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GB for Simple Cap-Mx Regulated Low-Noise PSU

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#64
Good morning

I have an interest in this GB for my Rpi and DAC Hat .

I dont have many smps but do have plenty toroid and diode bridges. Is it ok to feed this straight into the board offered here.?

And do you have pcbs left?
Is there just the one surface mount R to deal with?!

Regards
James
 
#67
Hi, X

A quick question on this PSU. If I am going to use a SMPS as the primary voltage supply, feeding through a Buck converter to either step up or down the voltage, then thru a CLR filter, thru the capMx and finally thru another low noise LDO regulator which has very high PSRR, is the capMx really necessary? Don't get me wrong, I am sure the capMx will further improve the "cleanliness" of the power. My thought is that since the SMPS, BC, CLC, and the LTXXXX all have filtering capability, and the regular ripple (120 Hz) is practically absent, do you think one can leave out the capMx? I am trying to make the PSU with a minimum number of components as possible (provided a sufficiently clean power supply is achievable).

Lastly, the SMPS and I am planning to use has multiple outputs, do you think I can hook up two of your capMx PSU to it and then connect the output in series to make a dual rail (+/-) supply. The 0V ground point will be the ground connector at the SMPS. Basically, I am setting it up like using a transformer with dual secondaries that are feeding to two bridge rectifiers with filters.

Thank you very much in advance for answering my questions. Much appreciated1

Regards,
 
#68
The cap Mx, in addition to providing ripple reductions, has a very important function of ramping the voltage and current and voltage up slowly so that the self-protect circuitry in a SMPS doesn’t shut the SMPS off due to in rush current to a large cap or amp input demand. It also prevents turn on speaker pop noise. The voltage takes about 5 seconds to fully rise to steady state.
 
#69
xrk971 said:
I forgot to include the choke L101. Something like a ferrite core toroidal EMI filter with approximate 5A capability and circa 10uH value is good. 8mm hole pitch, 19mm dia max, 10mm thick max.
Click to expand...

Hi XRK, trying to order parts. Mouser does not seem to have anything that comes close to these specs. The ones around 5A all have a much larger diameter. Looking at this datasheet, it would have to be =< 1.4A to fit the 19mm. Is the spec correct? If so, any suggestions?
 
#71
xrk971 said:
The cap Mx, in addition to providing ripple reductions, has a very important function of ramping the voltage and current and voltage up slowly so that the self-protect circuitry in a SMPS doesn’t shut the SMPS off due to in rush current to a large cap or amp input demand. It also prevents turn on speaker pop noise. The voltage takes about 5 seconds to fully rise to steady state.
Click to expand...

Thank you for the explanation.

Regards,
 
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