I wrote a "voltage divider resistor chooser" - Page 1
Forum section: electronics / general

author: frank26080115
author_rank: Regular Contributor
timestamp: March 03, 2016, 10:15:53 pm
content: It's a Javascript based voltage divider calculator with a twist, use it here:http://eleccelerator.com/voltage-divider-resistor-chooser/You put in your input and desired output, and the values of every resistor in your collection of junk, and it spits out the two resistors that will get you closest to the desired outputI wrote it because I had to make a divider for some band gap voltage referenced ADC and didn't want to buy more resistors. Calculating the traditional way was a little too tiresomeWhat do you think?

author: dcel
author_rank: Regular Contributor
timestamp: March 03, 2016, 10:46:05 pm
content: Atm I am on my phone so i have not checked out your program yet, but will when i get home.I wanted to see if you were aware of ElectroDroid. I have used it for years, since my first android phone. It has the best selection of ele tronics calculators and reference info i have seen, so I bought it. My first paid app. Check it out. No affiliation.Chris

author: frank26080115
author_rank: Regular Contributor
timestamp: March 04, 2016, 06:33:38 am
content: I added two more inputs to optionally specify input resistance and output resistance, to account for things like output load and battery internal resistance

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: March 04, 2016, 07:21:29 am
content: Looks pretty slick. Thanks!What makes this useful is the ability to list you junk bin components and get a result based upon those. Good thinking!I only tested it a hint, but it seemed to work OK.

author: Zero999
author_rank: Super Contributor
timestamp: March 04, 2016, 08:44:02 am
content: It would be good if there was an option to use standard values such as E24 & E96 or a mixture of both.

author: Shadetreeprops
author_rank: Regular Contributor
timestamp: March 04, 2016, 03:32:46 pm
content: This made me think, why is there not a calculator strictly for EE, One that will do all the functions Show all the work, and take any thinking out of it, that would spell wonders for me. I am horrid at the maths.If i make one mistake, which i generally do, that can mean the death of a circuit for me. But If there was a calculator that did every possible formular for just EE, by you just imputing values you now. It will spit out what resistors you need, all combinations of diffrent size ones, one kind of pot you should use, and its ratings.It would be a Specialized tool. Id pay for something like that.something along the lines of. I have a 9v source running a leds in series, and parralle, 2 ea in parralle, wired in series to a total of 10 leds..do i calulate it for the 0.020mA or do i calculate it for 0.040mA since they are in parralle..casue that 2 diffrent resistors.plus thats 1.7v per led, or will it be 3.4v needed for the parralle. so that formula looks something like this R=(Vf-Vs)/IBut like i said math was never my strong suit. only math i excelled at was geometry. but algebra, advanced math, trig calc, i struggled though it, it was like rolling a square up a ice covered slope.I remember blanacing chemical equations, was a struggle till one day something clicked, then there was not a equation i could not balance, unless it was purposley made not to be.. i keep hopeing that click happens with the maths of this..and the universe will open up to reveal its secrets too me.

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: March 04, 2016, 04:44:10 pm
content: There is a pretty cheap app for IOS called EEToolkit. It handles a lot of calculations, and let's you double check resistor or capacitor codes, etc.

author: frank26080115
author_rank: Regular Contributor
timestamp: March 04, 2016, 08:33:34 pm
content: Quote from: Hero999 on March 04, 2016, 08:44:02 amAfter some thinking, I've decided not to add this feature. However, I change the resulting output to show all the results instead of just the best one. This way, you can easily decide if a result is invalid due to tolerances.

author: Zero999
author_rank: Super Contributor
timestamp: March 04, 2016, 10:16:56 pm
content: Quote from: frank26080115 on March 04, 2016, 08:33:34 pmAlright. Here's a list of E96 + E24 values to cut and past into the program but I think you've broken it. Now it doesn't work with these numbers. It did when I tried last night.Code:1010.210.510.71111.311.511.81212.112.412.71313.313.71414.314.71515.415.81616.216.516.917.417.81818.218.719.119.62020.52121.52222.122.623.223.72424.324.925.526.126.72727.42828.729.43030.130.931.632.43333.23434.835.73636.537.438.33939.240.241.242.24343.244.245.346.44747.548.749.95151.152.353.654.95656.257.65960.461.96263.464.966.56868.169.871.573.27576.878.780.68282.584.586.688.790.99193.195.397.610010210510711011311511812012112412713013313714014314715015415816016216516917417818018218719119620020521021522022122623223724024324925526126727027428028729430030130931632433033234034835736036537438339039240241242243043244245346447047548749951051152353654956056257659060461962063464966568068169871573275076878780682082584586688790991093195397610001020105010701100113011501180120012101240127013001330137014001430147015001540158016001620165016901740178018001820187019101960200020502100215022002210226023202370240024302490255026102670270027402800287029403000301030903160324033003320340034803570360036503740383039003920402041204220430043204420453046404700475048704990510051105230536054905600562057605900604061906200634064906650680068106980715073207500768078708060820082508450866088709090910093109530976010000

author: MK14
author_rank: Super Contributor
timestamp: March 04, 2016, 10:23:02 pm
content: Quote from: frank26080115 on March 04, 2016, 08:33:34 pmJust leaving my opinion, here.I tried your program/application, earlier today. Thanks!As other(s) have suggested. It could really do with having the standard, E24 etc, resistor values available as a simple button or some other mechanism. It would make your program, easier and more useful.Think about it another way.If you are buying so many resistors, that you can choose your own value(s). Your program is NOT needed. As they can choose the value they want. E.g. 100,000,000 of 12.75656346364K.Otherwise they are limited to E24, etc etc.But it is your program, to do with, whatever you like with.

author: Aodhan145
author_rank: Frequent Contributor
timestamp: March 04, 2016, 10:28:24 pm
content: I made one in c# a while ago make it so you can choose vin and vout. Then select E12 E24 etc. And list the closest values. I had some fun with making it.

author: Zero999
author_rank: Super Contributor
timestamp: March 04, 2016, 10:31:41 pm
content: There are plenty of online calculators which will do that with the standard E24, E96 values etc. but none that I know of which can use both the E24 and E96 values simultaneously. Some of the E24 values are missing from the E96 set (e.g. 390 & 240) and it would be good to take advantage of them.

author: frank26080115
author_rank: Regular Contributor
timestamp: March 04, 2016, 11:32:45 pm
content: QuoteMy problem is that I didn't buy standard values but I have a big collection of none standard values anyways. I've shifted from a career of "freelance EE" to a full time job. So my resistor buying style has shifted from "bill client for it" to use what I had left over from those days.Quote from: MK14 on March 04, 2016, 10:23:02 pmSo basically, you are asking for maybe a table of values and clicking on a number in the table inserts it into the text box? This is reasonable and I can do it, but it feels so cumbersome than just typing.Or do you want a table of checkboxes?Are you asking me to also calculate a range of output voltages with +5% and then another with -5%?

author: MK14
author_rank: Super Contributor
timestamp: March 04, 2016, 11:46:44 pm
content: Quote from: frank26080115 on March 04, 2016, 11:32:45 pmYes, it can be hard, to change habits, when you are use to things being a particular way. In your current situation, the text box makes the most sense (for you, especially). Because you have got packets of specific values, leftover. (If I understand what you said, correctly).But most people are either ordering from the  or other ranges and/or taking them from standard  resistor kits.I meant something on the lines of...The text box, as it is, and in addition...   Check boxes or similar.So if the text box = 1.5K, and ONLY checkbox  is ticked.The result will be any resistor, in the set {1.5K, 1K, 390, 4K7 .. rest of E24 values, here}But doing it as text insertions is ok as well. All things being equal, I would prefer the check boxes.Inserting it in the text box, would make it harder, to switch it off again. E.g. disable , without lots of messing about, or starting from scratch.QuoteNo. I was NOT going that sophisticated.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 05, 2016, 09:36:38 am
content: Quote from: Shadetreeprops on March 04, 2016, 03:32:46 pmAs an adult,you will be able to "pickup"with ease a lot the stuff you struggled with as a kid.It's not fashionable to say so,but kids are dumb!In fairness,though,Maths teachers don't have time to do things properly,& will progress into "short-cuts" before some of the class have grasped the basics.For instance,if you never latch onto the fact that everything you do with one side of an equation entails doing thesame to the other side,when the teacher starts rabbiting on about "transferring" terms from one side to the other,it sounds like black magic!----It did to me!By the way,your LEDs will all differ slightly in characteristics,so you might be better to give each of them a resistor.And with voltage dividers--draw a bit too much current from the "tap" & your nice "division" won't be correct anymore.

author: Psi
author_rank: Super Contributor
timestamp: March 05, 2016, 09:41:30 am
content: results from best to worst:R1= 1M ; R2= 10K ; Vout= InfinityVR1= 1M ; R2= 15K ; Vout= InfinityVR1= 470K ; R2= 10K ; Vout= InfinityVR1= 1M ; R2= 22K ; Vout= InfinityVyay, Infinite voltage(Used 1e999 as input voltage)

author: frank26080115
author_rank: Regular Contributor
timestamp: March 05, 2016, 04:34:05 pm
content: Quote from: Psi on March 05, 2016, 09:41:30 amJavascript numbers only go up to 1.79E+308

author: profany
author_rank: Contributor
timestamp: March 06, 2016, 06:52:51 pm
content: yes