On Sat, Oct 23, 2010 at 4:22 AM, Oliver Seitz <[email protected]> wrote:
> > > The constant current leads to a constant voltage at the > > external resistor. In fact you're subtracting a known > > voltage from the EMF voltage you want to measure. > > About like this: > http://johannes.eventify.de/kiste-temp/Voltage_shifter.jpg That's the same thing I described except the 100K in series with the motor (which is the V+ source in this case). Which is the output impedance on "to analog input" line? I think 100K... Replace the BC547 with a 500mA darlinghton, 0-2.5V with a variable reference voltage from PIC, and 10K resistor from the emiter with a smaller resistor, 100K with 0 ohm. Forget about the Hz to GND line since you're able to switch off the reference, but add 10K from Vref to ground to avoid false current generation if Vref becomes by accident an input. If the brake time is less than 50-100uS, probably that will not alter too much the speed, nor the movement since there is a movement conservation (inertia). When the motor is generator, any load will decrease the EMF voltage in the same way any mechanical load on a motor is increasing the current sourced (and decrease the power supply voltage if that hasn't enough power). BTW, I'm wandering why nobody filter than EMF noise. Seb, I think you have two software programmable solutions, choose one and experiment. Vasile > > > Output voltage is about Vmotor-((control voltage/10kOhm)*100kOhm) > > Output voltage is always higher than control voltage. Rise the control > voltage only to a level where output voltage stays about 1V above control > voltage. > > Greets, > Kiste > > > -- > 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.
