Instructables

4AA Battery Powered 12V LED Spotlight - 12V Power Supply

Most of the electronic projects and electronic devices are required 12V power source; typically a 12V sealed lead acid battery or AC powered power supply. These are typically large, heavy, difficult to handle, and expensive; portability is less. The best solution is to use a DC-DC Step up converter. These types of convertors are inexpensive, light weight and easy to use. Also provides power management and easy to work with renewable energy sources.

The input power source could be rechargeable AA batteries. Let’s make an environment friendly 12V/130mA power supply!

 
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Step 1: Design the Prototype

Picture of Design the Prototype
The heart of this application is LT1073 IC. It is a power management IC which steps up low voltage into high voltage by switching.

First I etched four PCBs for the prototype using a PCB design software and some other tools. The PCBs are very small (4cmX2cm) because components need to be solder as close as to the IC; because of the performance issues. I made ground copper track as wide as possible.

Now my prototype works fine and I decided to make the PCB in large quantity. I did some changes and sent my PCB file to a local PCB production company and first I got 100 pieces of PCBs. The PCBs are in good quality with solder spots and copper shield; easy to solder.
scottinnh2 years ago
See http://cds.linear.com/docs/Datasheet/1073fa.pdf for a very similar schematic. You should have no trouble with drawing his schematic based on their template, or you can build the reference design in the datasheet.

Also, don't need to simply look for 12V lights that use under 130ma.... you can also get any old 12V LED or incandescent and use resistors to keep power draw down to within levels of the LT chip's spec. So if you have a 150ma LED light, you can get the power draw down to ~100ma using an 80R (ohm) resistor. A chip like this may be rated to 130ma, but that's under ideal conditions and temperature... when it gets hot, it's not 130ma-capable anymore. Datasheets can seem to conflict in some respects.

Although this chip will produce 12v, from a single AA cell there is NO WAY you will get 130ma 12V. Wire up 4 or even 6 AA's in parallel. The fewer parallel cells you use, the more likely the batteries will get very hot because you will be pulling a lot of juice from them. Use your judgement and don't leave this running unattended unless you know what you are doing.

takboilaw2 years ago
please upload the circuit diagram/schematics where do we put input voltage the 4 x AA and the output the proto type does not specify. does the LED already have resistor or do we have to modify them. With this DC-Dc converter how long does this battery last how namy hours. It would be nice to use during brown out or your in dark place.
celalboz3 years ago
circuit diagram is not here..thanks
pavolmaria3 years ago
Hello, can you publish schematic of this device?