Panasonic EE series caps as PS filter caps?

[schoolie]

Hello all,

Too many choices and too little space. I'd like to use these panasonic EE series radial caps ( 2x100uF@350V and 2x47uF@350V) in the first two stages of a 5f6a circuit. Does anybody have experience with these? They are so small compared with typical axial ecaps that they make me nervous. Could you look over these specs and let me know if there is any issue with using these in a 5f6a? Does the DC leakage spec have any bearing on using these caps in series? It seems higher than other ecaps. Would I be better off with the snap-in TS-ED caps which seem to have low ESR and leakage, but rated lifetime is lower?

Specs on 100uF model (EEU-EE2V101):
--------------------------
Temperature: -25 to 105C
Lifetime: 10000h
DF @120Hz: 0.2 (~2.65 Ohms)
Max Ripple @120hz: 640mA
DC Leakage: 2110 uA (<= 0.06CV + 10uA) Seems high?
Lead spacing: 7.5mm

Thank you! Sorry, this might be the wrong forum for this post.

[Steve Conner]

Nothing to worry about, I guess. Modern electrolytics are just smaller. I like to use the 400 or 450V ones, as running them below their rated voltage can extend the life, and they don't look nearly so small and pathetic.

Balancing resistors are always recommended when using caps in series. They mean that you don't have to worry about the DC leakage.

[schoolie]

Thank you, Steve! I agree I should probably up the voltage rating from 350V. I'm designing for a maximum of 575V, so 350V should be OK, if the caps are well matched in capacitance and leakage. I guess rated DC leakage is only a big deal for coupling/decoupling applications?...but 2mA seems huge. I think these EE caps are for lighting ballasts, so the max ripple current is rated high for high frequencies, but nothing stellar at 120Hz.

Update: Been searching through Mouser and the TS-ED has the best specs, on paper. For $3.50, these are a great deal. I'll let you know how they work, in practice
http://www.panasonic.com/industrial/..._ed_ts_dne.pdf

[diagrammatiks]

the TS-ED's are great.

[Chuck H]

The Panasonics (that you mention AND the ones that diagrammatiks mentioned) have a good rep on other forums. I've been eyeballing the Nichicon caps. Particularly the PW series. Always used Atoms in the past but they've been causing some problems for me. I'm replacing Atoms with the Nichicons in a customers amp tomorrow. I'm also upping the capacitance so it won't be an apples to apples comparison though.

[diagrammatiks]

unfortunately, nichicon doesn't make a specialized audio use axial leaded capacitor anymore.

The TVX is decent but nothing special.

the LKX snap in/clamp mounts are great though.

[Chuck H]

I don't mind adapting to radial leads because I build my own designs. Panasonic or Nichicon, you can't go wrong and it'll cost you a third of what Atoms cost. Bah on the TVX series. Nichicon has great tech into their product. But they also sell to a market that want's to save a nickle by using the TVX, so they exist for that reason. Check out the PW's... No kidding. Not axial lead though.

[exclamationmark]

I've used 450v Nichicon's before to good effect, though they've only been sitting in my amp for roughly a year. I don't recall the exact series, but they had some insane lifetime figures at 105c. The ESR/leakage was so-so, but I bypass all my filter/decoupling caps anyway. The things are minuscule compared to the caps you traditionally find in axial form.

[R.G.]

The technology that's poured into electrolytic caps over the last half-century (i.e., since the 60s) has improved the animal by leaps and bounds. The volumetric efficiency (i.e. how small it is) is enormously better, the electrolytes are more stable, the lifetime is longer, the thermal efficiency - getting the heat out so it doesn't cook the cap - is better.

In particular, the caps rated for rectified-240Vac and doubled-120Vac voltages in the 350-450V area has been improved massively, because of the critical reliance on switching power supplies for rectifying the AC power line. This is one sweet spot for making money on caps, and using this fact to piggyback upon the industry is a great way to make/repair tube amps.

As a result, snap-in electros at about 350-450Vdc are GREAT in terms of size, price, function and life. I heavily recommend using them.

Shoot, I did and do use them.

[Wombaticus]

As a result, snap-in electros at about 350-450Vdc are GREAT in terms of size, price, function and life. I heavily recommend using them.

Shoot, I did and do use them.

Can you recommend a base or mounting system for these that is suitable for use with DIY turretboard or Garolite/eyelet construction? I love the idea of being able to swap caps just with a twist and a pull. Mounting normal radials upright is very space efficient, but represents something of a service headache.

[Chuck H]

I'll be putting radials into an amp that has axial leads in it now. I'll probably just lay them down and shrink tube the lead I pull around the other side. Then I'll zip tie it in place so it "wants" to stay put where the old radial cap was. The caps I'm using today are long thin ones intended to use a small footprint. If I were designing from scratch in an eyelet board amp I would get caps made to take up less vertical space and place the eyelets a little outside the case footprint. Or maybe even off board on chassis mounted terminal strips.

[pdf64]

Regards the voltage rating of series caps, I remember reading somewhere that a de-rating factor should be used, eg if the max possible (unloaded, high line) VB+ was 500, 2 x 250V would be insufficient, something like 350V types were needed.
But I can't remember what the reasoning was.
Maybe it was the tolerance on the cap value, such that if the caps were at either end of the tolerance range, the effect of the capacitive potential divider may overcome the balancing resistors.
Can anyone enlighten; is this a real world consideration?
Pete.

[R.G.]

Can you recommend a base or mounting system for these that is suitable for use with DIY turretboard or Garolite/eyelet construction? I love the idea of being able to swap caps just with a twist and a pull. Mounting normal radials upright is very space efficient, but represents something of a service headache.

Well, "snap in" isn't what it sounds like. It does not imply "snap-out" which is what it kind of sounds like. The leads are springy, and formed so they hold the cap into PCB for soldering. But they're solder-in, intended for PCB.

I heavily recommend making a minimal PCB to mount them. This takes the cylindrical caps and forms a number of them into a group which is roughly rectangular. Then the mounting can be the PCB or a strap over all of them. The PCB could be just copper clad with pads and holes cut into it, then wired, but why not just run the copper to wire holes? I can take a couple of pictures, I guess. The real trick would be to make up a row of these caps soldered into a PCB strip, all of them lying on their sides. If the solder side of the PCB is exposed, then yes, you could unsolder the leads and snap them out without un-building the whole affair.
Chuck H

I'll probably just lay them down and shrink tube the lead I pull around the other side. Then I'll zip tie it in place so it "wants" to stay put where the old radial cap was. The caps I'm using today are long thin ones intended to use a small footprint. If I were designing from scratch in an eyelet board amp I would get caps made to take up less vertical space and place the eyelets a little outside the case footprint. Or maybe even off board on chassis mounted terminal strips.

As I say, consider a minimal strip of PCB material to hold the pins. It makes other things much easier. A die-hard approach would be to take bare FR4, drill holes for the leads, put eyelets in the holes and run wires, but that seems like such a bit of retro-sophistry to me.

Regards the voltage rating of series caps, I remember reading somewhere that a de-rating factor should be used, eg if the max possible (unloaded, high line) VB+ was 500, 2 x 250V would be insufficient, something like 350V types were needed.
But I can't remember what the reasoning was.
Maybe it was the tolerance on the cap value, such that if the caps were at either end of the tolerance range, the effect of the capacitive potential divider may overcome the balancing resistors.
Can anyone enlighten; is this a real world consideration?

The reasoning is that two caps in series may not share the voltage equally, so one get more and one less than half.

If you think about it, what makes the DC voltage on two caps in series share is equal DC leakage resistances. This is something that manufacturers do not spec other than "greater than". As a practical matter, using about 1/4W of external bleeder resistor in parallel with each one will force the voltage to share much more accurately than the unknown and possibly unknowable (with aging) leakage resistances. The bleeders are a good idea for safety too.

The value of the capacitances has little to do with this, except for transients. At power up, the voltage rises on each cap in the inverse of the capacitive ratio. Big caps eat a lot of charge and the bigger cap will have smaller voltage across it until the leakages pull things down to the DC levels. If one cap was (for an out-there example) 100uF and the other only 50uF, then at power on (and off!) the voltage in the 50uF cap would rise and fall twice as fast as the voltage on the 100uF. This is transient. It's not a real problem if you have maybe 10-20% more raw voltage rating than static DC, and divider/bleeder resistors to force sharing.

By the way, this same thing happens in series diodes. For series diodes to hold high voltages, the DC and transients divide by the leakages and capcitances. Best to force sharing with external parts, as this allows you to work closer to the diodes' "edges".

[Chuck H]

Chuck H

As I say, consider a minimal strip of PCB material to hold the pins. It makes other things much easier. A die-hard approach would be to take bare FR4, drill holes for the leads, put eyelets in the holes and run wires, but that seems like such a bit of retro-sophistry to me.

I have been considering that route too. It would be easy enough to just do it on a piece of FR4 perf board you can get in any catalog or at the corner Rat Shack. Then I'd have nice neat terminals to connect to and I could just fly leads to the main board. In my head this or any way I mentioned seems to work fine. The approaches I mentioned appeal to me because I can just drill and punch my boards as usual. But I haven't put any of it into practice yet so I may yet learn any pitfalls the hard way.

[schoolie]

Does the magnitude of the DC leakage affect the performance of caps as power supply filters? The rated DC leakage seem to vary from a few hundred uA to a few mA. I guess I wonder if this characteristic is important.

Thanks!