Note and precautions: CFL's contain mercury which is hazardous material, so it should be handled accordingly
Most CFL lamps, electronic circuits are working perfect and are still useable, only the bulb goes defective. CFL circuit of 18-24 Watts are useful for the activation ofreplacement type two feet 18-20 Watt Florescent Tube Light bulb.
Step 1: Find a CFL
You will need a CFL as shown in picture. Any CFL of which bulb is defective, broken or has outlive its life is useful for this modification. Drive voltage may be according to your country 110 Volt or 220 Volts. In my country (Pakistan) voltage standard is 220/230 Volts.
Step 2: Disassemble
Disassemble the CFL as shown in the picture. Note there is a single pair of wires/connections which goes to the 110/220 Volts. other side has two pair of wires 9four wires) these will be connected to the replacement type 20 Watt 24" Florescent Light bulb. After disassembling you will need electronic module from it. Check carefully there are no burnt parts on it. Using multimeter check its diodes, fuse etc. some time fuse is found melted you can replace it or bridge with a very thin copper wire.
NOTE;- DO IT IF YOU HAVE ENOUGH ELECTRIC/ELECTRONICS EXPERIENCE
Step 3: Parts required
You will need a replacement type Florescent Light bulb of 18 or 20 Watts type and hardware to hold the tube bulb and ofcourse salvaged electronic module from the CFL.
Step 4: CFL module wiring
Rewire appropriate length of wires as shown, say about 4 to 6 inches.
Step 5: Mounting and Assembling
mount the parts and assemble. Note the CFL module shold be mounted on an insulated plate. I used a piece of Plexiglas and fixed the CFL module with a hot glue on it. For extending connections, use terminal blocks.
Step 6: Connect to light up
Now after assembling check all connections taking care there should be no loose connection. Now power up!!!. I have assembled three such units successfully.