Calculator recommendation? - Page 1
Forum section: electronics / general

author: MikeK
author_rank: Super Contributor
timestamp: March 06, 2021, 06:29:09 pm
content: I'm looking to get [yet another] calculator. But I want one that can handle equations. As an example, I recently was calculating a lot of inductor values from measured frequency and known capacitance in an LC tank circuit. So I would have wanted to enter the formula, and then just enter F and C to arrive at L. And be able to do that multiple times by just entering F and C. I don't need some really expensive unit, or graphing.

author: Refrigerator
author_rank: Super Contributor
timestamp: March 06, 2021, 08:59:06 pm
content: I've been using my TI-82 for stuff like this, but you would need to code a TI-BASIC program to calculate stuff for you.For example i've written programs to convert HEX to BIN, DEC to HEX and so on. I think i might have even had an LC tank calculator set up back in highschool during physics class.Basically if there were any repetitive calculations i'd just write a program to do it.Not sure if there are any calculators that let you plug just an equation in.

author: MikeK
author_rank: Super Contributor
timestamp: March 06, 2021, 09:05:53 pm
content: Well, maybe not plug an equation in, but to do something like this:1. I enter a frequency value.Calculator does these steps:2. Multiply by 23. Multiply by PI4. Take the inverse5. Square it6. Divide by 10-12(which is my capacitor value of 1000pF)

author: MikeK
author_rank: Super Contributor
timestamp: March 06, 2021, 09:06:31 pm
content: TI-82 might be good, I'll check it out, though.

author: Someone
author_rank: Super Contributor
timestamp: March 06, 2021, 09:55:59 pm
content: Most of the graphing calculators will have a numerical solver, they're cheap second hand and just ignore the other bits you don't want?If you really really want no graphing for some reason there are a few intermediate calculators, on the market right now is the TI-36X Pro....But it only has a limited set of variables, no physical constants, and needs more button presses to do the solving. So a modern graphing calculator doesn't look so bad.Quote from: MikeK on March 06, 2021, 09:06:31 pmThats one of their few graphing calculators thatdoesn'thave a numeric solver, possibly the worst combination of all features/choices for what you stated.

author: TimFox
author_rank: Super Contributor
timestamp: March 06, 2021, 10:07:17 pm
content: I personally ignore the programming capability of calculators (preferring to use Excel on a laptop), but this company has modern clones of classic -hp- calculators, with modern electronics and lithium batteries:https://www.swissmicros.com/They feature RPN logic and real pushbuttons. Their newest models seem to have nailed the pushbutton design. The physical hardware is somewhat re-arranged from the original designs, but the functionality is correct and they can be programmed in the original manner.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: March 07, 2021, 04:29:38 am
content: Would this help?

author: MikeK
author_rank: Super Contributor
timestamp: March 07, 2021, 04:50:48 am
content: No, not looking for an app or website. I want a handheld calculator that I can program with simple steps.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: March 07, 2021, 05:50:27 am
content: Then a TI-whatever for like 5$ from a garage sale. That's what I have lying around, a TI-83.

author: rfclown
author_rank: Frequent Contributor
timestamp: March 07, 2021, 06:55:18 am
content: Quote from: MikeK on March 07, 2021, 04:50:48 amI too am answering against your stated wishes, but here is what I do. I loath computer GUI calculators. A mouse has to be the worst cacluator user interface ever. I used to have a Radio Shack pocket computer (that someone gave me) that I could program simple things like you want. Long abandoned. I wrote a C program to make my own calculator in 2002. It just operates on a command line, no GUI. When I wanted a new function, I'd add it. I made it so that can run a sequence of functions (like what you want), but in the end I never use that. Over a year, I had added all the functions that I routinely want to do, so I didn't have to program. I haven't modified it since 2003. I keep a CASIO scientific on my desk, and use the C program for more complicated stuff. So if I want to see what inductor resonates with a 1000pF cap at 100MHz (like your example), I type:ca (my program name in a DOS window or Unix shell)fr100MHz1000presIt uses a RPN stack, because that made it brainless to write the program (not that I'm a fan of RPN calculators). I put all the conversions I normally do like S to Z, peak to RMS, dBm to watts, etc. (s2Z, Z2s, p2r, r2p, d2w, v2d, ...). Everything is complex.Anyway, that's how I solved the problem for myself. I only wrote it for me; have never shared it. You can have it if you'd like. Compiles on command line with gcc.

author: emece67
author_rank: Frequent Contributor
timestamp: March 07, 2021, 09:07:48 am
content: .

author: Refrigerator
author_rank: Super Contributor
timestamp: March 07, 2021, 09:26:55 am
content: Quote from: Someone on March 06, 2021, 09:55:59 pmTI-82 is also very old and slow, i just have mine because i found it at the flea market for 3 bucks.I'd look for something newer like TI-84 for example.There are also other programmable calcs, for example i also have a SHARP EL-9900, but these particular ones are plagued by defective LCD ribbon cables and mine is no exception, so i'd avoid these. But it is about 2 to 3 times faster than my TI-82 STATS.But that's just as an example that TI are not the only ones producing calcs like these.PS: you might also find calulator emulators for your phone, but those might be a bit awkward to use.

author: HighVoltage
author_rank: Super Contributor
timestamp: March 07, 2021, 10:10:50 am
content: Another vote for swissmicrosThey have really nice calculators, based on the old HP system.

author: mathsquid
author_rank: Frequent Contributor
timestamp: March 07, 2021, 08:53:42 pm
content: I have a Casio FX-6300G that can do this sort of thing. I'd imagine any vintage programmable scientific calculator (Casio and Radio Shack brands especially) can do it. I don't think that most modern non-graphing calculators can do this.(Technically the GC-6300G is a graphing calculator, but just barely.)

author: MathWizard
author_rank: Super Contributor
timestamp: March 07, 2021, 09:34:18 pm
content: I have a TI 36xpro, which is surprisingly cheap but great, it's easy to make an eqn in the display, w/ variables in memory. IDK if u can use the table and stats w/ eqns that way

author: MikeK
author_rank: Super Contributor
timestamp: March 07, 2021, 09:39:03 pm
content: Quote from: mathsquid on March 07, 2021, 08:53:42 pmHi mathsquid,Could you please explain how it would do what I want, from the steps I listed in Reply #2? Could I just enter a new value for Frequency and it would recalculate the L?-Mike

author: Someone
author_rank: Super Contributor
timestamp: March 07, 2021, 11:14:30 pm
content: Quote from: MikeK on March 07, 2021, 09:39:03 pmYou might still be thinking more of programmable, and producing a set of steps. That is one of the ways to achieve this sort of result:Write a short program that asks for the specific known variables and then calls the equation to find the unknownEnter the equation on the screen and use variables/history to bring it back up and quickly recalculateUse a numerical solver that will find a solution for any variableIts that last one which is so powerful, being able to go back and forth between different unknowns. Common: Whats the ideal component value for the cutoff frequency? But I only have E12 series, given their rounded values what would the actual cutoff frequency be? Having to go through the equation in two different solutions.A solver can do that much more efficiently as you don't have to edit/change/move anything. Below is an example screen from a TI-83? It shows the equation you entered and all the variables below it. Enter the values you do know and press solve on the one you want to calculate. Simple as that (the TI36x mentioned above has a smaller screen and doesn't show the equation at the same time?).

author: newbrain
author_rank: Super Contributor
timestamp: March 08, 2021, 07:30:05 am
content: I know it's not the same quality as the classic ones, but I use an HP35S.Swissmicro are nice, but a bit expensive, and 'real' used HPs are not easy to find.It's good enough for my purposes, and has the exact function the OP is asking for:In equation mode (EQN) one can enter a formula with variables, and it wil ask for the unknowns.It can also solve for any variable if the equation is entered as an equality.RPN (algebraic too) and no graphics, programmable, in addition to the equation mode.A bit clunky for base-n calculations.When not close to it, i use free42 on my phone.When the calculation is more complicated or needs more than a simple program, it's time for a python jupyter interactive window in VSCode.

author: emece67
author_rank: Frequent Contributor
timestamp: March 08, 2021, 09:40:36 am
content: .

author: mathsquid
author_rank: Frequent Contributor
timestamp: March 09, 2021, 03:47:25 am
content: Quote from: MikeK on March 07, 2021, 09:39:03 pmIt's been a few years since I've done this, but I think that programming these vintage Casios is more like setting up a macro that can be reused. Rather than trying to remember it, I'll point you to a manual for the calculator (http://www.usersmanualguide.com/casio/calculators/fx-6300g), and I'm attaching a few screenshots of the relevant section.

author: CH1
author_rank: Newbie
timestamp: March 09, 2021, 05:44:19 am
content: I'm gonna get roasted for this, but I do think the 991es or 991ex from casio has one of the easiest interface for variable subbing and equation solving, since everything is shown as if its written on paper.I do own a Swissmicros DM42 and I use it much more often than the casio; for simpler calculations, RPN really can't be beat. But when I see an equation too long to fit in my head and don't want to wait for MATLAB to open, I just reach for the casio.

author: bd139
author_rank: Super Contributor
timestamp: March 09, 2021, 08:01:34 am
content: I use mostly excel. And for everything else it’s an HP35s. The 35s is programmable RPN so you can enter a few keystrokes to record a program then execute it many times for different values. Plus they’re new and you can still get them without having to argue with second hand ones which are invariably broken or smell of cigarettes.

author: MikeK
author_rank: Super Contributor
timestamp: March 31, 2021, 12:00:36 am
content: Just got a TI-83 off Craigslist, for free.Just have to fix the battery-to-PCB contacts.

author: TimNJ
author_rank: Super Contributor
timestamp: March 31, 2021, 04:02:07 am
content: What kind of phone do you have? I use Archimedes for iOS. It’s the best implementation of “visually perfect” input I’ve ever used. Does algebra no problem. I’ve made enough detrimental algebraic rearranging mistakes that I really appreciate that it just let’s you put in an equation in the form you know/remember, and can solve for you. Some old school engineers would probably scoff at it, but whatever.

author: Dubbie
author_rank: Unknown
timestamp: March 31, 2021, 04:17:34 am
content: I really like desmos on my phone for graphing.For general purpose arithmetic, I like my swissmicros DM42 HP clone.

author: tooki
author_rank: Super Contributor
timestamp: March 31, 2021, 04:06:50 pm
content: Take a look at HP’s current graphing calculator, the HP Prime. I think it meets every one of your requirements.I have programmed a number of things into mine, eg.PAR3(x,y,z)to calculate 3 parallel resistors. Internally, that expands to 1/((1/x)+(1/y)+(1/z)), for example. (Except that you can enter and edit your custom functions with a full “textbook” entry with visual fractions, which this forum supports but I don’t know the syntax for... haven’t learned latex yet!)You can download a full-featured HP Prime emulator for Mac and Windows for free, so you can try it out as much as you want before buying. It behavesexactlylike the physical device. The emulator (and all the manuals, the computer connection software, etc) is on HP’s FTP server:ftp://ftp.hp.com/pub/calculators/Prime/(connect as guest)It’s not 100% perfect, but I love mine. It’s got a great keyboard, a glass touchscreen that’s actually useful, and it’s fast. It’s also very thin, which is nice.

author: VK3DRB
author_rank: Super Contributor
timestamp: April 01, 2021, 09:32:33 am
content: Turn your telephone into a decent calculator...RealCalc. Brilliant.https://play.google.com/store/apps/details?id=uk.co.nickfines.RealCalc&hl=en_AU&gl=USPrefer HP programmable?https://play.google.com/store/apps/details?id=com.thomasokken.free42&hl=en_AU&gl=US

author: bd139
author_rank: Super Contributor
timestamp: April 01, 2021, 09:37:52 am
content: Quote from: tooki on March 31, 2021, 04:06:50 pmThis is where the prime is inferior annoyingly. If you wanted 3 parallel resistors on the 48/50 you could write a simple program saved as RP<< 1/X SWAP 1/X + 1/X >>This could be applied to any number of resistors in parallel by using accumulation so say 4:1000 2200 4700 8200 RP RP RPSo you build the program for two operands and then use the bottom of stack as the accumulator. A huge number of programs and functions can be turned into simple dual arity accumulator functions like that which the stack makes easy to handle.I did write an APPLY function which would take all the stack values and apply a function N-1 times to it so you could just fill the stack up with resistors and then do:‘RP’ APPLYAnd it’d merrily chunk through them all.