calculation help for digital to analog converter

[garoken]

and for the speed do i need to times 3500 to the 0.366211 value cause i was told by my instructer to do so..

 

[iant]

your calculated value
0.366211 is (RPM/BIT)
lets check that first
0.366211 * 4096 = 1500 All good
so lets work out the mA for the RPM
16/1500 = 0.01066667 mA per RPM
so x 200 = 2.133 mA above zero
so add the ofset of 4mA
6.133mA
same values different approach

The most important thing with calculations is to include the Units.
NOTE :- 0.01066667 mA per RPM
so 1200 * 0.01066667 = 12.8 mA

 

[iant]

your 3500 number was not RPM it was BITS
very important to use the correct units

 

[garoken]

err how did you get 1200

 

[iant]

I cheated
1281.74 * 0.010 = 13.6719 mA

 

[iant]

normaly you would scale something once
but
16/4096 * 3500 = 13.671 mA

 

[garoken]

so for my answer is there anything i can improve on??

 

[iant]

when I was learning to be an Electrician
we had two things drilled in to our small brains.
1. use the units always
2. show all stages of the formulae.
and
check the result with an approximate value
eg.
4096 = 1500 = ratio of 2.7 : 1
200 x 2.7 = 546 = about 1/3 of 1500
the value looks correct see

 

[garoken]

wow thanks alot your answers has been really helpful!!

 

[iant]

well I will accept you getting 100% for your exam
I never did LOL

 

[garoken]

wow thanks!!