can make an easily-adjustable timing and dwell (duty cycle) system, by changing the amount of overlap of the cutouts.
Reed switches have their charms too, but they are relatively expensive for good ones and they do weld shut easily with high currents and inductive loads. They can be adjusted in-place by moving or by positioning tiny biasing magnets where needed.
Mechanical commutation, like a small DC motor has, can be interesting if you need extremely noisy and jittery switching.

ETA: The "ideal system" for many purposes would be, IMHO, a USDigital sensor with their 1000-line wheel, feeding into an Arduino or similar microcontroller, which then switches a mosfet output stage (or a mechanical relay if you like). The 1000-line wheel will give 4000 line effective resolution per rotation, the Arduino counts the lines and turns on an output when so many lines come by, then turns it off again after so many more lines go by. Very precise and fast, but not the cheapest solution. However it does allow odd, varying duty cycles and timing to be achieved. You can even vary both "on the fly" by using a potentiometer or two inputs to the Arduino to tell it "how many lines" to count before switching the output mosfet.

[ALVARO_CS]

@TinselKoala
thank you. I take note.
As my knowledge in electronics is quite short, I tend to replicate, and/or modify simple circuits as far as I can understand and therefore control the processes I am workig with.
cheers