[sdiy] Power supply of a 19" rack

Frédéric (Opensource) marzacdev at gmail.com
Wed May 15 16:18:31 CEST 2019


Hi Justin.

Thank you for your feedback.

I totally get the principal arguments for the direct mains input.

But having the supply electronics outside the rack have still
some more great advantages:

- it won't perturb the rack electronics by emitting HF
   (which should not happen if the block is well designed)

- it won't generate heat inside the rack

- if it fails (and it's more likely than the rest of the electronics),
   it's easier to replace / repair

- the rack can be battery powered

About filtering, I guess a filtering block is an absolute
necessity for both options (mains or wall).

Have a good day,
Frédéric


Le 14/05/2019 à 23:30, Justin Herrmann a écrit :
> I prefer the mains option, but only because I hate all the space a 
> wall wart (AC to DC adapter) takes on a power strip or the wall socket 
> when you plug it in.
>
> Generating all the internal voltages yourself from mains has the 
> advantage that you can filter the mains, use linear or switching 
> regulators to create your voltages, and not have some unknown 
> frequency and amplitude of possible switching noise from a customer's 
> wall wart regulator.
>
> I do like the idea of re-using a needless adapter though.
>
> Justin
>
> On 5/14/19, 3:15 AM "Frédéric (Opensource)" <marzacdev at gmail.com> wrote:
>
>     Hi everyone.
>
>     I have not written here for a long time but I keep reading
>     the list because of the interest of the topics.
>
>     I am shared between two concepts for the power supply
>     of a 19" rack and I would like to hear your opinion both as
>     musicians and as instruments makers.
>
>     _Option A: mains_
>
>     Offering a regular 220V / 110V / 100V C14 input at the rack.
>     Inside:
>     pre-certified switched mode power supply (which adapt for all
>     countries)
>
>     Pros:
>     * C13 cables are common and available
>     * No need for an external wall adapter
>     * Musicians seem to like this (my impression)
>
>     Cons:
>     * Certification process (more complex and costly)
>     * Design risks (mains inside / grounding / security for users and
>     technicians)
>     * Big additional cost
>
>     _Option B: all in_
>
>     Offering a regular 2.1mm DC jack connector that can accept ANYTHING
>     like DC/AC from 6V to 16V.
>     Inside:
>     rectifier + small DC/DC converter or linear regulation
>     (depending on the consumption and dissipation of the circuits)
>
>     Pros:
>     * Everyone owns needless adapters that could be reused
>        (= environment friendly / less e-waste)
>     * Less design complexity
>     * No mains inside the rack
>     * Simplified certification process
>
>     Cons:
>     * Need an external power adapter
>     * Need a power adapter that works for the region where the machine
>     is used
>        (simple wall transformers often cannot travel)
>     * Musicians don't seem to like it (my impression)
>
>     Question:
>     What would you prefer?
>
>     Fred.
>
>     PS: By the way, last hours for the Buzzzy! on Kickstarter:
>     https://www.kickstarter.com/projects/1304489933/buzzzy-the-digital-polysynth
>
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