# pspice help

#### jamesie1985

Joined Apr 11, 2005
2
Please help I am a first year product design student and am really struggling with my electronics assignment. I must design,create and test an electronic circuit in pspice that will display the correct wind speed reading on an ac voltmeter. the rotation of the propellar produces an ac sine wave of 1mV (rms) and the frequency is directlt proportional to the wind speed where 1 mph = 1hz. the output resistance of the wind speed sensor is 200 Ω and the ac voltmeter has an input resistance of 50 Ω and produces a full scale output for an input rms voltage of 1v. the meter scale is marked linearly such that full scale deflection of the needle should correspond to 100 mph.
any help at all on this would be very greatly recieved thanks in advance james.

#### Brandon

Joined Dec 14, 2004
306
Originally posted by jamesie1985@Apr 11 2005, 12:44 PM
Please help I am a first year product design student and am really struggling with my electronics assignment. I must design,create and test an electronic circuit in pspice that will display the correct wind speed reading on an ac voltmeter. the rotation of the propellar produces an ac sine wave of 1mV (rms) and the frequency is directlt proportional to the wind speed where 1 mph = 1hz. the output resistance of the wind speed sensor is 200 Ω and the ac voltmeter has an input resistance of 50 Ω and produces a full scale output for an input rms voltage of 1v. the meter scale is marked linearly such that full scale deflection of the needle should correspond to 100 mph.
any help at all on this would be very greatly recieved thanks in advance james.
[post=6857]Quoted post[/post]​
Couple clarifications needed.

You said that the sensor produces 1mV rms and that it varies its frequency to measure the speed. How then are you to get full scale deflection from 1v rms when its supposed to stay at 1mV?

Or is it that you need to take the frequency, turn it into a voltage and then measure the voltage and when its 1v that gives you 100 mph?

Also, what class is this for? Will give an idea how this should be solved.

#### jamesie1985

Joined Apr 11, 2005
2
Originally posted by Brandon@Apr 12 2005, 07:12 AM
Couple clarifications needed.

You said that the sensor produces 1mV rms and that it varies its frequency to measure the speed. How then are you to get full scale deflection from 1v rms when its supposed to stay at 1mV?

Or is it that you need to take the frequency, turn it into a voltage and then measure the voltage and when its 1v that gives you 100 mph?

Also, what class is this for? Will give an idea how this should be solved.
[post=6872]Quoted post[/post]​
Thanks for the reply, sorry I was a little unclear, it was the latter where you measure the voltage and when its at 1v it is 100mph. im actually a computer aided product design student and this is part of my module called electronics for product designers. Unfortuanatly, electronics isnt really my strong point and I have already been held back a year due to my failing mark last year. any help, tips or ideas would be very greatly appreciated, thanks again. james

#### Brandon

Joined Dec 14, 2004
306
Originally posted by jamesie1985@Apr 12 2005, 09:59 AM
Thanks for the reply, sorry I was a little unclear, it was the latter where you measure the voltage and when its at 1v it is 100mph. im actually a computer aided product design student and this is part of my module called electronics for product designers. Unfortuanatly, electronics isnt really my strong point and I have already been held back a year due to my failing mark last year. any help, tips or ideas would be very greatly appreciated, thanks again. james
[post=6874]Quoted post[/post]​
Gotcha.

Was there any specification they gave? This could be really easily done using a single micro processor. You would just sample the frequency from the sensor since its so slow its easy to get it accurately. The micro would do a little math and spit out a number to a D/A converter and you got the a DC signal.

Does it HAVE to simulate in pspice or was it just a suggestion to test if it works, etc.

Is this something that you actually have to fully build and present or just design?