Ballast designs for 70W MH bulb?

[Willmore]

I was lucky a few months ago and got a pack of four 70W MH bulbs made by philips. Since then, I've been casting about for a decent ballast design for them.

I've read about the automotive ballast controller chips and they look great--but, I was cautioned by a fellow at philips that their bulbs do *not* like constant wattage startup like automotive bulbs can handle. Since that's a standard feature in all of the auto ballast chips that I've come across, that precludes their use.

I saw a design at Don's web site, but it's for a smaller bulb, looks a bit 'iffy', and has construction details that make me blanch. I don't like the idea of making a split core transformer with a hack saw.

Maybe something a bit more 'off the shelf'.

Does anyone have any suggetsions? I'd perfer an electronic design with a high frequency square wave output, but it looks more and more like I'm not going to find that.

Thanks!

 

[hotfoot]

Dunno if this will help, but this link has been posted here before:
http://www.madhacker.org/sublight.htm

He can handle up to 3 75W halogen bulbs...

 

[Willmore]

Those are just halogen bulbs. Driving those is a simple matter of a DC-DC boost or buck converter/regulator. I do like his design, though!

I'm looking for a ckt to drive 70W Metal Hallide (HID) bulbs. They're a bit higher voltage and somewhat 'stranger' electronically.

 

[snakebite]

check this out if you like to homebrew.


hid ballast plans

 

[Willmore]

That's the one I was refering to as being a bit 'iffy'. Even if it works great, it's still too low power to handle a 70W bulb. That claims to work for 30W bulbs, but not larger. Don K's website has that document linked from it and I read it about a half year ago--when I began my search.

Thanks for bringing it up, though.

 

[snakebite]

check my post in buy sell trade for something that may do if you like to experiment.