Hi Text,
By HID lighting I take it you mean High Intensity Discharge lighting.
HID encompasses the following types of lighting:
- Mercury Vapour.
- Sodium Discharge (High and Low Pressure types).
- Metal Halide.
Please bear in mind that some lamps have thier own starting gear inside the lamp itself, (called a Self-Ballasted lamp) and others require a ballast matched to the wattage of the lamp to be used.
There really isn't much difference between the various shapes of lamps, it just depends upon what type of fitting the lamp is being used in.
I wouldn't personally intermix lamps and ballasts of different wattages, the lamp may not like it too much.
Sorry I can't help with any circuit diagrams, but I think Scott35 has some diagrams in the Technical Reference area, if I remember correctly.
One thing I do know is that you need an Ignitor unit on Metal Halide lamps to strike the lamp.
Here's some links to some circuit diagrams in the Tech Ref. area.
First link Second link Discussion on HID Ballasts Hope that this is of some help.
Mike :]
{Message edited to add in links}
[This message has been edited by Trumpy (edited 10-06-2004).]