How to Create a Voltage Indicator Circuit?

So, search for "create a voltage indicator circuit with LEDS'.

http://www.eleccircuit.com/simple-voltage-indicator-by-led-and-zener-diode/

With the price of a microcontroller today I would not approach this task at all in a linear fashion. Using a blocking zener diode to drop most of the voltage down seems like a good idea to me. In theory one could use the Vgs of various Mosfets to discriminate individual voltage ranges but if you're not fabricating the Mosfet itself...

To avoid zener diodes, comparators (linear approach) or microcontrollers (with A/D, digital approach) means you are also avoiding an abrupt change from one state to another state. Often the simple approach is best. But it sounds like you are trying a simple approach that is functionally not able to do what you want it to do.

From the little bit of information provided I suspect that:

1) If your requirements are for "dead" vs. "not dead" your approach might be worth working on.

2) If your requirements are for measuring voltage (I see decimal points in your posting so I think you are here) then you should use Mr. Google for terms like "comparator", "operational amplifier", "zener diode", "voltage reference" and other terms that you will find during initial Googling.

Do your work and people at CR4 will probably help you. Please be warned, if you don't do your work and post dumb questions you will probably get responses that match your questions.

Please take note iof my question as I have mentioned that I'm a FIRST YEAR student. Sorry to hear that you genius have never been there but there is a initial learning state that you know so little about a topic(espcially all the fundamental concepts) that googling does not help since most of the articles assume some kind of background knowledge. For example, yes, my approach is "dead" or "not dead". So how does that make this worth the work? If you're not too knowledgable to explain some simple concepts to a beginner trying I learn, that is.

I didn't even read your entire paragraph...hahaha, you're gonna be a real hit around here. if I could offer you you a clue....be nice to redfred, he's a valuable resource, genius or not

Since you are a first year student I will freely give you a bit of advice. The knowledge you earn is far more valuable than given knowledge. So here is some given knowledge for you.

An LED is just a light. It is a very efficient but highly non-linear light. Like most diodes they tend to follow the Shockley diode equation. The amount of light that an LED produces is a nearly linear relationship to the current flowing through a diode but there are two complicating factors for you. First, the relationship between current and voltage of any diode is highly non-linear. Second, the human eye's sensitivity to light is even less linear than a diode's V-I curve.

So, some other part of your circuit design must decide if a battery is "Good". Your LED will reflect or announce this decision, not make this decision.

Hint: Think about all of the states your battery detector should possibly every be in.

So, even a mediocre first year student needs to master the concept of:

How to Search the Internet - Hannon Library so that they can understand the:

Fundamentals of Light-Emitting Diodes so they can, someday, do their own projects.

So, read up on the Fundamentals of Light-Emitting Diodes so you won't have to ask questions so fundamental.

So, good luck with the project.

"So" is not widely accepted as the beginning word of a technical discussion.

So, yes it was a long time ago.

So long ago that virtually every technical publication ever written was not available, free of charge, to anyone with the gumption to look for it on their laptop/smart phone.

I actually do understand that times have changed.

So, good luck in your quest for artificial intelligence.

I feel like a crossover here.

Having gone back to school late in life I have never thought to ask a question involving my courses. I've read the rules, and they're pretty clear.

I do enjoy just reading about the topics that touch on my studies, and the disciplinary actions taken by the group when these moments come up.

I actually enjoy Lyn's moments when he calls out an obvious text book request.

Forgive me for my no value added comment.

You called it how you see it, no problem there. I almost gave you a GA for it!!!

Why should he bother. What can you offer to the discussion?

Anyway, if I was to want to use a voltage divider resistor, I would use a potentiometer, and dial it until you get the results you want. Then measure the resistance of the pot and replace it with the right resistor.

Too practical redfred?

GA.

That's precisely the chip I had in mind! It worked nearly 40 years ago, and still does!

(And I was thrilled to know that I remembered the number even before I saw your post!)

http://www.ti.com/lit/ds/symlink/lm3914.pdf

That chip's been around for ages.

I remember having to learn how to design an A/D converter and then using discreet logic to change that digital number into a bar display, same with 7 segment displays.....

....then as if that wasn't cruel enough, when the work was done and proven on a bread board (get a bread board learner135) the tutor would say forget all that bother and just use these chips. The hard work's been done bwahaha)

The way we learned.

If I was the OP I'd just use something similar to one of these with an "analogue" bar indicator:

Excellent suggestion, that was the chip I used to build precisely the same thing as the OP is looking for as a high school project. The datasheet had very detailed information, and even showed how to 'bridge' the chip with another for a 2-decade indicator.

Here's a cheap and dirty clue, voltage dividers. Good luck.

A long time before computers and the internet I was asked to design a similar circuit. My best resource was the applications notes from National Semiconductor.

They had a neat A/D chip with ten outputs to drive LED indicator. The handheld device was measuring 5000V generated internally and applied with a SS test probe.

It took me a month to design the circuit and another month to do the mechanical packaging. Upon completion We built several thousand of these testers. Oh yeah when I started that job I had flunked Gr12 so in effect I was a highschool dropout.

However I never let schooling get in the way of my education.

Good luck!

Elnav

All that's needed here are resistors and LEDs. Think about what you already know, the LEDs turn on at a certain voltage. You can make voltage dividers with resistors. I assume you don't need super precision. I did this once years ago for a crude high voltage meter using NE2 neon lamps.

Trouble is LEDs don't just "turn on" at a certain voltage. They begin to glow (at a certain voltage), very faintly at first, and get brighter and brighter (not linearly) as the voltage across/current through them increases. Not trying to teach my granny to suck eggs - just pointing it out for the benefit of the OP.

I have no idea why someone marked this OT. I think it's a perfectly reasonable reply!

_{(except for 'your' should be 'you're'.)}

'You're' is a contraction for you are...just which YOUR would you change?

Good point! I should have specified:

"Not sure if your into electric rc cars/trucks..."

That one.

You're wrong!

Although I resent your attitude towards the very people you are asking help from, I will offer this. http://shop.advanceautoparts.com/p/otc-charging-system-analyzer-otc7200/17632202-p

This is an automotive charging system tester that uses four LEDs to determine the different functions. This is designed around a nominal 12 volt system. But the design work is already done for you. RESPECT is earned, and the people you have dealt with here have earned it.

Relax. He just does not want to be talked down to. Is he a troll? No, he is NOT. So he replied in the same tone as he was talked to. What is wrong with that? Of course, there are times when I have not been as polite as I could have been. And once I was dead wrong. So, I have some sympathy. Not much, but some. Good link BTW. I'm a gonna buy me one of those!

I am now on my second one. I guard it a little better now. The first one is still under someone's hood. (Reward for the finder-$15) It does not do everything one needs for automotive work, but it has never lied to me either.

I am assuming (not always a good thing!) that the need for voltage indication is to deduce the capacity of the battery at this point, but as with the chemistry, the OP did not tell anyone the real reasons behind his unfriendly request....so I may be entirely wrong - this OP is sadly lacking in even being able to supply simple relevant data, without help from others.....

If for example it is LA chemistry. Its voltage varies relatively quite a lot with regards to charge level and relativley unsophisticated circuits can be used.

Other battery types operate from full to empty over a relatively tiny voltage change/range and need more specialized circuitry to provide proper indication, assuming that is his need, but we still don't know for sure!!

DUUUUUHHHHHHHHHHH!!!!

My personal take is that anyone REALLY interested/ knowledgeable/learning in this area would have been able to design a working circuit while still in high school or equivalent. Maybe even sooner....

Or at least able to search the internet for help alone!!!

Here is a link where most battery types can be observed and learnt about:-

Battery_types

Also, for someone already in the Uni, there would/should be no need to get help from CR4.......or to get unfriendly with other CR4 members.....therefore no further help from me personally.....byeeeee

You are absolutely right! There are a host of different batteries, each with its unique characteristics.

look at an LM3914 series chip as a possible solution to your problem.

I made a product years ago for vehicles that used 6 led's in series, they worked very well and were also an indication of vehicle charging system. They were designed for about 14.5 volt max that being a charging system and if the alternator was failing the diodes would reduce in intensity or not illuminate. This was not a winning situation over all and I had to have a circuit designed that had a voltage regulator built in. It worked above expectations and made me a solid profit.

Point I was making is if you have known values design for the high side and as that figure decreases the diodes will not be as bright.