If, like me, you have a camera, you certainely also have some batteries,
the issue is, you never know if a battery is full or empty !
so I made a portable module on a battery cap, in order to give me a rough idea of the power left.
Step 1: Material
For this project you will need:
- a battery cap
- LM3914 IC
- 10 led (I only used 6)
- resistors (4.7K, 56K, 18K)
- 10K potentiometer (for the test)
- hot glue gun
- soldering iron
Step 2: Prototyping
I found a schematic with the LM3914 giving the level of a 12V battery so I made it on a breadboard,
personally I have a canon camera, batteries are 7.4V so I wondered if this gonna work ...
On my breadboard I tested a charged battery and adjusted with the potentiometer to light the first LED (pin 10)
then I tested a discharged one, and notice that the 6th LED lit (pin 15).
So the circuit works but I wanted the discharged battery to lit the last LED so I simply remove the four others LED,
then, remove the potentiometer, measure the resistance between each of is pin and replace it with two resistors.
For me, it works when it's completely on the right so I replace it with: a 10K ohm and a wire (as shown on the second schematic
It's now time to solder that together
Step 3: Mounting
First, let's connect all the (+) of the 6 LED and glue this chain on the battery cap.
The connections with the battery are made by wires passing through the plastic cap at the spots of the connectors of the battery.
Then I soldered the four resistors around the IC and I made all the connections between IC and LED's;
At this stade, the module should work!
Step 4: Possible Improvements
You can personnalise your module,
For exemple you could pour epoxy resin all around the circuit to make it strong and waterproof.
You also can put a little switch between pin 9 of the IC and the (+) in order to change the display mode.
I hope you liked this project!