Two parallel diodes reverse biased won't short out the supply, they just wont allow current to get to the circuit.<br>For the price of about $0.015, I just use four 1N914 small signal diodes in a full wave bridge configuration. That just supplies the correct power to the rest of the circuit regardless of if the polarity is reversed. The voltage drop from the mains is 0.6V to 0.7V per leg. Minimal drop considering the existing overhead.<br>Since they're small signal diodes, they can handle around 1/3A and have less reverse bias leakage (and cost less) than 1N40XX series. They also double as a fusible link if the circuitry faults.<br>Obviously, if they connect everything correctly, two diodes just sit there.<br><br><br>Sent from XFINITY Connect Application<br><br><br>-----Original Message-----<br><br>From: pete.hartman@gmail.com<br>To: mskala@ansuz.sooke.bc.ca<br>Cc: synth-diy@synth-diy.org<br>Sent: 2017-10-21 2:41:48 PM <br>Subject: Re: [sdiy] Euro Synth Spec<br><br><html><div dir="auto">And in that latter case usually we put ptc fuses in line as well so we DON'T actually damage the supply or other modules.<div dir="auto"><br></div><div dir="auto">I do diy, not commercial modules, but the same logic applies.</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Oct 21, 2017 3:24 PM, <<a href="mailto:mskala@ansuz.sooke.bc.ca" >mskala@ansuz.sooke.bc.ca</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On Sat, 21 Oct 2017, Ben Bradley wrote:<br>
> Do many or any Euro modules have reverse-polarity protection? It seems<br>
> easy enough to add a series Schottky rectifier in series with each<br>
> power line, but it adds parts cost and drops a little voltage where<br>
> people are already thinking the 12V supplies should be 15V.<br>
<br>
Many; not all. Some do it in other ways, such as with parallel diodes<br>
that will be reverse-biased in normal operation and effectively short out<br>
the power supply when the connection is backwards.<br>
<br>
--<br>
Matthew Skala<br>
<a href="mailto:mskala@ansuz.sooke.bc.ca" >mskala@ansuz.sooke.bc.ca</a> People before principles.<br>
<a href="http://ansuz.sooke.bc.ca/" rel="noreferrer" >http://ansuz.sooke.bc.ca/</a><br>
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