USA PE Exam Calculators fx-115, fx-991, HP 35s, TI-30X, TI-36X

[HyMech]

First Post here!

Which is the best calculator for the PE exam?

I'm a mechanical engineer but always had an appreciation for electronics. I have several EE's in the family and I have even taken a few college level EE courses. I earned a Professional Engineer (PE) license in Mechanical Engineering in the USA through a combination of education, experience and passing of an 8 hr exam. I work for a power company and have been bored at work lately so I'm thinking I may study up and take the PE exam in Electrical Engineering. Its a big challenge that I may never finish but eh.

When I was working on a bachelors degree, I used a "TI Voyage 200" which died a few years ago. I sent it into Dave for EEVblog #715 - Mailbag https://youtu.be/v4iFgukMwsI) I recently bought a "TI Nspire cx CAS" which I am still getting used to.

However, the only a few simple calculators are allowed on the PE exam:

• Casio: All fx-115 and fx-991 models (Any Casio calculator must have “fx-115” or “fx-991” in its model name.)
  Hewlett Packard: The HP 33s and HP 35s models, but no others
  Texas Instruments: All TI-30X and TI-36X models (Any Texas Instruments calculator must have “TI-30X” or “TI-36X” in its model name.)

Source:  https://ncees.org/exams/calculator

I want to use the best one on the PE exam and then recommend to other PE hopefuls. There are a few posts online but they really lack any substance, mostly just comparing the calculator specs.

So which is the best?

When I took the Mechanical PE exam in '07 I used the HP33s but I loaned it out and never got it back. It which seems to have the same firmware as the 35s that I recently bought. I found it to be a great calculator. However, it is nice to have two calculators so after watching Dave oogle over the fx-991 I bought that as well.

I might do a full comparison one day but after working a few problems, I was surprised to find the fx-991 crashes when doing fairly simple problems with complex numbers.

Consider this problem from my old circuits book:

Find Equivalent impedance R1=2, R2=3, R3=6, C1=-j2, L1=j4 

_____________R1__________________
                                    │                     │
                                    │                     │
                                    R2                   R3
                                    │                     │
                                    │                     │
                                    C1                   L1
                                    │                     │
____________________│___________│

Zeq= 2+ 1/(1/(3-j2)+1/(6+j4))

This crashes the fx-991(in complex mode) but is done easily on the HP35s in either RPN or ALG mode.

[thm_w]

The quality of the TI-36X keys are horrible, and conversion from polar -> polar etc. takes more steps than I'm used to (shift, complex, select 3). Sharp EL531 had dedicated keys, I don't know how casio compares. Maybe there was an easier way but I didn't see it. I suspect there is a lot of functionality in the calculator that would make life easier, but I didn't investigate. Either way it was enough to get through FE without any issues.

I would choose whatever calculator you are most comfortable with.

edit: tested that equation on TI-36X and its fine as expected. Something to keep in mind some calculators are more strict with parenthesis than others. Also remember now to get 'i' you have to press the pi key three times which is not too convenient (pi -> e -> i).

[0culus]

I have no experience taking PE exams (fortunately my field doesn't require such exams!), but I do have an HP-35s. Purely from a usability standpoint, it's not exactly as nice as a vintage HP calculator in terms of how good the keys feel, but the keys are a LOT nicer than virtually any other new calculator on the market. And it has RPN, does complex math, and a lot more that I probably don't use. It is rather clunky for working with different integer bases, but that's what my HP-16c is for.