[sdiy] get 5V from 12V - DC-DC converter or 7805?

[Vladimir Pantelic]

Hi FLorian,

quite a few modules use the RECOM 78xx replacement DC/DC converters, e.g. 
Mutable instruments Plaits, newer Synthesis Technologies stuff. I also use them 
on a module of mine.

have a look at the RECOM datasheet and/or the mutable Plaits schematics/layout 
for the CLC filter on the input of the DC/DC converter.

Regards,

Vladimir

On 2020-12-27 22:58, Florian Anwander wrote:
> Hello,
> 
> I am at designing the pcb for a simple  MIDI-sequencer based on an arduino nano 
> (the basic idea is derived from the JX-3P / SH-101 sequencer). I want to build 
> it as a euro rack module, but want to have it also as standalone unit. So the 
> pcb has the usual eurorack power connector and a socket for a wall wart. I have 
> jumpers to select between 5V from the euro rack connector, or 5V from a 
> regulator which is fed either by the 12V from the eurorack connector or by 
> 9V-12V from a wall wart.
> 
> At the moment I implemented the 5V conversion with a 7805. But I think this will 
> cause a lot of "useless" current on the 12V rail of the euro rack. I thought 
> about one of these DC-DC converters, but I am not sure how much 
> (switching-)noise those can insert into the euro racks supply and ground. The 
> module also has voltage inputs (for note length and velocity) and trigger/gate 
> inputs, so electric relations with ground to other modules or external devices 
> are quite likely, and I fear I transfer potential supply noise this way in the 
> external signal paths.
> 
> On the other hand the 7805 circuit is quite easy to implement, the DC-DC 
> converter has to be bought as module or requires buying parts I won't have use 
> for anywhere else.
> 
> Does anyone have experience with those DC-DC converters?
> 
> 
> Regards
> Florian
>