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I want to make current pulses, the intensity of the pulses must go up slowly during a period of time until it reaches a maximum value... I have thought of using a microcontroller to make voltage pulses using pwm then by using a voltage to current converter i can get current pulses.. I understand the meaning of pwm that we're changing the off-on time but i need to know what do i get as the output? I mean do i get values between 0 and 5 v? *I don't know if the whole thought is correct tho... I appreciate any other thoughts

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    \$\begingroup\$ Ohm's law I = V/R \$\endgroup\$ – JIm Dearden Mar 16 '17 at 17:17
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    \$\begingroup\$ A PWM can be a solution and it also could not. It depends in many other factors, mainly, what is 'slowly'. Also, what granularity you expect. And the whole design is a big question if you don't tell some more details, i.e. current values. \$\endgroup\$ – Claudio Avi Chami Mar 16 '17 at 17:33
  • \$\begingroup\$ I'm trying to make a nerve stimulation device, I took the idea from an already made device and I'm trying to build the circuit.... the device must deliver biphasic current pulses with a specific frequency equals 60 Hz and a fixed pulse width equals 300 microseconds... the intensity increases gradually by a step up between 30-50 microamperes till it reaches the maximum value which is 16 mA.... I have in mind how to achieve the fixed pulse width and the biphasic form... and I got the thought of PWM and the converter to achieve the increase in current pulse \$\endgroup\$ – user142362 Mar 16 '17 at 19:18
  • \$\begingroup\$ @ClaudioAviChami I need to get biphasic current pulses with a specific parameters... the maximum current is 16 mA... it must goes up from 0 to 16 mA by a step up in current between 30 to 50 microA \$\endgroup\$ – user142362 Mar 17 '17 at 17:23
  • \$\begingroup\$ 16mA is quite dangerous for nerver stimulation. I hope you know what your are doing \$\endgroup\$ – Claudio Avi Chami Mar 17 '17 at 18:24
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See PWM (Pulse width modulation) is a technique used by micro controllers (such as Arduino) which is used to generate analog output(results) by using digital means. Digital output is either on (or 5V in Arduino) or off ( or 0V). PWM techniques uses on and off pattern to stimulate analog results. For this first the on state is activated for a small period of time... and then off state is maintained. This is repeated several times (500 or 1000 times... This can also be changed by programming in Arduino). Thus this appears as an analog effect to our eyes and we think that it is giving a output between 0V and 5V. But actually it is digital signals only which are on and off during a cycle ( called duty cycle.. And in this the proportion of on state in each cycle is shown with a percentage) and this cycle is repeated several times. A 0% duty cycle is analog off (or CAN be called digital off too) and 100% duty cycle is complete analog on (or CAN be called digital on too).

Study the graph below to get more idea. PWM graph with different duty cycles. ]1

For more information go to the Arduino website and search for PWM.

Good day!

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  • \$\begingroup\$ Thank you! So it doesn't gives values between 0 and 5v, in this case the voltage to current converter will be useless to give an increase in the current, right? \$\endgroup\$ – user142362 Mar 16 '17 at 19:27
  • \$\begingroup\$ The GPIO output of a microcontroller will be a binary choice of high or low voltage. You can low pass filter a discrete-voltage PWM signal to get a variable DC voltage. By doing this, you are create a voltage that is the average of the PWM signal's voltage over time. This would be considered a form of digital to analog converter. \$\endgroup\$ – user2913869 Mar 16 '17 at 21:51
  • \$\begingroup\$ I've been reading about what you suggested... seems like it might work this way.. I'll look more into, thank you ! \$\endgroup\$ – user142362 Mar 17 '17 at 13:06

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