Inductor and Cap specs for the C2C boards

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bobbass4k

New member
More thinking out loud and hoping for some feedback - Sourcing parts for a few C2C boards, the inductor that's specced in from Tayda is rated at 2.1A (DC saturation current) - this one. Trying to source parts from elsewhere I can't find any 100uH inductors at 2.1A in that form factor (5mm pitch and 18mm height). Presumably the inductor is only handling as much current as the circuit will draw, which is sub 1A, so a 1.5A is probably fine? The only 2A I can find is too big for the PCB and case.

Also has anyone had any issue with the HV caps? The BOM specifies 250V but if the HV is running at 200V to 250V, I usually like to run caps with a lot more headroom but 450V ones also won't fit in the case without being folded over.
 
bobbass4k said:
More thinking out loud and hoping for some feedback - Sourcing parts for a few C2C boards, the inductor that's specced in from Tayda is rated at 2.1A (DC saturation current) - this one. Trying to source parts from elsewhere I can't find any 100uH inductors at 2.1A in that form factor (5mm pitch and 18mm height). Presumably the inductor is only handling as much current as the circuit will draw, which is sub 1A, so a 1.5A is probably fine? The only 2A I can find is too big for the PCB and case.

Also has anyone had any issue with the HV caps? The BOM specifies 250V but if the HV is running at 200V to 250V, I usually like to run caps with a lot more headroom but 450V ones also won't fit in the case without being folded over.
Click to expand...
FWIW, I’m considering using larger enclosures for some C2C boards, though I’m not sure yet what would be involved with converting the Tayda drill templates for that. I haven’t actually begun ordering parts yet, tho have bought a few boards from Nathan recently.

The 1/4” jacks seem like they have enough clearance w the board to not be too concerned about it all, and I trust the designs, but I haven’t yet traced out where the high voltage is in relation to everything, and people only seem to ever show build shots w/o stuff connected, so I’d be more comfortable knowing. It is a high enough voltage imo for consideration.
 
In the interim, I’m going to use the enclosure from an old TubeMP preamp that I somehow managed to blow up in order to house some experiments, and maybe use some kind of wooden frame for added safety until I can work it all out.

Likely a lot less safe than any of the prescribed builds 😂, but there you have it. I think the designs are safe the way they are, but there’s always margins of safety that are somewhat subjective.
 
Smrtokvitek said:
I use Nichicon UPW series capacitors in these types of circuits.


It is probably the smallest low ESR cap with a high enough voltage rating from a reputable brand you can buy. Anything with a higher voltage rating will be larger or probably from some sketchy brand.
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Got this from bing about Nichicon caps (using gpt4), it says they’re good for audio equipment use, tho it also says some say they aren’t durable and can fail prematurely, but it doesn’t provide linked sources for that.. and I don’t have enough experience to say one way or the other. I’ve used them before for something high voltage, non-audio related and they worked fine.


/* bing’s reply to the prompt “Nichicon UPW series capacitors, are they any good?”

Nichicon UPW series capacitors are aluminum electrolytic capacitors that are designed for switching power supplies. They have a low impedance, high reliability, and a long lifetime rating. They are also compliant with the RoHS directive and AEC-Q200 qualified for automotive applications¹²³.

According to some reviews, Nichicon UPW series capacitors are good for general-purpose use, especially for audio and video equipment. They have a low ESR (equivalent series resistance) and a high ripple current rating, which means they can handle high-frequency noise and voltage fluctuations. They also have a good temperature range and stability .

However, some users have reported that Nichicon UPW series capacitors are not very durable and can fail prematurely. They may also have a high leakage current and a low capacitance tolerance, which can affect the performance and efficiency of the circuit. Some users have suggested using other Nichicon series, such as UHE, UHW, or UFW, for more demanding applications.

Therefore, Nichicon UPW series capacitors are good for some applications, but not for others. It depends on the specifications and requirements of the circuit and the device. You may want to compare different Nichicon series and other brands of capacitors before making a decision. I hope this helps. 😊

¹: ALUMINUM ELECTROLYTIC CAPACITORS UPW - NICHICON
²: UPW

Source: Conversation with Bing, 2024-01-03
(1) ALUMINUM ELECTROLYTIC CAPACITORS UPW - NICHICON. https://www.nichicon.co.jp/english/series_items/catalog_pdf/e-upw.pdf.
(2) UPW Aluminum Electrolytic Capacitors - Nichicon | Mouser. https://www.mouser.ca/new/nichicon/nichicon-pw-capacitors/.
(3) UPW Aluminum Electrolytic Capacitors - Nichicon | Mouser. https://www.mouser.co.uk/new/nichicon/nichicon-pw-capacitors.
*/


FWIW, Jackcon is the brand that was in that ART TubeMP Studio, and it was one of them that went up in blue smoke. Didn’t think I really had pushed the device, maybe used too hot of an input signal? That cap wasn’t high voltage, just 63v rated and that preamp is a starved plate design, not high voltage. [Edit - actually it was 16v rated, some of the other caps in it are rated 63v. Too distracted right now. Maybe a jolt would help with focus lol 😝 ]

Electrolytic Capacitor｜Aluminum Electrolytic Capacitor｜Electric Capacitor｜Jackcon SMD Electrolytic Capacitor

Electrolytic capacitor are general purpose, high reliability. Jackcon provides total solution of electric capacitor, including aluminum electrolytic capacitor, smd electrolytic capacitor, aluminum solid capacitor, radial and axial aluminum electrolytic capacitors.
www.jackcon.com.tw www.jackcon.com.tw

edit: sorry, it was Panasonic caps I’d used before, just checked.
 
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bobbass4k said:
More thinking out loud and hoping for some feedback - Sourcing parts for a few C2C boards, the inductor that's specced in from Tayda is rated at 2.1A (DC saturation current) - this one. Trying to source parts from elsewhere I can't find any 100uH inductors at 2.1A in that form factor (5mm pitch and 18mm height). Presumably the inductor is only handling as much current as the circuit will draw, which is sub 1A, so a 1.5A is probably fine? The only 2A I can find is too big for the PCB and case.

Also has anyone had any issue with the HV caps? The BOM specifies 250V but if the HV is running at 200V to 250V, I usually like to run caps with a lot more headroom but 450V ones also won't fit in the case without being folded over.
Click to expand...
The exact current spec of the inductor is not critical. For my SMD builds I typically use an inductor that is rated for 1.8A, I've gone as low as 1.2A and it was fine. I've also gone as high as 3A, doesn't matter. I used to get through-hole power inductors from Mouser that were similar before Tayda started offering them, I'm sure Mouser still has some suitable offerings.

There are plenty of 400V rated capacitors that have the same pin spacing as the 250V ones I recommend. I use them on my personal builds that run 350V on the HV rail. That being said with the 220k+4k7/560R setup you shouldn't exceed 235V on the output, and since the SMPS is regulated the output does not depend on the input, meaning you won't have any output spikes that exceed the rating of the caps. That's why I'm comfortable designing for 250V caps.
 
vigilante398 said:
The exact current spec of the inductor is not critical. For my SMD builds I typically use an inductor that is rated for 1.8A, I've gone as low as 1.2A and it was fine. I've also gone as high as 3A, doesn't matter. I used to get through-hole power inductors from Mouser that were similar before Tayda started offering them, I'm sure Mouser still has some suitable offerings.

There are plenty of 400V rated capacitors that have the same pin spacing as the 250V ones I recommend. I use them on my personal builds that run 350V on the HV rail. That being said with the 220k+4k7/560R setup you shouldn't exceed 235V on the output, and since the SMPS is regulated the output does not depend on the input, meaning you won't have any output spikes that exceed the rating of the caps. That's why I'm comfortable designing for 250V caps.
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Yeah the regulated output is what made me OK with 250V caps, just thinking about lifespan as I was always taught running a cap very near it's voltage limit will reduce it's life and it's practical voltage rating may creep down over time. Guess it's going to take a while to rack up thousands of hours on these though so probably just need to think about periodic recapping like an amp.

It's the physical height that's the issue with 400/450V ones, the backplate won't go on. Had I thought it through a bit more I would have used a 1590c instead for more vertical room, but my 1590BBs are drilled now.

Thanks for the feedback, used to fix welders so no stranger to HV but confirmation from the designer will always make feel better about flicking the power switch on...
 
bobbass4k said:
Yeah the regulated output is what made me OK with 250V caps, just thinking about lifespan as I was always taught running a cap very near it's voltage limit will reduce it's life and it's practical voltage rating may creep down over time. Guess it's going to take a while to rack up thousands of hours on these though so probably just need to think about periodic recapping like an amp.

It's the physical height that's the issue with 400/450V ones, the backplate won't go on. Had I thought it through a bit more I would have used a 1590c instead for more vertical room, but my 1590BBs are drilled now.

Thanks for the feedback, used to fix welders so no stranger to HV but confirmation from the designer will always make feel better about flicking the power switch on...
Click to expand...
And that is an issue, with 125B and 1590XX the taller caps fit fine, but in 1590BB builds they're not as deep so you would have to lay the caps down on the board, which there unfortunately isn't always room to do. One thing I've done a couple times is mount the cap on the opposite side of the board laying down, then cover the exposed pads with a non-conductive epoxy (or hot glue if you want it removable) for safety.
 
vigilante398 said:
And that is an issue, with 125B and 1590XX the taller caps fit fine, but in 1590BB builds they're not as deep so you would have to lay the caps down on the board, which there unfortunately isn't always room to do. One thing I've done a couple times is mount the cap on the opposite side of the board laying down, then cover the exposed pads with a non-conductive epoxy (or hot glue if you want it removable) for safety.
Click to expand...

Managed to get some 400V Wurth ones at 14mm high which might be a little snug but should work, and some 1.5A Inductors so should be all set now. I'll have to drill my own enclosures anyway so any future C2C builds I do will probably go in a 1590C which is much deeper.
 
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