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Aha!</div>
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Thanks so much for the insight Florian and Tom, that makes perfect sense. I suppose then, that I should try things like reducing the bulk capacitance on the +5V line when it's derived from the +12V (and keep the bulk capacitance if I'm supplying the +5V line
separately), or try putting a low value, high current series resistor between the +12V and +5V supplies to limit the in-rush current.
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Of course these two potential solutions involve less ripple rejection, or some power wastage, so if anyone else has any other ideas, please feel free to pipe up
<span id="🙂">🙂</span><br>
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Thanks again.<br>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> Synth-diy <synth-diy-bounces@synth-diy.org> on behalf of Tom Wiltshire <tom@electricdruid.net><br>
<b>Sent:</b> Friday, November 1, 2019 1:22 AM<br>
<b>To:</b> Florian Anwander <fanwander@mnet-online.de><br>
<b>Cc:</b> Synth-Diy mailing list <synth-diy@synth-diy.org><br>
<b>Subject:</b> Re: [sdiy] Linear PSU Power Sequencing Issue</font>
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> On 31 Oct 2019, at 10:50, Florian Anwander <fanwander@mnet-online.de> wrote:<br>
> <br>
> Hi Jason<br>
> <br>
> Am 31.10.2019 um 06:17 schrieb ackolonges fds:<br>
>> and +5V (derived from the +12V line)<br>
> Even without load at the +5V rail the +12V regulator has to provide current for loading the capacitors of the +5V-supply. This effect may become even worse, if some modules have +5V regulators on board, which use the 12V for supply.<br>
> <br>
> So, my first try would be: remove the +5V supply from the +12V rail.<br>
> <br>
<br>
+1 agree with Florian. It sounds like the extra capacitance on the +12V is causing a in-rush that shuts the regulator down. This won’t happen when the caps are part-charged, so it works fine once you’ve got it started.<br>
<br>
Tom<br>
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