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Hi All,</div>
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Since everyone's talking about power supplies, I thought I might mention a power supply issue I've been having - maybe one of you has had (and solved?) this issue before.</div>
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Basically I've been building some straightforward linear power supplies for my modular system with 1A +12V,-12V and +5V (derived from the +12V line) outputs. They are using 12V toroidal transformers, going into custom PCBs with plenty of bulk and localized
bypassing, a bunch of diodes, 7812s, 7912s, and 7805s, similar to the power supply on the MFOS website among others.
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The issue is that sometimes when I power up a unit with modules plugged in, the +12V rail does not power up properly (the indicator LED does not light), but if I switch the power off for a short time and back on before the caps have discharged, the +12V rails
powers up fine. <br>
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Has anyone else had this type of (power sequencing?) problem before, and if so, how did you solve it? I couldn't find any information about this in the datasheet, and tried regulators from a number of different manufacturers to no avail. It also seems to happen
at certain loads (not necessarily high loads), and not at others.</div>
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Thanks a lot for any advice or ideas you may have!</div>
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Jason<br>
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