Project: Fluoro Lamp Power Inverter (12v)

stanleycarl2 said:

Hello,
how are u doing today?iam stanley from Nigeria.iam a student,i need ur help.I was told in school to present a project topic for my final year.I need ur help ok.
my email address is stanleycarl2@yahoo.com
i will like us to communicate via my email address cos i have time checking it everyday.
thankz
stanley

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First this guy revives a year old thread with rubbish, then the next guy comes in two months later......next thing you know...A fine tale of two newbs triggering a frenzy over an old thread is all but written in the history books.
I have begun to profile different threads. The first thing I do when I see a thread with more than 600 views is check the dates. If you see a thread with like 6 replies and 1500 views it seems to almost always be revived.
EDIT: In this case 19 replies and 2023 views LMAO

Anywaym powering a fluorescent tub is a very common request, and it' easy to do but harder to do properly. If you have any more questions then I can point you in the right direction. Really the only hard part is the transformer which can be a bit experimental but it's not too bad really.

Its more efficent to go and buy a CCL for computer modding. You can get em cheap for 2 bucks at SVC when they have deals. All things for computers work for 12V, all you would have to do it modify the connector.

**broken link removed**
White, they go for 6 bucks.

They won't power standard fluorescent tubes though but I see what you mean, the idea is to use the CCL instead.

Hero999 said:

They won't power standard fluorescent tubes though but I see what you mean, the idea is to use the CCL instead.

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Right, The whole thing comes with an Inverter. But still it does make a good HV circuit, and they do produce nice arcs

Hero999 said:

Flourescent are more efficient than LEDs, well for producing white light anyway.

The problem with this circuit it it drives the tube of pulsed DC not AC so it won't be as birght and it won't last as long. You need a push-pull driver and centre tapped transformer primary to get an AC output and drive the lamp properly.

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This is true about the differance of driving flourescents withpulsed d.c bias . It is also an apparently complex and overkill cicuit for the application which could be =effectivly implimented with 2 transistors driving a center tapped transformer with one hihg volt secondary and one intermediate winding to alternatly toggle the bases / gates . this scheme can be point to point wired withuot any p.c. board . Oh yea ,I forgot that you need 2 bias resistors and 1 capacitor.

That's exactly what I was talking about.
https://www.repairfaq.org/sam/samschem.htm#schmp1

Built this one but I can't get it to work somebody please help.

Have you tried swapping the base connections to the transistors?

Nice oscilator section

Hi hsab...nice tricky oscillator but is this circuit is reliable?

The circuit is quite reliable when properly designed and built. This sort of circuit has been used to power fluorescent lamps of DC power in busses, trains and military vehicles for years without any problems.

Hero999 said:

The problem with this circuit it it drives the tube of pulsed DC not AC so it won't be as birght and it won't last as long. You need a push-pull driver and centre tapped transformer primary to get an AC output and drive the lamp properly.

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I know this is an old post but I believe this is fundamentally wrong.

Speaking of forward mode transformers (not flyback) and assuming the transformer is designed so that it does not saturate in any case, then the addition of a DC current at the input does not affect the output at all and, in fact, there is NO way to tell by looking at the output if there was a DC component in the input.

Look at the output transformer of a valve amplifier. It is carrying the plate DC with the output signal superimposed. The output is the AC signal with no DC. If I give you the output of two transformers and both give the same signal you cannot know which one is carrying DC in its primary. If the input is V = K + A sin(ω*t) The output will always be the same regardless of whether K is zero, positive or negative.

The thing is that if you are carrying DC in the primary then you need a bigger transformer so it does not saturate the core. The DC current is creating a continuous flux which takes the core nearer to saturation so transformers (and chokes) which carry DC in their primaries need to be specially designed but you cannot see any difference in their outputs. None whatsoever. The DC is totally blocked and it is as if it did not exist.

Just the same happens with a capacitor. If I have a signal input blocked by a capacitor, on my side I will see the AC variations but I have no idea from this side what the voltage may be on the other side of the capacitor. To know that I have to go to the other side of the capacitor. All I can see is the AC from my side.

Good point.

HS3 said:

I know this is an old post but I believe this is fundamentally wrong.

Speaking of forward mode transformers (not flyback) and assuming the transformer is designed so that it does not saturate in any case, then the addition of a DC current at the input does not affect the output at all and, in fact, there is NO way to tell by looking at the output if there was a DC component in the input.

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The circuit I am critisising is a flyback so the core does saturate. What you're saying is true that there's no DC on the secondary but there will be just negative DC pulses and no positive pulses.

I've uses a similar circuit to run a fluroscent tube from before and after a few hours of running only one end of the tube went black. This is because the current only flowed in one direction causing the cathode electrode to sputter on to the glass. Try connecting a neon lamp to this circuit and you'll see that only one electrode will glow.

Hero999 said:

That's exactly what I was talking about.
https://www.repairfaq.org/sam/samschem.htm#schmp1

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Hero, is that guy a bit full of himself or what? In the industry that circuit is called a royer inverter and was the standard inverter circuit for many, many years.

For him to say that he improved it is quite presumptuous. There has been nothing under the sun original that could be done with that circuit for almost as many years.

12v Fluo Inverter

hi

the simple project for building this 12v inverter to drive fluo lamp

few compenents, no commercial transformer

take a look here

http://www.talkingelectronics.com/te_interactive_index.html

Where's the circuit?

Hero999 said:

Where's the circuit?

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You need to search for it. I found it.

I've seen that circuit before. It uses an AM radio aerial so noise is broadcast everywhere, a single transistor and no DC blocking capacitor so one of the tube only gets driven with negative pulses causing one of tube the ends to blacken.

It's simple and low cost but also illegal (it doesn't comply with the EMC laws) and gives poor efficiency and tube life.

HS3 said:

The thing is that if you are carrying DC in the primary then you need a bigger transformer so it does not saturate the core. The DC current is creating a continuous flux which takes the core nearer to saturation so transformers (and chokes) which carry DC in their primaries need to be specially designed but you cannot see any difference in their outputs. None whatsoever. The DC is totally blocked and it is as if it did not exist.

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Actual inverters use blocking caps before the transformer because they are less expensive in money and space than a larger transformer.