40W Fluorescent Lamp Inverter

By Bart Milne

This 40W fluorescent lamp inverter allows you to run, 1 40W fluorescent tube or, 2 20W fluorescent tubes, from any 12V source capable of delivering 3A. This is basically a larger version of the 12VDC Fluorescent Lamp Driver and can be used to light regular or blacklight tubes.

Schematic

Parts:

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Winding L1 and T1 Wind L1/T1. You will need a piece of AM antenna rod that is about 6-10cm (2 1/2 - 4 inches) long to wind T1/L1 on. T1/L1 are wound on the same core. Put a layer of heatshrink between each layer of wire and over the ferrite core itself to insulate it. Leave at least 5cm of wire at each end of the coils.

Primary Coil: Wind 60 turns of 1mm diameter enamelled copper wire on the first layer and put a layer of heatshrink over it. Feedback Coil: Wind 13 turns of 0.4mm enamelled copper wire on the core and then heatshrink over that.

Secondary Coil: This coil has 450 turns of 0.4mm enamelled copper wire in three layers. Wind one layer and then heatshrink over it. Do the same for the next two.

When you first turn it on...

For the circuit to work properly L1 must be connected the 'right way' around. To do this connect the 2.2 Ohm 1W resistor (R3) in series with the positive supply. Connect a 40W fluorescent tube to the high voltage winding of the transformer. Momentarily connect power. If the tube doesn't light immediately reverse the connections of L1. If the tube still doesn't work, check all connections. When you get the tube to light remove the 2.2 ohm resistor and the circuit is ready for use. You will not need R3 again.

Notes 1. This circuit is designed for 230/240V lamps, although 115V units should work as well.

2. This page has been extensively rewritten again by Bart Milne. (8^th September 2002), including an update to the circuit diagram.
My email address is bjmilne@lycos.com . Please email me back to say if you found this page helpful.

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