I have noticed that some digrams juts show a ballast whereas others show a ballast, ignitor and capacitor. I have searched around the forum but cant seem to find and answer. Why is this?

Also, does anyone know where i can get a cheap ballast (and ignitor and capacitor if necessary) in the UK so i can avoid the extra shipping costs?

Thanks to everyone on advance.

Rory

I think it's the difference between "pulse-strike" and normal bulbs. PS bulbs need an ignitor to make the pulses? Someone correct or confirm this for me.

It would be really nice to know the make and model of the lamp you plan on using.

Due to cost ive tried to find the cheapest one possible. - http://www.directlight.co.uk/hit_e40_400w_hid_lamp

Well... there isn't much info on that lamp. It doesn't list the color temperature or the CRI. Personally, I wouldn't buy it.
You might want to check out the Best Bulbs Chart and search for a UK vendor who sells one of those.

OK. Thanks

Ive found a Ushio S400DD from a company that ships to the UK (bulbster). However i could get this bulb at nearly half the price. It is 400W 5K but doesnt give a lumen rating. What do you think?

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?Vie...em=250155053116

(From the description I can see that this one does need an ignitor as well as ballast)

Magnetic ballasts must have at least an external capacitor, and sometimes an ignitor in the circuit. Electronic ballasts don't. (Well, they also do, but they're integrated into the ballast housing.)

Also, wiring diagrams will tend to treat the ballast as though it just needs power, and powers the lamp. The individual components can be ignored in a wiring diagram, when the main focus is switches and cooling

OK. Thanks.

What do you think of the ebay bulb VS the ushio one?

From memory, the Ushio S400DD is 5200K colour temp, 32,000 lumens mean. This makes is a bit dimmer than the LL lamp, and a bit lower colour temp. It's still a fine lamp, and is what is still in my S15 projector.

The biggest advantage to it is the ability to use a HPS ballast (ANSI S51) instead of the MH ballast. It also seems to be much easier to start than the regular MH lamps, because it is a retrofit lamp.