"Rodo" <dsp1024@yahoo.com> wrote in message news:<WtALc.13795$Iz3.9732@nwrddc01.gnilink.net>...> Hi all... > > I need to make a circuit that needs to spin on the shaft of a small dc > brushless motor. I thought I could use a permanent magnet mounted on the > base of the shaft of the motor (not moving) and some coils that will be > spinning on the pcb. I don't know if this will work or provide enough power > (need 5mA) to the spinning pcb . Any better ways ? > > BTW I can't seem to find a dc brushless motor manufacturer. Can you suggest > any ? > > ThanksHave a high intensity LED, fixed to the chassis, shine on a "solar cell" fixed to the rotating circuit board. A small-light-powered-calculator I pulled apart used an LED as a shunt regulator so evidently they can deliver mA no probs. Robin
How to provide power to a spinning circuit ?
Started by ●July 21, 2004
Reply by ●July 22, 20042004-07-22
Reply by ●July 22, 20042004-07-22
"Rodo" <dsp1024@yahoo.com> wrote in message news:<WtALc.13795$Iz3.9732@nwrddc01.gnilink.net>...> I need to make a circuit that needs to spin on the shaft of a small dc > brushless motor. I thought I could use a permanent magnet mounted on the > base of the shaft of the motor (not moving) and some coils that will be > spinning on the pcb. I don't know if this will work or provide enough power > (need 5mA) to the spinning pcb . Any better ways ?A really tiny windmill, perhaps? http://adsabs.harvard.edu/cgi-bin/nph-bib_query?2000SPIE.3888..256K This could be a cutting edge project.
Reply by ●July 22, 20042004-07-22
Jim Stewart wrote:> Rodo wrote: >> Hi all... >> >> I need to make a circuit that needs to spin on the shaft of a small dc >> brushless motor. I thought I could use a permanent magnet mounted on the >> base of the shaft of the motor (not moving) and some coils that will be >> spinning on the pcb. I don't know if this will work or provide enough >> power (need 5mA) to the spinning pcb . Any better ways ? > > You left out too many details. > > 1. How fast? > 2. How many are you going to build? > 3. How much money do you have? > 4. How long does it have to last?He left out more than a few details (I have seen his responses to the above some of which were just a bit vague). 5. How much space do you have to play with 6. How much current does your PCB circuit require, what voltage. 7. Can the topology of the space be described, or better still, drawn and placed on a website somewhere. 8. What sort of environment is this for 10. Is power the only contactless transfer you require 11. How big is the circuit on the PCB and can a slightly larger board be accommodated. The OP also indicated that he was looking for the supplier of brushless DC motors. PML Flightlink would be one outfit that he could try. http://www.pmlflightlink.com/ -- ******************************************************************** Paul E. Bennett ....................<email://peb@a...> Forth based HIDECS Consultancy .....<http://www.amleth.demon.co.uk/> Mob: +44 (0)7811-639972 .........NOW AVAILABLE:- HIDECS COURSE...... Tel: +44 (0)1235-811095 .... see http://www.feabhas.com for details. Going Forth Safely ..... EBA. www.electric-boat-association.org.uk.. ********************************************************************
Reply by ●July 22, 20042004-07-22
"Rodo" <dsp1024@yahoo.com> wrote in message news:WtALc.13795$Iz3.9732@nwrddc01.gnilink.net...> Hi all... > > I need to make a circuit that needs to spin on the shaft of a small dc > brushless motor. I thought I could use a permanent magnet mounted on the > base of the shaft of the motor (not moving) and some coils that will be > spinning on the pcb. I don't know if this will work or provide enoughpower> (need 5mA) to the spinning pcb . Any better ways ?Take a look at this: http://bobblick.com/techref/projects/propclock/propclock.html
Reply by ●July 22, 20042004-07-22
Paul E. Bennett wrote:> Jim Stewart wrote: > > >>Rodo wrote: >> >>>Hi all... >>> >>>I need to make a circuit that needs to spin on the shaft of a small dc >>>brushless motor. I thought I could use a permanent magnet mounted on the >>>base of the shaft of the motor (not moving) and some coils that will be >>>spinning on the pcb. I don't know if this will work or provide enough >>>power (need 5mA) to the spinning pcb . Any better ways ? >> >>You left out too many details. >> >>1. How fast? >>2. How many are you going to build? >>3. How much money do you have? >>4. How long does it have to last? > > > He left out more than a few details (I have seen his responses to the above > some of which were just a bit vague).I enjoy helping people, but not when the questions are posed in a "smash-and-grab" style. If I'm going to give away my time and knowledge, I'd at least like my intellectual curiosity pleased out of the deal. I think most of the regulars here would agree.
Reply by ●July 22, 20042004-07-22
Hi Rodo, How about transmitting a little power on a license free band such as ISM (maybe 13.65MHz?), picking it up via small coils on the shaft and rectifying it there. Of course you'd have to check the legal situation in the countries where this is going to be marketed. Regards, Joerg http://www.analogconsultants.com
Reply by ●July 23, 20042004-07-23
Rodo wrote:> Hi all... > > I need to make a circuit that needs to spin on the shaft of a small dc > brushless motor. I thought I could use a permanent magnet mounted on the > base of the shaft of the motor (not moving) and some coils that will be > spinning on the pcb. I don't know if this will work or provide enough power > (need 5mA) to the spinning pcb . Any better ways ? > > BTW I can't seem to find a dc brushless motor manufacturer. Can you suggest > any ? > > ThanksTry a search for "Propeller clocks" they much power a spinning led bar
Reply by ●July 23, 20042004-07-23
Jim Stewart <jstewart@jkmicro.com> says...> >I enjoy helping people, but not when the >questions are posed in a "smash-and-grab" >style. If I'm going to give away my time >and knowledge, I'd at least like my intellectual >curiosity pleased out of the deal. > >I think most of the regulars here would >agree.There is a great web page on this very subject: How To Ask Questions The Smart Way http://www.catb.org/~esr/faqs/smart-questions.html -- Guy Macon, Electronics Engineer & Project Manager for hire. Remember Doc Brown from the _Back to the Future_ movies? Do you have an "impossible" engineering project that only someone like Doc Brown can solve? My resume is at http://www.guymacon.com/
Reply by ●July 23, 20042004-07-23
"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message news:LwVLc.194$0Y7.113@newssvr27.news.prodigy.com...> Hi Rodo, > > How about transmitting a little power on a license free band such as ISM > (maybe 13.65MHz?), picking it up via small coils on the shaft and > rectifying it there. > > Of course you'd have to check the legal situation in the countries where > this is going to be marketed. >We tried it - the shaft is prone to get most of the power and convert it to heat due to iron losses. The coupling link geometry has to be designed so that the magnetic field hits the secondary coil but not the shaft and surrounding metal parts. The solution in our case was a ferrite transformer at 20 kHz. The power transferred was small, some hundreds of mW. It showed that the transformer air-gap variation due to mechanical tolerances of shaft mounting had a pronounced effect on the transfer efficiency. Tauno Voipio tauno voipio (at) iki fi
Reply by ●July 23, 20042004-07-23
Guy Macon <http://www.guymacon.com> wrote:> > Jim Stewart <jstewart@jkmicro.com> says... >> >>I enjoy helping people, but not when the >>questions are posed in a "smash-and-grab" >>style. If I'm going to give away my time >>and knowledge, I'd at least like my intellectual >>curiosity pleased out of the deal. >> >>I think most of the regulars here would >>agree.We agree, but some posters do need a little help in framing their questions properly.> There is a great web page on this very subject: > > How To Ask Questions The Smart Way > http://www.catb.org/~esr/faqs/smart-questions.htmlAhhh!! you beat me to it Guy. Great page for advice but a bit long winded (could all have been said in much fewer paragraphs). -- ******************************************************************** Paul E. Bennett ....................<email://peb@a...> Forth based HIDECS Consultancy .....<http://www.amleth.demon.co.uk/> Mob: +44 (0)7811-639972 .........NOW AVAILABLE:- HIDECS COURSE...... Tel: +44 (0)1235-811095 .... see http://www.feabhas.com for details. Going Forth Safely ..... EBA. www.electric-boat-association.org.uk.. ********************************************************************
