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General Mach Discussion / PWM to 0-10v voltage linearity problem?
« on: July 27, 2013, 09:27:43 PM »
Hi there I have one of the boards in the attached file. It proudly states it has on board PWM to voltage converter (I haven't traced the circuit yet but it appears to be based around an opto coupler then into an LM358 op amp. Well it does indeed convert PWM to voltage but sadly not linearly!
My spindle VFD is set to 22000 for ten volts so you would think that 5v would be 11000, but no its roughly 7.5 volts at 11000. The PWM signal is however 50/50!
Can anyone advise me on what the problem might be, and if there's a fix for this board as I assume its the breakout board that has the problem?
Regards
Stu
My spindle VFD is set to 22000 for ten volts so you would think that 5v would be 11000, but no its roughly 7.5 volts at 11000. The PWM signal is however 50/50!
Can anyone advise me on what the problem might be, and if there's a fix for this board as I assume its the breakout board that has the problem?
Regards
Stu