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About duratia

  • Birthday 01/26/1984

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  1. Hi, Why if calculating PWM voltage, it uses V average? Why not using V rms? Does anyone have any reason about it?
  2. Hi, What is the different if I use PWM 1kHz 75% and 100 Hz 75%? Is it true that the voltage is different? Or maybe the energy supplied to motor DC is different? Any comment? Can anyone tell me the relationship?
  3. Hi, I use L293D H-Bridge IC. I have just re-read the datasheet, the max frequency is only 5 KHz. "This device is suitable for use in switching applications at frequencies up to 5 kHz." Once, I read a book that suggest to use more than 20KHz PWM in order to no audible sound can be heard. Is it right? PWM is generated by microcontroller (8051). LM358 is used, but its signal ends on the ADC. It won't affect the PWM, I guess.
  4. Hi, I use DC motor with plastic gear to move thing. When I gave PWM at 23KHz frequency, it didn't move when the direction is reversed. I tried to gave PWM at 1KHz, then it moved fine. Do you know what is the relation between frequency and the voltage in DC motor?
  5. Hi, My recent project is to design motor controller using PWM. I use AT89S52 and L293 H-Bridge as the motor driver. The DC motor is 12 V (DC motor with gear box). If I connect to DC motor, the voltage with 100% PWM dropped to 9.5 V. If I don't connect it to DC motor, the voltage is still 12 V. Is it normal? Anybody can explain why? Do you have any suggestion on how to fix it? Do you also know how to calculate the voltage of DC motor with PWM duty cycle 50%, 75%, 100%? For example, duty cycle 50% of VIN=12V is 6V, is this correct?
  6. Hi, Can you give me more description on how you use RFID to design vehicle tracer? Do you mean like parking system?
  7. Hi, The frequecy is constant. I don't need to change the frequency, it's fixed to 1 MHz (like I programmed now). But, I am still curious how to generate clock using Xtal, because the Xtal can't be "stand-alone". If all of the port/pin of microcontroller has been used and I need 1 pin more, I must generate the clock of ADC using Xtal.
  8. Hi, I use ADC 0809. I am no longer use Xtal for the Clock, but I use timer2 from Microcontroller. But, I still need your advise how to generate clock using Xtal to ADC? The range is 600-1000 KHz.
  9. Hi, I'd like to design the clock for ADC using crystal (1 MHz), how is the connection to the ADC? Do I also need capacitor/extra components? Can you describe me the schematic?
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