FmC's Hand Made DIY 2015 comp entry; "WW2 Searchlight". Finished!

68 cm focal length. At that distance you would need an intermediate lens to get the light onto the surface.

Thanks for the discussion, guys.

Believe me, I spent a lot of time searching on-line for something suitable, with a reasonable price.

I'm choking on forking out for four XHP's, never mind ~$150 for a reflector...

I have some "97%" reflective flexible adhesive mirror squares in the mail, so I'm really just looking for a suitable shape to coat with them, although a 'ready to go' reflector would be nice.

Explain to me why I can't use the satellite dish if it's tilted on an angle, or if the emitters are off-center?

:beer:

I assume you have seen

It's ideal, apart from;

"Asking 325
Shipping 18

U.S. Only"

:)

You can, however the focal length is a bit long.

Cheers David

Thanks David, got it :)

The search continues...

For the record… I absolutely love that statement. :beer: Pure brilliance! I want to use that as my sign off line. :smiley:

Go for it! :wink: I guess I was too dumb to know how brilliant I was being. :stuck_out_tongue:

This seems to be the best option I can find in a pre-made solution. Almost perfect size for the body I have, good focal length, only costs half the earth... I know I can get it in a couple of days, being local to me. Not sure what impact the small hole in the center would have, but I could patch that with some reflective material.

Of course, the other solution is to make something.... after a bit more searching, I came across this site, which made understanding the parabola easier for me.

I'm also planning to make a few cardboard parabola cut-outs that I can take to the dollar-store, in the hope that they may have a dish/bowl that just happens to have a parabolic contour.

That Edmund Optics mirror looks so perfect! Have fun trying to find/make something. Hope it goes well for you. I’m looking forward to seeing your finished product!

That 40.5cm mirror I linked earlier is still at one bid $9USD and has 14 hours left to go. It will probably end up well below the $62 price of that Edmund Optics mirror. If nobody else bids on it, somebody’s gonna get it for $9USD. It can ship to Australia, and shipping is free. :slight_smile:

That mirror looks great, but too long a focal length, & a little too large. Also, I don't think they are going to ship for 'free' somehow :)

There's quite a few places selling it, & the cheapest I could get one for is around $145.

Maybe for a long focal length like that, you could use a microwave dish. It seems the main problem would be getting it smooth and shiny. A simple way might be to cover it with aluminum foil.

I spent a little time yesterday making a parabolic cut-out. I'll take it with me to the shops today, on the chance that I find a bowl or something with the same contour.

And a question for the driver gurus;

If I were to piggyback 3 or 4 FET's on the same board, will the 13a have a strong enough drive signal to operate them all?

With a nice high gate voltage a good FET can run up to 100A.

Feel free to chime in over here...

Little bit of progress yesterday in post #1.

Actually, It may have been a step backwards.... :~

& a small step forward today in post #2.

Sorry to hear about the set back, but it's great to see you have a sense of humor about it with "Jack" and all.

A little more progress today in post#3.

At least the write-up is already excellent, great reading, that will impress the judges as well :-) , I hope that the mirror will work out in the end. Keep going!!!