Ballast for fluorescent tubes

I want to build a circuit to drive 6 fluorescent tubes, the tubes are 15W each.

I haven’t done this before so there are a couple of things I’m not sure about.

Is the ballast just an inductor and if so is the size of inductance needed related to the power of the tube

What is the ballast doing anyway?

I think its doing two things but I’m not sure so does this sound right to you?

The starter closes, a high current flows through the filaments to heat them.
The current is limited by the ballast.

The starter opens, a high voltage spike is produced by the inductor, this spike initiates the flow of current through the tube.

Once the tube is running, (I’m really really not sure here because I don’t know the inductance or how much current a running tube would attempt to draw)

Either the ballast is effectively negligible or the ballast is limiting the amount of current drawn by the tube.

Any advice is much appreciated

Many Thanks

If You mean the electronic ballast - it's not the inductor_starter based scheme at all. It is a special kind of swiching power supply circuit driving the lamp with relatively high frequency (~10 kHz or so).To learn more about specific ballast circuits & apps visit this page:
http://www.irf.com/product-info/lighting/
You can search the site with the "ballast" keyword

Other option is to buy 6 15W fluorescent lights with the electronics built-in and just gently remove these circuits from bases and use them in your application.
At the cost of a conventional balast and starter you have ready to go electronic circuit of the size of a <40mm disk..

Hello Engineer_Bob,

There's an excellent FAQ on fluorescent lights, ballasts and how to use them here:

https://members.misty.com/don/f-lamp.html

FoxyRick.

Many thanks to you all, I’m building a double sided UV exposure box for PCB’s, if the projects successful, I’ll post the details on the forum.


Kind Regards Engineer Bob