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 1 Using Arduino / General Electronics / Re: Create PWM with amplitude of +9v and -9v on: June 23, 2011, 10:30:47 am I actually already tried to send a analog signal to the coil, but there is a problem because while the current in the coil is 0, the arm is not stable at all, so that's why i need a real PWM on the coil in a pretty high speed. While i'm giving a +-9v vith Duty Cycle of 50% directly on the coil, the mean voltage is also 0 byt the arm is stable because of the hihg frequency.
 2 Using Arduino / General Electronics / Re: Create PWM with amplitude of +9v and -9v on: June 23, 2011, 10:13:29 am OK, sorry, i will start over... I am trying to drive a Hard Disk actuator arm. I soldered two wires to the Arm's coil which placed between the magnets. While i'm connecting one of the wires to +5v and the other to 0 in external PowerSupply, it takes the arm to one side due to electro magnetic field which created by the current in the coil, but if i want the arm to go to other side, i need to switch the wires or to decrease the voltage to be negative (current will flow to another side). I need quite precise control of the arm, so i want to use the PWM with a high frequency to control the situation of the arm by changing the Duty Cycle on period of 500Hz.
 3 Using Arduino / General Electronics / Re: Create PWM with amplitude of +9v and -9v on: June 23, 2011, 09:30:10 am I know that Ardumoto shield can provide a negative DC (-9v) voltage while setting: digitalWrite (dir_a, LOW), and positive DC (+9v) while setting: digitalWrite (dir_a, High). Therefore i can get a PWM of +-9v without any additional transistors, but i don't know if i can do it in high frequency.. How can i make delay of HIGH and LOW to be less than 1ms.
 4 Using Arduino / General Electronics / Re: Create PWM with amplitude of +9v and -9v on: June 23, 2011, 08:55:18 am I need to drive actuator, which is about 500-600mA. It is for My final project in university.
 5 Using Arduino / General Electronics / Create PWM with amplitude of +9v and -9v on: June 23, 2011, 08:43:45 am Hi, I have an Arduino Duemilonove and Ardumoto shield. Is somewone know if it is possible to create a +/-9v PWM with frequency of about 50Hz using those resources? I also need to control the Duty Cycle..
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