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Date:	Fri, 16 Mar 2012 16:59:29 -0400
From:	Vanessa Ezekowitz <vanessaezekowitz AT gmail DOT com>
To:	geda-user AT delorie DOT com
Subject:	Re: [geda-user] Daughter's Science Fair
Message-ID:	<20120316165929.07979000@rainbird>
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You guys are missing one of the fundamental ideas for this kind of project:  a chopper circuit.

Connect a few batteries, a switch, the coil of a low-voltage relay, and the "normally closed" switch in the relay in series with one of your coils (your primary) on the nail:

battery -> relay coil -> relay normally closed switch -
-> your power switch -> your primary coil -> back to battery

Connect the other coil (your secondary) on the nail to your light bulb (or better, an LED).

When you close the switch, assuming the batteries add up to enough voltage, the relay will start cycling rapidly, "chopping up" the DC and inducing something not too different from an AC voltage in your primary coil.

That should, in turn, induce a voltage in your secondary and light your bulb/LED/whatever.

Yes, it'll wear the relay out after a while, but its not like this needs to last more than a couple of days anyway.

-- 
"There are some things in life worth obsessing over.  Most
things aren't, and when you learn that, life improves."
http://digitalaudioconcepts.com
Vanessa Ezekowitz <vanessaezekowitz AT gmail DOT com>

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