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PO89ZB , an inline DC filter for SMPS wall warts . Preamps, HPA, Korg NuTube, etc
PO89ZB , an inline DC filter for SMPS wall warts . Preamps, HPA, Korg NuTube, etc
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Old 5th May 2021, 01:39 PM   #661
merlin el mago is offline merlin el mago  Catalonia
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Quote:
Originally Posted by coolnose View Post
I think any that is above your SMPS voltage should be ok, and pls note it's technically not a Zener:

Difference between TVS Diodes and Zener Diodes (1) | Toshiba Electronic Devices & Storage Corporation | Europe(EMEA)

I looked it up because it trigggered me, but that few lines are sufficient for me, I won't dig into it any further.
Thank you.
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Old 6th May 2021, 01:02 AM   #662
ranshdow is offline ranshdow  United States
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Default SMPS DC filter for RPi

So the HAT boards I designed with Mark's SMPS inline DC filter circuit came in. I tested all 10 with a USB-C RPi power supply plugged in to the SMT receptacle and I can read 5.26V across the spot where the TVS goes, so the USB-C receptacles were mounted properly, though 4 of them are a bit crooked- just cosmetics. The two mounting spots for the 40-pin GPIO, one for direct-mount on top of a RPi, one for mounting on top of a HiFiBerry DAC or similar card in the lower position, look like they align as well (see the pictures). I'll be building up a couple and testing them with my RPi and sound cards over the next few weeks, time permitting, so I don't know yet if they actually work!


I have 7 of these bare boards to spare, to anyone looking to test and play with them. In the spirit of thanks to the diyaudio community, to Mark for designing and sharing this useful little filter with us, and to avdesignguru for encouraging me to teach myself KiCad and for reviewing the design, I offer these 7 for free to the first 7 people who pm me for them. I can even throw in a 40-pin header and a couple of jumpers if you'd like. For international folks, I ask that you consider reimbursing me for postage; for US folks I'll cover it.
Attached Images
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File Type: jpg IMG_5295.jpg (716.0 KB, 145 views)
File Type: jpg IMG_5296.jpg (689.5 KB, 129 views)
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Old 6th May 2021, 11:38 AM   #663
Mark Johnson is offline Mark Johnson  United States
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PO89ZB , an inline DC filter for SMPS wall warts . Preamps, HPA, Korg NuTube, etc
Lovely 3D arrangement! Congratulations. When the filter board is mounted atop the board with the two RCA jacks, one white and one red, it instantly becomes clear why there's a notch in your PCB. Please let us know how well it works when playing music.
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Old 7th May 2021, 02:51 AM   #664
ranshdow is offline ranshdow  United States
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Thanks, Mark! I didn't get as far as music today on account of some unresolved library file issues, but I did get through power up. I didn't see any under-voltage lightning bolts from the Pi (4.6V or so); the lowest I measured across the output with a cheap DMM was 5.05V, so hooray. Across the first current sense resistor which sees 5.26V I measured voltage drops of 25mV at idle (625mA I guess), up to 54mV (1.35A) under disk copying, so well under the 3A rating of the circuit and the wall wart. Also hooray.
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File Type: jpg IMG_5299.jpg (664.1 KB, 184 views)
File Type: jpg IMG_5300.jpg (574.3 KB, 179 views)
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Old 8th May 2021, 03:47 PM   #665
ranshdow is offline ranshdow  United States
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I have 5 of these boards left if anyone else is interested.
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Old 14th May 2021, 07:04 AM   #666
nerone is offline nerone
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Hello everyone, on diyAudio Store the Kit is finished, do you know if it will be available again?
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Old 15th May 2021, 02:37 AM   #667
avdesignguru is offline avdesignguru  United States
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Default Split Rail vs CT Transformer

I built a bipolar version of this filter and put it downstream of a Mean Well NSD15-48D15 15 watt DC-DC regulated dual output converter to create a filtered +15/-15V SMPS supply. This was for a headphone amplifier I had recently built. The Mean Well converter accepts 18 - 72VDC so I used a Mean Well GST25U24-P1J 24VDC 1A single output SMPS that I had on the shelf.

It ended up sounding better than the 20 watt regulated bipolar linear power supply that I had been using. Very tight and well defined in the bass but not "bass heavy". I wonder if this is because the converter might provide a better ground reference? Better than a dual secondary or center tapped transformer design? Also I noticed enhanced clarity across the entire audio range with no loss of smoothness in the sound. This I attribute to the noise filters.

Thank you, Mark, for sharing this excellent filter design.
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Old 15th May 2021, 04:03 AM   #668
Vunce is offline Vunce  United States
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PO89ZB , an inline DC filter for SMPS wall warts . Preamps, HPA, Korg NuTube, etc
Hi Avdesignguru,
Nice bipolar filter layout
Did you also have a pcb made for the MeanWell NSD15-48D15?
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Old 15th May 2021, 11:42 AM   #669
Mark Johnson is offline Mark Johnson  United States
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PO89ZB , an inline DC filter for SMPS wall warts . Preamps, HPA, Korg NuTube, etc
Congratulations, @avdesignguru! I am delighted that your dual filter worked so well, and noticeably improved the sound of your gear. I hope you included the TVS protection diodes on your board, since in a bipolar supply + bipolar filter there are so many ways to make a wrong connection. You don't want to explode a capacitor (or a Mean Well converter module) during setup!
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Old 15th May 2021, 04:34 PM   #670
avdesignguru is offline avdesignguru  United States
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I'm currently listening to an outboard converter connected to my dual filter PCB which includes the TVS diodes. The attached schematic and board design is in production, soon to be on its way to me.

Unfortunately, the Mean Well NSD15-48D15 is in a very low stock situation at Mouser and is currently non-stock at DigiKey. There is a Phoenix, USA distributor that I have not used, onlinecomponents.com, that shows qty=55 in stock. Perhaps this product is just too new to be popular yet, as the spec sheet is dated 10/20/2020.
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File Type: pdf MWRSF Schematic V1_0.pdf (49.6 KB, 41 views)
File Type: zip MWRSF-V1.zip (92.1 KB, 21 views)
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