<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12px"><div id="yui_3_16_0_1_1436877118891_203954"><span>Dwight,</span></div><div id="yui_3_16_0_1_1436877118891_203954"><span><br></span></div><div id="yui_3_16_0_1_1436877118891_203954">A good method for dc power supply is to have two diodes in parallel. The primary source should have a higher voltage and will prevent the secondary source from suppling power. If the primary dies the secondary will kick in. So if the case is a wall power and battery power, then make sure you tie the grounds together and make sure the wall volatage is higher than the battery voltage.</div><div id="yui_3_16_0_1_1436877118891_203954"><br></div><div id="yui_3_16_0_1_1436877118891_203954">John Vaughters</div> <br><div class="qtdSeparateBR"><br><br></div><div class="yahoo_quoted" style="display: block;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12px;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div dir="ltr"> <font size="2" face="Arial"> On Wednesday, July 15, 2015 10:14 AM, Dwight Morgan via TriEmbed <triembed@triembed.org> wrote:<br> </font> </div> <br><br> <div class="y_msg_container"><div id="yiv1069042944"><style><!--
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--></style><div><div class="yiv1069042944WordSection1"><div class="yiv1069042944MsoNormal">Hi All:</div><div class="yiv1069042944MsoNormal"> </div><div class="yiv1069042944MsoNormal">I need a backup power supply for my Raspberry Pi 2. I don’t think I need something as large as those made for PCs. I think one more in line with that D cell powered one in my alarm clock or a little larger would work fine. </div><div class="yiv1069042944MsoNormal"> </div><div class="yiv1069042944MsoNormal">Anybody know how to make one or if there is one out there already? Feedback appreciated!</div><div class="yiv1069042944MsoNormal"> </div><div class="yiv1069042944MsoNormal">Thanks!</div><div class="yiv1069042944MsoNormal"> </div><div class="yiv1069042944MsoNormal">Dwight</div><div class="yiv1069042944MsoNormal"> </div></div></div></div><br>_______________________________________________<br>Triangle, NC Embedded Computing mailing list<br><a ymailto="mailto:TriEmbed@triembed.org" href="mailto:TriEmbed@triembed.org">TriEmbed@triembed.org</a><br><a href="http://mail.triembed.org/mailman/listinfo/triembed_triembed.org" target="_blank">http://mail.triembed.org/mailman/listinfo/triembed_triembed.org</a><br>TriEmbed web site: <a href="http://triembed.org/" target="_blank">http://TriEmbed.org</a><br><br><br></div> </div> </div> </div></div></body></html>