# School Project, Where do i start?

Hi,

I hoping that some one could help me with a school project, i am trying to create a stand alone system that will do a couple of things, 1 i need it to produce a wave(square or sin) of 0-12v and about one amp. 2 i need it to change the frequince based on a sencer that outputs 0-5v. and will turn a servo 90 deg. after a switch i tripped. i have a little background in the use of basic stamps, but that was years ago. i willing to try/learn anything, the only problem i dont know where to start, simple would be nice but i will learn anything. once again thank you for your help

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The 12V part is the part i need to control the most, im not sure of the math but i need to turn the 12volts on for 2ms to 8ms and then off for about 2ms to 8ms. the range is for calabrating, because my group is not sure what is will take exactly for the system to work at the right rates. and ya i have the whole scequence figured out. it is all very long set of events. but basicly as the sencer reads a pressure drop, it will change the frequence of the 12v, and the switch and servo will go first and once that goes, the the cirucit will loop over and over again with just reading the pressure sencer and changing the 12v freq. i hop that will be of some help, and i think that the sensor is analog, cuz it outputs a voltage and that is it. and it is aquraticy of 3mv. hope this helps if you need more ask, thanks again, Dan

I think you could start by knowing exactly what you want to do.  For that "wave", for instance, what frequency is required?  The frequency will make a difference to the type of circuit you'll need to generate the signal.  How accurately to you need to control the voltage (12v)?  How accurate must the frequency be?

As for the sensor, servo and switch, you will need to explain more clearly just what you want to do, or what should happen.  Is there supposed to be a sequence of things happening here?  Is the sensor analog or digital?

Thanks for the starting point, tho im sure i will have a few more questions, once again thanks, Dan

You should learn about PWM outputs from microcontrollers. They are great for producing square waves. Also you should learn about voltage comparators. They are great for making that transistion from 5V to 12V. You should also learn about ADC (analog-to-digital conversion) in microcontrollers. They are great for reading analog sensors (and that value can be used to form a PWM signal). You should optionally learn about digital inputs in microcontrollers. They can be used to read switches - but you could do that with an ADC as well. Maybe you should also learn about regulating power since the microcontroller would want that (you would need both a regulated 5V source and a regulated 12V source).

I would suggest using the PICAXE microcontroller since it has EASY control of servo motors built in. Also the programming environment has wizards that lets you calculate which PWM values you need to generate a specific frequency.

Now get busy learning ;-)