On Fri, Oct 22, 2010 at 12:26 PM, Sebastien Lelong < [email protected]> wrote:
> > > 2010/10/22 vasile surducan <[email protected]> > >> >> >> On Fri, Oct 22, 2010 at 11:43 AM, vasile surducan <[email protected]>wrote: >> >>> >>> >>> On Fri, Oct 22, 2010 at 10:56 AM, vasile surducan >>> <[email protected]>wrote: >>> >>>> >>>> >>>> On Fri, Oct 22, 2010 at 10:06 AM, Sebastien Lelong < >>>> [email protected]> wrote: >>>> >>>>> Hi Vasile, >>>>> >>>>> 2010/10/22 vasile surducan <[email protected]> >>>>> >>>>> Hi Seb, >>>>>> >>>>>> Looks to me that you have understand well that different DC motors >>>>>> will give you different EMF values: >>>>>> >>>>>> http://sirloon.net/loonaweb/sirblog/experimenting-back-emf-motion-feedback >>>>>> <http://sirloon.net/loonaweb/sirblog/experimenting-back-emf-motion-feedback>So, >>>>>> that's it, a poor method using an analog feedback, if you want universal >>>>>> solutions seems to me you have to switch on digital feedback, which as >>>>>> far I >>>>>> know can't be EMF. >>>>>> >>>>> >>>>> Do you mean something like encoded wheels ? bemf is really nice to have >>>>> because it's not invasive, you can control any DC motors without modifying >>>>> the structure (which is great when hacking RC toys) >>>>> >>>>> >>>>>> You can't do it without modifying dividers. >>>>>> >>>>> >>>>> Is electronic that limited ?? C'mon, there should be a trick ! >>>>> >>>> >>>> Variable gain amplifier. It modifying dividers in software keeping the >>>> ADC resolution constant. Still a s**t... >>>> :) >>>> >>>> >>> There is another way: when read EMF the motor acts as a generator. >>> Loading it with a variable resistive load (switched digitally using some >>> transistors) will decrease the EMF level as you wish. However that will >>> brake the motor as well, as high as the load becomes lower. Probably with 2 >>> loads you can use two different DC motors. >>> Do you intend to manufacture some kits? >>> >> >> >> Ok, thats the best ideea: an active load (programmable constant current >> source) >> > > Any readings about this (for humans) ? > Send me the schematic (or link) of your H bridge or whatever you have for supplying the motor. > > >> driven by the 16 level internal reference voltage, switched on the motor >> coil only when back EMF is read. >> > > 16 levels internal reference voltage ? What do you mean ? > http://ww1.microchip.com/downloads/en/devicedoc/40044f.pdf <http://ww1.microchip.com/downloads/en/devicedoc/40044f.pdf>take a look at page 67, you have in fact 32 different voltage levels (VR0 to VR3 plus VRR). Use this voltage from RA2 and drive a programmable current constant source connected in short circuit on the motor. > > > Thanks, > Seb > > -- > You received this message because you are subscribed to the Google Groups > "jallib" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<jallib%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/jallib?hl=en. > -- You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/jallib?hl=en.
