# Help Reconstructing the Solar-Powered 1920’s style Death Ray from my Youth

**URL:** <https://boards.straightdope.com/t/help-reconstructing-the-solar-powered-1920-s-style-death-ray-from-my-youth/378279>\
**Category:** Factual Questions\
**Created:** [October 28, 2006, 9:49pm UTC](https://boards.straightdope.com/t/help-reconstructing-the-solar-powered-1920-s-style-death-ray-from-my-youth/378279 "2006-10-28T21:49:58Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![kjckjc](https://avatars.discourse-cdn.com/v4/letter/k/e36b37/32.png) [@kjckjc](https://boards.straightdope.com/u/kjckjc)\
**Post date:** [October 28, 2006, 9:49pm UTC](https://boards.straightdope.com/t/help-reconstructing-the-solar-powered-1920-s-style-death-ray-from-my-youth/378279/1 "2006-10-28T21:49:58Z")

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When I was about 10-12 my dad had a concave mirror that believe came from a telescope of some sort. It was about 10” in diameter. He demonstrated that it worked much better as a death ray for green army men than a simple magnifying glass. It broke a few years later. I would like to purchase another one. But I don’t know what I should look for as far as getting one that will do what I want. The focal length, if that is the right term, was about a foot from the mirror if I recall. It was close enough to let you hold what you were melting/burning but also keep your hands out of the way of the mirror. I would like one about 10” in diameter also I think, it seemed like a good size. I am also not terribly rich. So where should I look (science supply store?) and what specs do I need to look for?

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**Author:** ![daffyduck](https://avatars.discourse-cdn.com/v4/letter/d/ec9cab/32.png) [@daffyduck](https://boards.straightdope.com/u/daffyduck)\
**Post date:** [October 29, 2006, 3:53am UTC](https://boards.straightdope.com/t/help-reconstructing-the-solar-powered-1920-s-style-death-ray-from-my-youth/378279/2 "2006-10-29T03:53:38Z")

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There’s one with some minor flaws available on eBay for $10. Sounds perfect for playing around with.

Item # 140046940755

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**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\
**Post date:** [October 29, 2006, 4:18am UTC](https://boards.straightdope.com/t/help-reconstructing-the-solar-powered-1920-s-style-death-ray-from-my-youth/378279/3 "2006-10-29T04:18:33Z")

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The mirror in the Edmund [solar energy lab](http://scientificsonline.com/product.asp_Q_pn_E_3042427) looks to be about the right size, and it’s cheap!  
At 8X the cost, their [solar furnace](http://scientificsonline.com/product.asp_Q_pn_E_3001413) is spiffier looking.

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**Author:** ![Ike\_Witt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ike_witt/32/283_2.png) [@Ike\_Witt](https://boards.straightdope.com/u/Ike_Witt)\
**Post date:** [October 29, 2006, 5:46am UTC](https://boards.straightdope.com/t/help-reconstructing-the-solar-powered-1920-s-style-death-ray-from-my-youth/378279/4 "2006-10-29T05:46:16Z")

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[QUOTE=Squink]  
their [solar furnace](http://scientificsonline.com/product.asp_Q_pn_E_3001413) is spiffier looking.  
[/QUOTE]

Lol. Disadvantages - Doesn’t work at night.

That’s okay I have a lunar furnace for nights.