Introduction: 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!

Step 1: 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.

Step 2: Component List

100uf Electrolytic Capacitor 16V C1,C2 -2
100Ohms Resistor 1/4W R1,R2 -2
1N5817 Schotkey Diode 1A D1- 1
150UH Radial Power Inductor 1A IND1- 1
LT1073CN8-12 IC DIP Package IC1 -1
IC Base 8 PIN -1
PCB to Wire Connector- 2
4AA Battery Holder- 1


The input is around 5V and the output is 12V @ 130mA. I used 12V LED spotlight from Futurlec. There are many types of LED Spotlights (MR16) with different number of LEDs. Before buy a one makes sure that the current rating is less than 130mA. Our power supply can deliver maximum 130mA. These are the ratings of MR16 LED spotlight:

Operating Hours: 20,000 hours
Operating Voltage: 12V
Intensity: 55,000 mcd
Forward Current: 80 mA @ 12Vdc
Viewing Angle: 30 Degrees

Absolute Maximum Ratings:
Operating Voltage(V): 14 V
Operating Temperature (Topr): -25oC to +85oC
Storage Temperature (Ts): -35oC to +100oC

You can use this spotlight as an emergency light source.

Step 4: Please Read...

This instructable is under construction.


scottinnh (author)2011-11-18

See 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.

takboilaw (author)2011-09-09

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.

celalboz (author)2011-02-14

circuit diagram is not here..thanks

pavolmaria (author)2010-09-29

Hello, can you publish schematic of this device?