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

I wonder if you could shape a parabolic mold negative(think beehive shape) then use it to cast a Fiberglas and epoxy reflector. Do your best Richard Dreyfus imitation. Whom knows? You might even be able to pick it up. Kind of like the way integrating spheres are done but in a parabola.

Holly…
Can’t wait to see all the progress and final product!

Here’s a parabolic mirror on ebay that is in bidding. As of 1:00 PM EST, it has one bid and is at $9USD. Listing says it will ship to Australia. Has free shipping.

Edit: It is 40.5cm size.

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.