[sdiy] ROLAND PSA-120S 9VDC switching supply filtering components..

[rburnett at richieburnett.co.uk]

L1 is a differential-mode choke and will likely be wound on an iron 
powder core with quite low permeability. T1 is a common-mode choke and 
will likely be wound on a high permeability MnZn ferrite core.  They 
attenuate differential and common-mode noise respectively.

Only way to know their details would be to count the turns and measure 
the characteristics on an LCR bridge or impedance analyser.  Then you 
can make an educated guess at the part numbers of the cores from the 
inductance, turns, dimensions, etc.

-Richie.



On 2024-06-23 18:40, Jean-Pierre Desrochers via Synth-diy wrote:
> Is there anybody who made some researches on the type of inductors
> 
> used in the new Roland 9VDC switching supplies ?
> 
> The actual filtering circuit placed in series with the walwart supply
> block output is shown here
> 
> Inductor L1 and the toroid T1 are of unknown values.
> 
> I can measure them with my meters but they are mounted
> 
> On solid ferrite cores. So making them more difficult to reproduce..
> 
> I ask because I already have a bunch of surplus 9vdc at 1A SMPS blocks
> 
> acquired in the past and would like to use them to supply
> 
> some of my guitar pedals..
> 
> Using them with their 'raw' unfiltered 9vdc output makes an annoying
> 
> background noise in the audio signal path..
> 
> The 'possible' values of these 2 components, or a similar schematic
> 
> That would do the same job would be appreciated.
> 
> Thanks.
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