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The CFL Camplight Bug

What can you do with a tennisracket bugzapper and a CFL bulb?

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About this project

And now to something completly different

There are some nice LED-lamps available for your camping trip.
But what's the fun in that?

Wouldn't it be nice to have the light from a warm-white CFL bulb instead? And without having to carry around a car battery?

This one runs a 5 watt CFL from a single D-size 1.5v battery for over 200 hours.

The Bugzapper

The CFL bulb requires more than 400 volts to ignite.
How are we going to get that from a 1.5v battery?

The answer is a tennis racket bugzapper.

They use a small oscillator running at 3 volts with a high voltage transformer to charge a capacitor to approximately 2000 volts.

The stringnet in the zapper is connected to each side of the capacitor and when a bug completes the circuit... ouch!

The circuitboard

If this sounds dangerous, well it's not.

We are going to use only the circuitboard from the zapper.
And we are going to remove the capacitor and voltage stepup on the high voltage side.

And we are going to run it at only 1.5 volts.

What is remaning is about 500v AC to the bulb.
if you touch it you won't feel a thing since it doesn't contain any current. But it has enough to strike our CFL.

Modify it

Open the bug zapper and cut the 2 wires going to the stringnet.

Before cutting the wires going to the battery, take a note on which goes to plus and minus.

If you feed it power in reverse the transistor in the oscillator will burn out.

Desolder or cut away all the components on the high voltage side.
That's the side with the large green capacitor, a resistor and a diode.

You should only have 2 wires from the transformer at the output.
And all of the components on the side with the LED and transistor.

Modify the bulb

The bulb won't light by connecting to it's ordinary screw base terminal so it has to be modified.

Pry the base open. It is glued at 3 or 4 points.

You may have to use a saw or dremmel but be careful not to break the glass tube.

They contain mercury so if you happen to break it, open a window for 20 minutes and leave the room before cleaning up the pieces.

Inside is a board with 4 wires going to the tube. 2 wires to each end.

We don't need the circuit board so cut these 4 wires as close to the board as possible.

Now join the 2 wires from one end of the tube by twisting them together. Do the same with the 2 wires from the other end of the tube.

You should now have only 1 wire from each end of the tube.

Putting it together

Solder the 2 wires from the bulb to the 2 pins on the transformer in the zapper.
I added some insulation to the bare wires so they won't short anything out.
I also replaced the 2 green wires originally going to the battery with a red and black wire.
Connect it up to a 1.5v battery and voila, the bulb should light.
You now have a CFL camping light that runs on a 1.5v battery.
Once it works the LED on the circuitboard can be cut away.
It just draws unnecessary power from the battery.
Besides camping it also makes a great garden or cabin light.
Just add a nice cover and a power switch.
I used a warm-white bulb because it looks nicer in a tent.
You'll have a much brighter light with a cool-white bulb.
It also works with ordinary FL-tubes up to 18 watt size.

The CFL Bug

Make a serve with this?

Salvage the high voltage board

The CFL bulb




Jan Ostman
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Published on

January 20, 2014
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