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12V fluorescent tube inverter 4 - 65W with high efficiency

     I created this Fluorescent Inverter 12V with goal - reaching the maximum efficiency. I constructed it as a push-pull inverter with MOSFETs. They are driven from circuit IR2153. This ic is originally designed for excitation of the halfbridge, but it can also be used in push-pull topology. The advantage of the circuit is that it has 2 outputs appropriate for excitation mosfets and deadtime 1.2 us. It's a much better solution than the circuit with 555 or 556. Working frequency is 35kHz (ideal frequency for RF excitation of fluorescent lamps). Circuit IR2153 has UVL, ie it wont run at a voltage less than 9V and protects the battery from damage.
     Inverter can power almost any lamp. Power (ie the current) is set by L1. The C1 should also be selected according to the tube. For thin fluorescent lamps (T5 size, diameter 16mm, 4 - 21W) and Small fluorescent DZ (U-shape or 2U, 5 - 18W, without integral starter - 4-pin) can be used capacitor and choke from almost any energy saving lamps (CFL). Value of starter capacitor is about 2n2 to 3n3. The tubes from compact fluorescent lamps can be directly connected to this inverter with their original HF ballast and starting capacitor. Output voltage and frequency corresponds to the ones from the compact fluorescent tube inverters (rectangular waveform at approximately 160V 35kHz). For bigger fluorescent lamps (T8 26 mm or 38 mm and large T12 fluorescent DZ, 15 - 65W, 0.43 A) you must use coil with appropriate inductance and sufficiently dimensioned, or combine 2 to 3 chokes from CFLs in parallel. For large fluorescent lamps the rated current is from 0.38 to 0.43 A. The current through fluorescent lamp can be fine-tuned by changing the inductance of the coil (change of the air gap) or a small change in operating frequency. Change is possible in the range of about 30 - 40 kHz and is conducted by changing the value of components in the oscillator (330p, 68k). Start capacitor is chosen to be close to resonance with the choke. After switching there is increased voltage around 500V produced by the series resonance, it strikes the lamp. C1 must be rated to 1000V. Due to the high efficiency, the power into fluorescent lamps can be accurately estimated by the power drawn from the source of 12V. The converter can also drive more lamps in parallel. Each then has its own capacitor and inductor.
     The transformer has core without air gap. Used wire diameter must be rated according to the desired output power. With small fluorescent lamps it is better to use transistors IRFZ44 and a core with a smaller cross section. Then he must increase the number of turns. Eg. if you use a core with cross section. 45mm2 instead recommended core 90mm2, increase the number of turns of windings twice, ie 2x10 turns and 132 turns. The advantage of a smaller transformer less load current. Then a small lamp inverter is as effective as inverter for large lamp.
     Transistors IRF3205 (55V 110A rON=0,008R max; td(ON)=14ns, tr=101ns, td(OFF)=50ns, tf=65ns, CGS=3250pF) don't need heatsink for lower powers. Efficiency of this inverter is more than 90%.

     Warning! although the circuit supplied from a safe voltage 12V, the output has life-threatening voltage up to 500V, or even more! All parts of the secondary side (in the diagram to the right of the transformer) including fluorescent lamps must be protected against accidental contact.

The schematic of fluorescent tube inverter powered from 12V.
The schematic of fluorescent tube inverter powered from 12V.

Experimental construction of fluorescent tube inverter
Experimental construction of fluorescent tube inverter

Inverter powers up a 36W fluorescent tube PL-L 36W/840 PHILIPS (DZ) with luminous flux 2850lm
Inverter powers up a 36W fluorescent tube PL-L 36W/840 PHILIPS (DZ) with luminous flux 2850lm (light efficiency 80lm/W). C1 = 10n 1kV, C2 = 220n 250Vac.

Homemade fluorescent tube inverter II. with 8W F8 T5 tube
Homemade fluorescent tube inverter II. with 8W F8T5 tube (16 x 300mm). C1 = 2n2 1kV. C2 = 100n 250Vac.

Working homemade fluorescent tube inverter
Working homemade fluorescent tube inverter with rechargeable sealed lead-acid battery.



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