X-Authentication-Warning: delorie.com: mail set sender to geda-user-bounces using -f X-Recipient: geda-user AT delorie DOT com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=tkiYFAjmW9aQSTw85adCyLSUBStZA1n90812wrpP11w=; b=UYlymNb6XzqlnKgyBbYtYXsbOJqNI7iabH70RJ/5UamfynDSKVHtZPz/grguUzIwO9 DYxJUwmDhmd1Uj7TBYiZPhwqviD64nVgwzyFyTnV1HY9+eWJQ3cDol2dQ3oZrOQu/1YT Mjvm8wcyVOR/SPWPN5/qz2JgT0Tb32tIQ0LLL7xzP/mN5pGjR/O0dxQuHZ01Q+Dq2kpd lpyAILFLTvaX/FVlHNvQdCVwNAI2v3UveyNH/dDA/ffxY72kiN2PD+fDkcCrvbBczk6x K3058AtEqGsbEXR+ycXUo4MNU8vzGjDABywo6Reb8VVaAWiFJ70gl+9s/Z4vnYq8IUjP pm0g== MIME-Version: 1.0 In-Reply-To: References: <20120316142719 DOT 26210 DOT qmail AT stuge DOT se> <4F63506D DOT 90602 AT keensupport DOT net> <4F6354C2 DOT 10502 AT keensupport DOT net> <20120316150615 DOT 29273 DOT qmail AT stuge DOT se> Date: Fri, 16 Mar 2012 12:26:15 -0400 Message-ID: Subject: Re: [geda-user] Daughter's Science Fair From: Bob Paddock To: geda-user AT delorie DOT com Content-Type: text/plain; charset=ISO-8859-1 Reply-To: geda-user AT delorie DOT com Errors-To: nobody AT delorie DOT com X-Mailing-List: geda-user AT delorie DOT com X-Unsubscribes-To: listserv AT delorie DOT com Precedence: bulk On Fri, Mar 16, 2012 at 11:33 AM, Rob Butts wrote: > So if I use a 1 watt 15k ohm resistor in series with the nail and an ac > outlet that will give me 8ma alternating current and that should light the > bulb? With no isolation transformer this is not a safe approach for something in a Science Fair. Anything connected to the AC Line always presents a electrocution hazard when not isolated. Currents of less than 8 mA across the heart could kill. Two identical transformers hooked up back-to-back will get you safety isolation. For example in the past 110 in 6.3V out transformers were common. Hooking the two 6.3V sides together would get you isolated 110VAC out.