flow rate

Hello Everybody,
Please help me regarding my project

In my project I have to control the flow rate(Air) by using proportional valve. The proportional valve is proportional to the voltage

For 0v valve is fully closed
For 24v valve is fully opened

By varying the voltage 0 to 24 v I have to control the valve position using micro controller

For different elements I required different flow rate, this element I will enter the through

the key board (programmed) according to the element Micro controller should control the

flow rate.

How to vary the 0 to 24v using micro controller

Please provide me suggestions for this project

Thank you
Regards
chandu

hi chandu,
the first step in ur project would be to interface the keyboard to the uC.for the output u will have to interface a DAC to first convert the digital output from the uC to an analog signal of say 0 to 5V level. the last stage would be to scale this output to the 0 to 24V range. the tricky part is that if u are interfacing this output to a valve, then the last stage output must be able to source a considerablely large amount of current.
So i suggest u first complete the first two stages first (keyboard and DAC interfacing)and then we can talk about the last stage.
u will find the details of the interfacing in the tutorials section.
good luck :-)


P.S. another method of generating an analog signal is to generate a suitable PWM signal (vary the duty cycle according to preset values) and then converting it to an analog signal using a proper filter circuit.

Thanks for the immediate response

I am planning to use PWM for my project

How PWM signal (vary duty cycle) will convert in to the analog signal

Micro controller output PWM pulses will be 0 to 5v

How this 0 to 5v pulses will convert in to the 0v to 24v


Regards

chandu

use L293D + PWM, as you keep on changing the PWM width from low to high o/p voltage will vary from 0 to 24V.

L293D is perfect for generating PWM till 30V. try it..

Hi
Thanks for the reply
For this project I am planning to use LPC2106 it has in built PWM channels.
Can I interface LPC2106 with L293D, because LPC2106 logical high is 3.3V
This logical high voltage can switch the L293D or not
How to interface LPC2106 with L293D

Regards
chnadu

minimum voltage level for Logic high for L293D is 2.3V which is fine for 3.3v logic

hi every body

I want generate the different duty cycle PWM pulses using LPC2106 PWM channel
I read data sheet but I confused with PWM registers configuration

Please provide me one example code for 70% duty cycle PWM pulse generation using LPC2106(crystal frequency is 12MHz). How to calculate the values

Thank you

Regards

chandu

why can't you use Power Amplifiers in this stage.

hay

what is the use of Power Amplifiers at this stage

Regards
chandu

Hi nattu/chandu/naresh,

pl. go thru the following thread which discusses a similar topic :

http://www.8051projects.net/forum-t10341.html


Arun