Need Help!

Replies

• 

  Patryk

  Is there nobody in this huge 83,000 person pool who can help me?
  
  If bumping is not allowed, then I apologize; but my free time is extremely limited and I would love to do this!
• 

  shreyasm89

  Hmmm....Good that you are intersted in electronics even before entering engg.I haven't seen your RadioShack ckt. but your idea of making a simple voltmeter is a great way to start.Before going ahead out of curiosity in what grade are you studying?
• 

  Patryk

  I am currently a senior in high school
• 

  shreyasm89

  So basically you must be studying galvanometer based voltmeters which work on a magnet & a coil?Right?Any exposure to digital voltmeters?
• 

  Patryk

  yeah, my dad has one laying around in the house...i have done a few labs with one aswell
• 

  shreyasm89

  ok...great. Actually here I think the concept of digital voltmeter is not required as your project is simply a battery lavel indicator.t will show you the current remaining power on your DC batteries just as the fuel-guaze works & all.The big block that you see is the IC which takes the i/p from the battery whose level you are measuring.This ckt. is for 15V supply which is normally used in engg. colleges for experiments.I am assuming that you have absolutely no knowhow of reading schematics & will go through each part. The blue triangles that you see are nothing but LEDs which you normally see on every device nowadays to indicate anything. As the level will decrease the no. of LEDs on will decrease and according to the given values on the ckt. diag. you will be able to know what is the voltage level on the battery.The nos. that are mentioned along the lines are the pin nos. of the IC to which the wire is connected.The arrow across the resistance will mean that the value is variable.
  
  Tell me if you have any further doubts.
• 

  dheerajkvs

  It is good to see people interested in these thing. Basically the given circuit (ckt) is about a voltmeter which works with the LED's i.e the LED's glow according to the voltage supplied and as given in ckt diag different LED's are used for different voltages.You also need some resistors and some variable resistances to complete the circuit.hope you know the function of the resistor. If you have a doubt please post.
• 

  Patryk

  is there a way to use an actual number reader, where it gives you exact voltage? I found a led display but only one digit, i would atleast like it to show a fractional quantity
  
  #-Link-Snipped-#
  
  Or do you think the leds are fine for beginners?
  
  also, where would i find this lm3914?
• 

  shreyasm89

  There is way the actual no. can be displayed. & 7-segment LED display is a good way to begin as it is nothing but an array of LEDs arranged in such a way that it will show a display in the form of a digit from 0 to 9. But to understand how this display works you will need an understanding of Digital Logic & K-maps?Ever heard of logic gates?
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  Patryk

  Nope, dont know anything, i guess ill stick with the basics
• 

  Voltaire

  shreyasm89

  ok...great. Actually here I think the concept of digital voltmeter is not required as your project is simply a battery lavel indicator.t will show you the current remaining power on your DC batteries just as the fuel-guaze works & all.The big block that you see is the IC which takes the i/p from the battery whose level you are measuring.This ckt. is for 15V supply which is normally used in engg. colleges for experiments.I am assuming that you have absolutely no knowhow of reading schematics & will go through each part. The blue triangles that you see are nothing but LEDs which you normally see on every device nowadays to indicate anything. As the level will decrease the no. of LEDs on will decrease and according to the given values on the ckt. diag. you will be able to know what is the voltage level on the battery.The nos. that are mentioned along the lines are the pin nos. of the IC to which the wire is connected.The arrow across the resistance will mean that the value is variable.
  
  Tell me if you have any further doubts.

  
• 

  shreyasm89

  I don't know where to start but just remember one thing that we need to convert your analog voltage into a digital value.the IC lm3914 that that you have used is a voltage sensor IC.
• 

  Patryk

  are there any stores that sell this lm3914? I looked at radio shack and they didnt have it.
• 

  shreyasm89

  @patryk- you should first understand the internal working of that IC ckt and then buy it. Check out your neighbourhood electric hardware componenets store. It seems a pretty common IC. You should get it anywhere. And since you have decided to design the cicrcuit now do it on a BREADBOARD. Hope you know what a breadboard is...no offence buddy but just wanted to make sure you are not stuck.
• 

  dheerajkvs

  Hey Buddy im3914 is an ic which is available in any local electronic stores.Try some stores which sell some multimeter and resistors and all others components and if you dont find any ask someone who fixes televisions where e gets his components and try there you will find it. BREADBOARD is like a circuit board in which you test the circuit before fixing on a printed circuit board. It is cheap,I got it for 50 rupees in india which is like a dollar in US and seriously try the circuit on a breadboard and then go for a PCB.Don't put the circuit on PCB directly,if you do so you wont be able to remove it if there is any problem. Use a base for the IC so that you can remove the IC and just solder the base,this saves you money as you dont need to buy the IC again if something goes wrong.