12 Volt Fluorescent inverter for 20 - 40 Watt tubes

Description: This is a low-cost project for 20 or 40 watt fluorescent tubes. However, the most efficient is to use a 40 watt tube (or two 20 watt tubes in series). It's a circuit you can put together from junk box components or build from a kit. It's very simple to build and requires no printed circuit board. The transformer is hand-wound on a ferrite rod (from an old transistor radio), and the winding wire can be salvaged from an old transformer. The ferrite core of the transformer is an antenna rod from an old transistor radio. You could use a slab antenna, but we have chosen a 10mm diameter rod, 8cm long, and the first winding to be wound on it is called the primary. We are purposely keeping costs down to show how cheaply it can be put together. Depending on your stock of parts, the cost could range from $3.00 to about $15.00, and if the wires from the transformer are soldered to the ends of the tube(s), you can create a free-standing light that can be set up in the garden to illuminate a dark area without the fear of running 240v wiring. The cost of powering the circuit is about 22 watts, and this will produce the same light output as a 60 watt globe. With a normal fluoro operating on the 240v mains, a ballast (or choke) is needed in series with the tube to limit the current after the tube has "struck." This ballast dissipates about 10-20 watts for a 20 watt tube and reduces the efficiency of the circuit. If the ballast is replaced with an electronic circuit and high-frequency transformer, the losses are less than 5 watts. Furthermore, if we do not drive the tube as hard as the 240v version, we can get even better efficiency. The size of the tube you will need will depend on the area you wish to illuminate and the battery capacity you have available; however, it is important to realize that the higher wattage tubes offer the greatest efficiency. This is because they have a longer length and larger diameter (than, say, an 8 watt tube) and give more light over a larger area. That's why we have concentrated our design on the 40 watt tube. You can get plenty of circuits and devices that power the 4, 6, and 8 watt tubes, but nothing has been done for the 40 watt variety. There is another range of tubes, commonly called the "compact fluoro" or high-efficiency fluoro. These are a folded fluorescent tube having a rating of either 11 watts, 13 watts, or 18 watts. They are not covered in this project as they are expensive to buy and more difficult to drive. They are actually driven VERY HARD, and if you feel one after it has been turned on for a few minutes, you will find the tube is quite warm. They are not really suitable for indoor use as they take a while to come on and don't give enough illumination for an average room. We have tried the whole range of these tubes and come to the conclusion that they are only suitable for outdoor use as a decorative lamp or for partially illuminating a dark area. This is one of those situations where the old-style product is the best. I think you will find that the glitter of the compact lamp has almost faded by now as the public has come to realize they are not the whiz-bang invention of the century and have not taken over any of the areas already serviced by the tungsten lamp or standard fluoro. After all, you can buy a 100 watt globe for less than $1.00, and a compact lamp costs about $20.00. It will take more than 5 years for the savings in electricity to equal the cheap 100 watt globe. The one problem that lets compact lamps down is the electronic circuitry. The electrolytics in the base are driven very hard and tend to dry out after a few years. We have found lots of discarded bases (with tube) with this problem. Apart from this, the fluorescent lamp has a number of advantages over incandescent lighting. The main one is efficiency. This is due to the fact that it's a cold light, in comparison to incandescent light where the light is produced by the heating of a piece of wire. The other advantage is the light does not come from a point source and thus it is more evenly spread over a larger area. Fluorescent lighting is approximately 400% more efficient than incandescent lighting (50 Lumens/watt compared to 12 Lumens/watt for a 100 watt tungsten lamp), although there are some losses in the ballast. A 20 watt tube (plus 10-20 watts for the ballast) gives the same light output as a 100 watt lamp when it is heavily driven in the 240v mode. For a normal household, the lighting component of the electricity bill is only a fraction of the total and doesn't warrant a house to be converted to fluorescent lighting. But if you are considering setting up a home in a remote area, where mains electricity is not available, you will appreciate the advantage of high-efficiency lighting. With modern electronic circuits, fluorescent lamps can be designed to operate very efficiently, and with this project, you can build the circuit yourself and operate it from a 12v supply.

This project involves constructing a low-cost fluorescent lamp circuit suitable for 20 or 40 watt tubes, emphasizing the use of salvaged components to minimize expenses. The design centers around a hand-wound transformer made from a ferrite rod, typically sourced from an old transistor radio, which serves as the core for the transformer. The primary winding is to be placed first, ensuring correct orientation and functionality. The circuit is designed to power the fluorescent tubes efficiently, requiring no printed circuit board, making it accessible for hobbyists or those with limited resources.

The project highlights the advantages of using a 40 watt fluorescent tube or two 20 watt tubes in series, as they provide better light output and efficiency compared to lower wattage alternatives. The estimated cost of materials ranges from $3.00 to $15.00, making it an attractive option for outdoor lighting solutions where traditional 240V wiring poses safety risks. The circuit operates at approximately 22 watts, yielding a light output comparable to a 60 watt incandescent bulb, thus demonstrating significant efficiency gains.

A critical aspect of this design is the replacement of traditional ballasts with an electronic circuit and high-frequency transformer, which reduces power losses to less than 5 watts. This modification not only enhances efficiency but also allows for lower operating temperatures, further extending the lifespan of the components involved. The choice of fluorescent tubes is crucial, as higher wattage tubes are more efficient due to their size and light distribution capabilities.

This project serves as a practical solution for individuals in remote areas lacking access to mains electricity, providing a means to create effective lighting using readily available materials. The incorporation of modern electronic circuit design principles ensures that the fluorescent lamps can be operated efficiently from a 12V supply, making this project a valuable resource for DIY enthusiasts and those interested in sustainable lighting solutions.This is a low-cost project for 20 or 40 watt fluorescent tubes. However the most efficient is to use a 40 watt tube (or two 20 watt tubes in series). It's a circuit you can put together from junk box components or build from a kit. It's very simple to build and requires no printed circuit board. The transformer is hand-wound on a ferrite rod (from an old transistor radio) and the winding wire can be salvaged from an old transformer. The ferrite core of the transformer is an antenna rod from an old transistor radio. You could use a slab antenna but we have chosen a 10mm diameter rod, 8cm long and the first winding to be wound on it is called the primary.

We are purposely keeping costs down to show how cheaply it can be put together. Depending on your stock of parts, the cost could range from $3.00 to about $15.00 and if the wires from the transformer are soldered to the ends of the tube(s), you can create a free-standing light that can be set-up in the garden to illuminate a dark area without the fear of running 240v wiring. The cost of powering the circuit is about 22 watts and this will produce the same light output as a 60 watt globe.

With a normal fluoro operating on the 240v mains, a ballast (or choke) is needed in series with the tube to limit the current after the tube has "struck". This ballast dissipates about 10-20 watts for a 20 watt tube and reduces the efficiency of the circuit.

If the ballast is replaced with an electronic circuit and high-frequency transformer, the losses are less than 5 watts. Furthermore, if we do not drive the tube as hard as the 240v version we can get even better efficiency.

The size of tube, you will need, will depend on the area you wish to illuminate and the battery capacity you have available, however it is important to realise that the higher wattage tubes offer the greatest efficiency. This is because they have a longer length and larger diameter (than say an 8 watt tube) and give more light over a larger area.

That's why we have concentrated our design on the 40 watt tube. You can get plenty of circuits and devices that power the 4, 6 and 8 watt tubes but nothing has been done for the 40 watt variety. There is another range of tubes, commonly called the "compact fluoro" or high efficiency fluoro. These are a folded fluorescent tube having a rating of either 11 watts, 13watts or 18watts. They are not covered in this project as they are expensive to boy and more difficult to drive. They are actually driven VERY HARD and if you feel one after it has been turned on for a few minutes you will find the tube is quite warm.

They are not really suitable for indoor use as they take a while to come on and don't give enough illumination for an average room. We have tried the whole range of these tubes and come to the conclusion that they are only suitable for outdoor use as a decorative lamp or for partially illuminating a dark area.

This is one of those situations where the old-style product is the best. I think you will find that the glitter of the compact lamp has almost faded by now as the public has come to realise they are not the whiz bang invention of the century and have not taken over any of the areas already serviced by the tungsten lamp or standard fluoro. After all, you can buy a 100watt globe for less than $1.00 and a compact lamp costs about $20.00. It will take more than 5 years for the savings in electricity to equal the cheap 100 watt globe. The one problem that lets compact lamps down is the electronic circuitry. The electrolytics in the base are driven very hard and tend to dry out after a few years. We have found lots of discarded bases (with tube) with this problem. Apart from this, the fluorescent lamp has a number of advantages over incandescent lighting. The main one is efficiency. This is due to the fact that it's a cold light, in comparison to incandescent light where the light is produced by the heating of a piece of wire.

The other advantage is the light does not come from a point source and thus it is more-evenly spread over a larger area. Fluorescent lighting is approximately 400% more efficient than incandescent lighting (50 Lumens/watt compared to 12 Lumens/watt for a 100 watt tungsten lamp), although there are some losses in the ballast.

A 20 watt tube (plus 10-20 watts for the ballast) gives the same light output as a 100 watt lamp, when it is heavily driven in the 240v mode. For a normal household, the lighting component of the electricity bill is only a fraction of the total and doesn't warrant a house to be converted to fluorescent lighting.

But if you are considering setting up a home in a remote area, where mains electricity is not available, you will appreciate the advantage of high-efficiency lighting. With modern electronic circuits, fluorescent lamps can be designed to operate very efficiently and with this project you can build the circuit yourself and operate it from a 12v supply.