rabid_zuchinni Posted May 13, 2006 Report Share Posted May 13, 2006 erm...excuse my ineptitude...but I was looking at the plans for the "Simple but reliable car battery tester" and I noticed it talks about adjusting sensitivity and offset. What are these things and how do I adjust them?http://www.electronics-lab.com/projects/automotive/009/index.html Quote Link to comment Share on other sites More sharing options...
helio905 Posted May 24, 2006 Report Share Posted May 24, 2006 If you are simply going to test 12vdc I would stick with a volt meter from justabout any store. Amp and volt will Very with a car elect. system. Most of the timeit is ether hot or not. Quote Link to comment Share on other sites More sharing options...
MP Posted May 30, 2006 Report Share Posted May 30, 2006 I recommend that you just go with the settings in the project. It sets the first LED for 8 volts and sensitivity of the circuit. The LM3914 data sheet will help you understand this better.MP Quote Link to comment Share on other sites More sharing options...
fjqing8888 Posted June 20, 2006 Report Share Posted June 20, 2006 This one can only get the float voltage of the battery. If you really want to make a perfect tester you should make a tester which can get the capacity for the battery. Quote Link to comment Share on other sites More sharing options...
MP Posted June 20, 2006 Report Share Posted June 20, 2006 What would be the point? This one is no different than the voltmeters in the dash of cars. When you suggest that someone scrap their project, you should post the replacement that you are suggesting. Thus, a comparison can be made.MP Quote Link to comment Share on other sites More sharing options...
ante Posted June 21, 2006 Report Share Posted June 21, 2006 It is wrong to call this project a “Simple but reliable car battery tester” this project is not a battery tester! It is a voltage measuring device which reveals nothing about the batterys condition just its voltage! Quote Link to comment Share on other sites More sharing options...
fjqing8888 Posted June 22, 2006 Report Share Posted June 22, 2006 Yes! Just my point! I agree with Ante's opinion.A real battery tester should be to get the capacity for the battery. Should not just be a volt. meter.Feng Quote Link to comment Share on other sites More sharing options...
MP Posted June 22, 2006 Report Share Posted June 22, 2006 It says in the text of the project that it is a voltage monitor. I don't see anywhere in this topic where rabid wants anything more than that.If you are offering him an alternative....post it.MP Quote Link to comment Share on other sites More sharing options...
audioguru Posted June 22, 2006 Report Share Posted June 22, 2006 The schematic calls the circuit "a level monitor". ;D Hee, hee. Maybe it shows how straight and level is the battery. Maybe it also shows if the battery is nearly dry. Hee, hee. ;D Quote Link to comment Share on other sites More sharing options...
ante Posted June 22, 2006 Report Share Posted June 22, 2006 Hi MP,Rabid says: “looking at the plans for the “"Simple but reliable car battery tester"”!I just wanted to make sure he didn’t think this circuit works like one! Quote Link to comment Share on other sites More sharing options...
MP Posted June 23, 2006 Report Share Posted June 23, 2006 Well, I guess he did mention something about ineptitude... ;DMP Quote Link to comment Share on other sites More sharing options...
saltapidas Posted April 29, 2007 Report Share Posted April 29, 2007 hello, I am new in the forum and new with electronics also.I am trying to built this circuit but I wonna display a range between 11 and 14.4 volts.I would be grateful if someone could describe how lm3914 works and furthermore help me calculate the resistor values for this range.I already have download the datasheet http://www.national.com/ds.cgi/LM/LM3914.pdfand a sample circuit http://www.national.com/an/LB/LB-48.pdf but with my limited knowledge on electronics were not that helpful. Quote Link to comment Share on other sites More sharing options...
MP Posted April 30, 2007 Report Share Posted April 30, 2007 Look at the schematic in the data sheet. R Hi and R Lo determine the end points. As you can see, the chip is based on a series of comparators.MP Quote Link to comment Share on other sites More sharing options...
saltapidas Posted April 30, 2007 Report Share Posted April 30, 2007 R Hi and R Lo determine the end points. MPthanks for replying. what resistor values should I use to display a range between 11 and 14.4 volts Quote Link to comment Share on other sites More sharing options...
MP Posted April 30, 2007 Report Share Posted April 30, 2007 You need to read up on how comparators work. Breadboard this chip and get out your calculator. Then this can be a learning experience for you. You will be surprised at how easy it is once you get into it.MP Quote Link to comment Share on other sites More sharing options...
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