Battery Level Indicator

Trying to build me a battery status or level indicator, using the LM339 series IC. I am just not that familiar with this IC. I want to make this using 3 red LED's, 3Yellow and 3 green or using a bar graph LED. Any advise on how to hook this LM339 up?Thanks

Posted by dominick.j.pezza 3 years ago

Sound level meter?

Does anyone know how I can build a simple sound level meter with a light that will come on at a certain sound level?

Asked by pennsteve 6 years ago

USB Level Shifter help

I need help trying to replace a RS232 level shiftre with an USB plug. Any ideas?

Posted by Woody 10 years ago

Electronic Level

I need to level a 32' long machine. Lengthwise is easy, but along it's width is a pain. I have to check in about 8 places along the machine. This takes awhile to do with only one precision level. Since these levels are about $120 each it is not realistic to buy eight. I need to save time and effort. I was thinking of trying to build a bunch of electronic levels to place in their designated areas so I can find the "level" of each area without moving a level to it. Any ideas?

Posted by Monger 9 years ago

Bluetooth Water level for smart phones

I need some help in making a bluetooth water level that uses standard float switches.  Once a float switch is triggered it would close or open a circuit then the data of which circuits are opened or closed can be used to determined the level in the tank. This will be sent via bluetooth to a mobile device were i will develop an app to visualize the data. Please i need info on how to setup the electronic components.

Posted by Higrade 4 years ago

Bluetooth Water level for smart phones

I want to know how this would be accomplished PLEASE. Looking to make a bluetooth system that sends water level of a tank to a smart phone. I would think the most cost effective way to do this is by using a bluetooth module and float switches. The module would send three levels full, half and empty, so say all float switches are triggered it would be full, only one it would be half and if none it would be empty. What do i need to build this.

Posted by Higrade 4 years ago

How to make a water level indicator?

I want to make a water level indicator without sensors or ic. I want to make it with switches. I have a switch in which we have to press the switch to turn it on and if we leave it, then it turns off. So i can connect the switches with the leds and power it with a 9v battery. Please can you make the wiring diagram for this.

Asked by ckkartik 5 years ago

Electronic water level gauge for well

I have a 32m deep, 95cm diameter well, that is covered with two heavy concrete covers. The water depth is about 20m down from the surface. I cannot easily access the well to sound the depth or visually check the water level. I would like to build an electronic water level gauge that will tell me the amount of water in the well. I can then regulate watering accordingly. It was suggested to me that I use a washing machine pressure transducer but I have no idea of the circuit required. A refined solution would send data to my PC !!!! I have 240v AC supply to the well pump. Any ideas? Steve

Posted by SteveG31530 9 years ago


So this is what I came up with eagle for the lm3914 can someone please verify if this will work as intended.

Posted by dominick.j.pezza 2 years ago

Large Scale Water Level Indicator

Hey everyone, I hope im posting this in the right spot.  I run a large farming operation and get my water from a well that pumps into a large storage tank about 10 feet deep and 6ft diameter.   Because the well is very old I'm not able to add things like a float that will turn it on or off for me so I'm constantly having to check the well though out the day and if the cows are more thirsty one day they can drink the storage tank dry and that causes me problems with my pump, or if i leave it to long it will overflow and it makes a terrible mess. So im wondering if there is a way that I can wire up a water level indicator in the well-house and have a light board in my house that shows me the level of the well.  So for a 10 ft deep well id have an led light for every 1ft or so and when the water level gets to the top foot a buzzer would go off and when it hits the bottom foot or 2 ft then a buzzer would go off.  Ideally a wireless transmitting to the house would be best but I have no idea how that could work.  And wired would be hard with the well house being a few hundred feet away from my house.  I've done a lot of googling and haven't found anything that would suite a large scale water tank like this.  I purely want to be able to see in my house where the water level is and have it warn me when its too high or too low.  I apologize since i don't have a lot of experience in electronics.  Any help is greatly appreciated as i have no idea where to start or if its even possible.  Thanks guys!

Posted by rpfarm25 4 years ago

Attitude Indicator...For a car....

How would one make a cheap attitude indicator for a jeep...i go offroading and i just thought it would be cool to make my cockpit look more like a cockpit, im putting up some toggle switches and a couple other cool accents but i thought the coolest would be something that shows me how far my jeep is tipping when i flex it.  So if anyone has any crazy ideas on how to pull one off let me know, ive had some ideas of like pinning a floating compass to an axis so it only tips back and forth...but the real electronic ones for aviation are thousands of dollars and very impractical.  Help me out here people....  email me at if you have any ideas

Posted by NathanMenke 6 years ago

what is important about playing the guitar.?

Over the years many young players have said to me "Boy ,I wish I could play like that"   My stock Question is:  Do you enjoy playing.??? of course most say yes.  I would tell them that's the important thing not if you are as good as this or that person.   Each individual has their style, to illustrate, I was ill some years ago and my wife and I went to a concert...Box Car Willie, as the band struck up with a steel guitar I looked at my wife and said "Dave Nutt: and indeed it was when the curtains opened,   You see we all have our own "Personal" style...Forget copying anyone be yourself.  I can't think of a single successful guitarist  who copied someone else here are a couple of examples Chet Atkins, Albert Lee(He has been playing as long as me, currently works for Earnie Ball in the states) and James Burton.    2.Mark Knopfler. 3 Johnny Hiland (Who is Blind) all different ...similar styles with some and yet still different.   So keep pickin' and enjoying.

Posted by fenderphil 7 years ago

Simple crosshair laser level pointer

Is there something or someone here that can tell me how I can make a one or two laser pointer into a crosshair laser level? 90 degrees on all sides

Posted by elkaddalek 1 year ago

CNC auto level

I bought a 3 axis CNC machine from amazon, after putting it together with poor instructions, I had what looks to be a auto level prob wire. I am trying to figure out how and where to connect this single wire to the board? the IC in a atmega328p with Arduino loaded . I have some photos that maybe someone could tell me which pin to connect this to? thanks

Posted by DominickP4 1 year ago

GCSE to A-Level transition

Hello all, I have recently moved up from GCSE level education to A-Level education and I am happy with my subject choices after one week of being back after a long holiday. I am taking: Chemistry Physics Mathematics Design and Technology: Product Design - Materials I am worried about my mathematical ability though. Despite getting an A grade at GCSE, my true ability (in general) is somewhere around a B. I excel in geometry, shape, mechanics - anything with REAL WORLD application. I do not fare so well in the 'Maths for the sake of Maths' bits, namely some algebraic sections and whatnot.  I am aware that the jump from GCSE to A-Level is a difficult one and that many students struggle with it (Maths in particular). I just thought that I would post this here to see if anybody who has been through a difficult 'step-up' in work difficulty could offer me some advice.  Also, this is a forum post so that anyone, in any education system, in any 'step-up' can discuss their issues, or offer their advice. So, don't feel left out Yanks! :-) I thank you all in advance.

Posted by DELETED_zoltzerino 7 years ago


So I looked up the data for the LM3914 followed the steps and I still cant get this thing to work I tried it two ways. I want to be able to set this up for variances of voltage say from 1.5V to 30 volts. Any advise would be great.

Posted by dominick.j.pezza 2 years ago


I've got a 2 channel color organ with an electret mic for input. I'd like to be able to remove the mic and run it directly from one side of a stereo output from a cd player. I know I need to have something there to replace the mic, but I'm an audioidiot. Thanks. BTW, this is for a puking skeleton for Halloween. The color organ will drive the pump, while the audio will be, well, the audio.

Posted by oobadooba 9 years ago

Simple question about RAID 1 setup

I plan on buying 2 of the following Hard Drives: I also buy the following RAID controller: Will these be compatable with eachother in a RAID 1 setup? After plugging the HDDs into the controller, and the controller into my MB( is there anything else I need to? Or will BIOS automatically take care of it? Thanks!

Posted by metrogdor22 7 years ago

Leveling a tree stump

Hi there everyone. So I have a bit of a dilemma. There's 3 or 4 beautiful knotted and dried tree stumps that I pass everyday and I've finally decided I want to drag them back home with me (which is another problem entirely) and use at least one to give my rain barrel some height. It's about a foot and a half in height, and just about thick enough to handle it. My problem is that the top is completely uneven and has been hacked with a chainsaw. I'd need to level the whole thing on top and bottom to make it useable. I just have no idea how I can go about doing this WITHOUT using a chainsaw. Thanks in advance everyone. I'll post photos soonish.

Posted by norwish 5 years ago

Low battery indicator

Can someone please provide me with a schematic to turn on an LED when a 9v PP3 gets low (~<20%), no microcontrollers, the simpler the better. I am hoping you can do this with a few diodes, transistors, resistors, and maybe some capacitors, but I can't think how this would work.

Posted by andy70707 7 years ago

I need to be able to see the charge level of a 6v rechargeable battery and want it to be as simple as possible?

I need to be able to see the charge level of a 6v rechargeable battery and want it to be as simple as possible?

Asked by HariK38 1 year ago

Simple battery charge level indicator? Answered

I need to be able to see the charge level of a 12v rechargeable battery and want it to be as simple as possible. Would this setup work: 3 zener diodes (at different breakdown voltages 10, 11 and 12 volts for example) with cathodes connected to positive so that when the battery was above their breakdown voltage an led could light up. Here is a diagram:

Asked by Scytheon3 6 years ago

Whould boiling lemon juice effect the ph level of the citric acid? Answered

And is there any way I could remove the sucrose? I want to as close to pure citric acid in the lemons.

Asked by 9 years ago

Any good software to image A drive?

I need to: Low level, Image a 3GB drive with BeOS installed on it, with, Of course, BeFS. Some programs don't work, as the unknown filesystem does not register a drive in windows, and they seem to be too high level. I want to completely image a drive, connected to my laptop via a USB HDD reading thingy, The boot sector, all the files, and everything. Any suggestions to good(free) software that can easily low level image a drive? Thanks ~ReCreate

Asked by ReCreate 8 years ago

Advanced Level? Answered

What should we do to take advanced level lessons

Asked by Learner_1981 1 year ago

Adjusting pH levels?

So, I am doing a science fair project about what  pH level is best for sea monkeys and what happens with the other levels.  Dies anyone know how to  adjust the pH levels easily in such a small amount of water??

Asked by kyluddy 4 years ago

I am trying to automate a hydroponics system with many sensors and realys. Has any one done this before?

Sensors: Air Temp Water Temp Humidity Air Flow Light Levels Water Depth Ph Levels Co2 Levels in the Air Co2 Levels in the water Oxygen Levels Air Oxygen Levels Water

Asked by ckirchner001 5 years ago

How do I level out the garden?

Hello, could someone please tell me how I would go about levelling out my garden or particular blocks of it? Thank you in advance.

Posted by ShaunHill 9 years ago

Is Auto Levelling Important?

Hi, I am new to 3D printing and would like to purchase a 3D printer yet I do not know exactly what Auto levelling does and if I should purchase a 3D printer with Auto levelling or not, Thankyou for your time and assistance.

Asked by Taha2002 1 year ago

Help With Warcraft III World Editor

I have recently been creating a tower defense map with the warcraft world editor and I am just starting to make all the waves. My map is a Solo TD where the creeps move through multiple checkpoints. The problem I'm having is that if a creep manages to step into a region that he is supposed to later on (if someone mazes and makes it so they have to go through the last region before the first) then the creep dies. I was wondering if there is a way to make it so they HAVE to enter the first regions before the others apply to them. There is a way to do it with variables but that way is going to take me FOREVER. I was wondering if there is a faster way than just creating a load of variables so when a unit walks into a region it records it and after a certain number the next region is activated. That way also has a few flaws that would be difficult to maneuver around. Thanks in advance! The red words in the picture say "makes them go that way". It did't show up as well in JPEG form.

Asked by noobererer 8 years ago

Circuit Diagram Experts Needed. Thanks. Answered

Hi, (I posted an image)I found this circuit in an book of mine because I wanted to build a VU meter. I only want to simplify this circuit. I don't need sound coming out of the VU meter; so I could have just remove the speaker and be done with it. But... is there anything else in the diagram that is only related to the speaker in which I could remove? All I need from this circuit is the led reacting to the audio input like a VU meter. Eliminating unnecessary parts will help me make it smaller. Thanks! Helpful things to know about diagram: Ignore R1, C5, U2.... those are just references to another diagram. 324 is an Operation Amplifier IC (there is only 1)546 is an Audio Power Amplifier IC (there is only 1)the Si is a silicon diodethe VR is a 50k ohm control volume (potentiometer?)6 volts going inIgnore the funny looking earphone, thats the audio input instead.I posted one General Image and 4 close up Images. Any other question about the diagram feel free to ask.Once Again Thank you for helping a newbie.

Asked by Dmxspider 8 years ago

Will there be an advanced level class? Answered

Question Body: give us more detail on your question...

Asked by prinak 1 year ago

how do I level a ceiling fan?

OK, I've played with those @%!%^ weights till I'm dizzzy - how do I level this dumb fan??

Asked by NanaMomsers 7 years ago

Regarding Featuring at various levels...

At the moment, a full feature for a project gets that project onto the front page as an "Editor's Pick", but all a feature at Category or Channel level earns an author is a small star on the project's thumbnail. What I think should happen is... I look at the front page, I see the most recent top-level featured projects (as now) I click on a Category, say, Food, I see all the top-level food projects, plus all the Category-level featured projects. I click on a Channel, say, Sandwiches, I see all the top-level, Category-level and the Channel-level sandwiches. That way, authors will be rewarded for their work with the increased traffic they deserve. The photo is irrelevant, I just don't like publishing topics with no image.  It's the Angel of the North, with Conker-X sitting on the toes.  I took it on the way home from the Newcastle Maker Faire.

Posted by Kiteman 7 years ago

Converting to/from line level signal for guitar effects? Answered

So I've got some effects pedals that don't get along with my Egnater Tweaker's effects loop, namely the HBE Frost Bite Flanger, but my Carbon Copy doesn't do too well either.  I've determined the problem to be the effects loop (which is at line level), and the previously mentioned pedals won't accept line level signals without a significant volume drop and high-end attenuation. So my idea is to convert the line level signal being sent from the effects loop to instrument level, run it though my pedals, and then back up to line level and to the loop's return.  This would do the trick to get it down to the right level, but how do I get it back up to line level?  It's passive so I wouldn't think you could go from -10db to +4db, right? I'm also concerned about introducing noise and tone sucking.  Additionally, the send and return both have a different impedance, would I need to compensate for that? Any ideas on a way to achieve this, or a better method that hasn't occurred to me?  Any help is appreciated.

Asked by RelaxedSoup 7 years ago

What experience level should I have? Answered

This does say it is a beginner course, but what, if any are the prerequisites of this course. Is it truly beginner?

Asked by camerondon 1 year ago

What is line level output? Answered

I saw it in Kaustic Machine's schematic for the Atari Punk Console. Does anybody know what it is?

Asked by blinkyblinky 6 years ago

boom blocks levels

This future instructable will show you how to make levels that I make or if you have made on I will collaborate the future instructable with you and you can post yours. if you don't want to be colaborated all you have to do is post a picture of your level ,tell me what map you used ,what story line you edited it from. and I will re create it and ad it to this instructable. please do not post a level unless it's some awesome machine ,or if it can actually be beaten. ideas for levels: try to get Gorrilda to the Gurts but lure her to explode bombs to blow them up. Try to make here take a detour so she doesn't. I made one just like that where it shoots a Gurt into space if you don't stop Gorrilda from detonating the bomb. more coming soon... maybe.

Posted by the_burrito_master 9 years ago

How should I make a level, mosaic table?

I'm thinking about making a mosaic table from broken ceramic lamps. If I want to fill in the empty space to create a level surface, what should I use? And how long does it take to harden?

Asked by 8 years ago