[sdiy] Eurorack Power Protection

Pete Hartman pete.hartman at gmail.com
Tue Jan 3 22:02:22 CET 2017

I don't like the 10R resistors, because a power hungry module will cause
itself supply instability.  I've seen this on a couple of VCOs, for example.

I usually put PTC fuses in that position, and run the diodes, reverse
biased, to ground.  If you plug that in backwards, it trips the fuses
generally before bad things can happen further down the line.

I also don't usually put .1uF caps at the power inlet, I just use them to
bypass each chip's supply pin or pins.

I recommend using shrouded headers on a Euro module -- yes, bad cables can
still be plugged in backwards, but it's sufficient to allow me to safely
plug a known-good cable in without having to physically look at the place
I'm plugging in (say, inside my case).

Now I will sit back and allow myself to be schooled by the more experienced
about why what I'm doing is wrong :-D.


On Tue, Jan 3, 2017 at 2:41 PM, Jacob Watters <jacobwatters at gmail.com>

> Do you do anything to the power rails on your modules to filter the power
> and/or protect the module?
> Diodes? Caps? Resistors?
> Below is a link to one well protected module that was recommended to me.
> Note that the power source is the pins on P3 and the power rails are the
> local ones on the module (kind of confusing in this schematic - it looks
> like the diodes are backwards).
> I know that the diodes will cause a voltage drop that will limit the
> overhead for opamps. My module is a filter with an overdrive circuit that
> clips at +/-5V, so overhead isn't really a concern.
> http://jacobwatters.com/images/synth/europower.png
> Thank you for your feedback and suggestions.
> Sincerely,
> Jacob Watters
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