Introduction: LM 3914 Battery Level Indecator
The LM3914 is a simple piece of IC.. ( not going to lie it was rough at first) this is because I had no Digital DC Power Supply That way I can reference my voltage. I have tried with a 9v battery and it was very frustrating. But all in all the DC Power Supply helped a lot. This also helped me set my 10K Potentiometer.
Here we go
NOW the second pic is the DC source this is where you will set your desired Voltage be sure not to over expose the IC too much volts
Step 1: Things You Need!!
Here I have assorted jumpers.
here is a 10nf capacitor, and a 50v 3.3uf CAP
Resistors 1 (Green ,Brown, Red, Gold 5.02K) and Resistor 2 ( Brown, Black, Gold, Gold 1.3k)
Step 2: LM3914 IC and LED Bargraph
1. LM3914 is a IC that can control LED in Bar graph or dot mode (also you can use single LED's) HERE is where you can find the data
2. The Bar Graph is very common in a lot of different models for what I Do I have one on the M777A2 Howitzer to tell us our battery life, also a digital reading on our display.
Step 3: The Process
Here you have the power Strip of the bread board POS and NEG the 50v make sure that the polarity is right, then next the 10nF. Your 10K POT an go on the other side of the bread board.
The white Jumper is PIN 1 this is to the lowest value LED.
Step 4: All Most Electrifed
With the establishment of Pin 1 to the Lowest led.
We have Pin 2-7 AND 9
- Pin 2 is your Negative or Ground. connect it to ground
- Pin 3 is your Positive. Connect to Positive terminal
- Pin 4 is YOUR Divider Low connect pin 4 with a resistor to the ground
- Pin 5 is your Signal output connect pin 5 with a jumper to the front of the 10k POT
- Pin 6 and Pin 7 are connected together with a 1.3k Resistor this controls your LED brightness Put a resistor across them
- Pin 9 is Mode for DOT/Bar for dot leave it open meaning do not connect to a positive terminal and Bar well you guessed it plug it into the positive terminal.
Step 5: Its's Alive
The remaining Pin 8
Connect 8 to Ground
The 10K POT Connect the blue and white wire as follows. Blue Ground and White Positive.
Also that far right wire is to connect the one positive rail to the other rail where the positive terminals resides for the LED's .
Plug your power source in and watch it light up. Now its a good thing to know what your batteries maximum charge level is that way you can set your 10K to it
Now this does not work with all voltage just cause the resistors I am using is for a 9.7v battery that's where mine tops off at.
Step 6: Finished Product
Although lot of PCB I went through 5 this is the 6th one. Also I just want to update that where my push button is suppose to be, didn't have one so I just connected the terminals back together.
It's finally a success, my first PCB that I made took a lot of time, but its done.
This one here, the LED bar graph I put in back words instead of from Red(L) to Green(R) its opposite. No worries though just batter care and attention to what I am doing. Well I hoped you all enjoyed this
Eagle cad is what I used to set this PCB up
7 years ago on Introduction
This is so cool! I think that I will try this when I have some time!