Panasonic EE series caps as PS filter caps?

[KevinOConnor]

Hi Guys

Electrolytic capacitors are designed to be used at their rated voltage - that's why it is called "working" voltage.

When the cap is manufactured, the dielectric is formed by the application of voltage. To keep the cap healthy and long-lived it must have regular application of voltage. This tells you immediately that having a collection of amps that are rarely used is bad for the caps, and they will be temperamental once you actually pull the amp out andplay it.

Note also that there is no point in derating the voltage, or using the cap at a lower voltage than its rating for 'safety". The cap will reform itself to the voltage applied to it, so your 350V cap becomes a 250V cap if it only ever sees 250V.

Panasonic, Nichicon, United Chemicon, Cornell-Dublier, Epcios, TDK and others all have various ranges of caps and it is important not to buy the low-end stuff that is typically just 1,000-hour rated. if you are only building one amp, get 10,000-hour caps as these are only marginally more expensive than shorter-life caps. Note also that the life rating is at maximum temperature. For each 10C below the rating that cap is experiencing, its life time doubles.

Radial-lead caps usually have twice the ripple current rating of a similar axial-lead, so why waste money on the latter? besides, the radial is mechanically superior and thus less likely to go open and require replacement. All the layouts for amp projects in TUTs 3&5 use radial-lead caps.

In many amps there is absolutely no need to series-connect the first filter. 500V and higher electrolytic are available and you should check the voltage in your amp to see if single caps might be used there.

Have fun

[KevinOConnor]

Hey

Also, for mounting snap-mount caps: use perf-board drilled on a 0.1" spacing and slightly enlarge the holes where the cap terminals will go through. use buss wire on the other side to connect to eyelets, turrets, or other components. Similarly, you can use bare sheet material (phenolic, epoxy-glass, etc) and make connections as described, just rill the holes as needed.

The snap-in cap should literally snap into its lead holes as this provides a mechanical hold in addition to the electrical connection if on a PCB.

Splay the leads out on radial caps. They do not need silicone or other gopp to hold them - just solder the leads well.

Have fun

[Gaz]

Hey

Also, for mounting snap-mount caps: use perf-board drilled on a 0.1" spacing and slightly enlarge the holes where the cap terminals will go through. use buss wire on the other side to connect to eyelets, turrets, or other components. Similarly, you can use bare sheet material (phenolic, epoxy-glass, etc) and make connections as described, just rill the holes as needed.

The snap-in cap should literally snap into its lead holes as this provides a mechanical hold in addition to the electrical connection if on a PCB.

Splay the leads out on radial caps. They do not need silicone or other gopp to hold them - just solder the leads well.

Have fun

Kevin,

You are one of my personal amp guru heroes and I own all your books, but I must say from experience that mounting radial caps as you suggest with the leads "splayed out" is not reliable, even with silicone. I loved doing layouts with that method, but have had a few leads snap off that way. This wasn't even at the bend, but where the lead enters the body. Even most of the small radials are too heavy. The proper way (as seen in military soldering guides) to mount radials is like this, but it complicates the layout some. The zip ties are totally unnecessary because the caps are siliconed. Must just be for looks.

[KevinOConnor]

Hi Gaz

Thanks you for your kind support!

Yes, tying the body of the caps down with zip ties is good to do especially for a combo amp. I would suspect the broken leads you encountered were the result of over stressing the leads rather than from mere vibration. In turret construction, over-stressing of all component leads is very easy, where for eyelet construction it is not. So, tying the cap to the board and making wire connections and/or low-stress connections will improve things compared to what happened before.

In my experience, and for anyone who has given me feedback about the TUT3 and TUT5 projects, there is no inherent problem with the splayed leads when using radials on eyelet boards. In those projects, the caps stand up and are supported just by the leads. A 22uF-450V radial weighs about 5.5 grams so it is not going to stress the leads when supported this way. I weighed a group of ten, which was 55g or 1.9oz.

I prefer not to use silicone to support larger components as this makes repairs a bit messy and with glass-epoxy component carriers, the silicone does not actually adhere all that well. I've seen caps in PVs be entirely free of their goop, then the welded lead breaks and there is no filtering. In my amps that use large polypropylene filter caps, I use two tie-wraps per cap.

Have fun

[Ken Moon]

Here is another way to mount radial caps (Nichicon PW series in this case):

[Ken Moon]

I posted this in the wrong place, so I'll try again

Here is another way to mount the PWs (I know it looks like some leads are shorted to each other from this pic, but they are separated vertically by over 1/2", so no worries, but it's easy to put on some shrink tubing or teflon tubing if this is a concern:

[Chuck H]

Here's how I've done it to save space. If you like all your caps at one end of the board or if you have a bunch of caps (I had fourteen in one design) this is a good way to do it. Just a modification on what's already been shown. (didn't have a pic so I just drew it out on paint)

[SoulFetish]

Hi Guys

Electrolytic capacitors are designed to be used at their rated voltage - that's why it is called "working" voltage.

When the cap is manufactured, the dielectric is formed by the application of voltage. To keep the cap healthy and long-lived it must have regular application of voltage. This tells you immediately that having a collection of amps that are rarely used is bad for the caps, and they will be temperamental once you actually pull the amp out andplay it.

Note also that there is no point in derating the voltage, or using the cap at a lower voltage than its rating for 'safety". The cap will reform itself to the voltage applied to it, so your 350V cap becomes a 250V cap if it only ever sees 250V.

(sigh...) NO, NO, NO, NO!!! Dude, this is not correct at all. The voltage rating of the capacitor is the maximum working voltage within the specified working temperature which is specified in the data sheet. There are many applications where derating the voltage is not only beneficial, but advised. For instance, when used in high ambient operating temperatures, an electrolytic cap can perform much more reliable when derating the voltage. The ambient temperature, and internal operating temperature(usually a function of ripple current) have the most significant impact on capacitor life. Using electrolytic capacitors under their rated voltage will ABSOLUTELY lengthen capacitor life, but it is not as significant as temperature.
I don't have time to get into in right now, but the statement "The cap will reform itself to the voltage applied to it, so your 350V cap becomes a 250V cap if it only ever sees 250V" is just not what happens at all.
...I'm not even sure how to tackle this statement exactly. I don't want to sound like I'm being a dick though, but where did you get the idea that happened with the applied voltage to the cap? It is not the case, suffice to say.

Edit: after thinking about it, maybe I misunderstand what you mean about the a 350V cap becoming 250V. Maybe you dont mean what I though you meant. So feel free to clarify.

[SoulFetish]

Note also that the life rating is at maximum temperature. For each 10C below the rating that cap is experiencing, its life time doubles.

This is true, and is good advice, Kevin.
If I may, I would add that the temperature threshold has a minimum as well. The electrolyte in aluminum caps operates like shit at low temperatures and has stability issues

[Chuck H]

Well, I can't attest to the actual mechanisms involved but I can say that when some nerds "re form" old caps (a practice I don't endorse) the common method involves bringing it slowly to it's full rated voltage at some low current and holding it there for a time. Usually in a heated environment like a shoe box with a heating pad stuffed inside or something like that. Now, this is done by guys that would have developed this method ad hoc, without the benefit of a technically derived course of action. My point being that to get the caps back to their working voltage it was "discovered" by an independent demographic that they must be charged to that voltage. This somewhat backs some of what Kevin was saying about working voltage and rated voltage WRT the electrolyte behavior... I think.

Just sharing an observation.

[Jazz P Bass]

If interested, an E Cap application guide from the horses mouth (Cornell Dubler).

AEappGUIDE.pdf

And Rubicon:

cautionalumi_eng.pdf

[SoulFetish]

Well, I can't attest to the actual mechanisms involved but I can say that when some nerds "re form" old caps (a practice I don't endorse) the common method involves bringing it slowly to it's full rated voltage at some low current and holding it there for a time. Usually in a heated environment like a shoe box with a heating pad stuffed inside or something like that. Now, this is done by guys that would have developed this method ad hoc, without the benefit of a technically derived course of action. My point being that to get the caps back to their working voltage it was "discovered" by an independent demographic that they must be charged to that voltage. This somewhat backs some of what Kevin was saying about working voltage and rated voltage WRT the electrolyte behavior... I think.

Just sharing an observation.

If we are talking about rehabilitating old Electrolytics of even the process of forming the capacitor, it's a very different thing than nominal operating conditions.

But I avoid using electrolytics unless I absolutely have to. No Electrolytics in my amp

[Chuck H]

If we are talking about rehabilitating old Electrolytics of even the process of forming the capacitor, it's a very different thing than nominal operating conditions.

But I avoid using electrolytics unless I absolutely have to. No Electrolytics in my amp

I considered trying that. Haven't yet.

There are certainly mediocre electro caps offered that can't compete with what was a common product in the golden age, but there are also some VERY good caps available with excellent specs for life hours and temp for only a couple of bucks more. As a home builder it's easy to avoid the crummy caps that typically go into production amps. I don't mind using GOOD aluminum electrolytics. They're comparatively small, affordable and should last fifteen years. Any amp would probably need some work at that point anyhow. Yet...

Whenever it comes time to recap one of these amps I reconsider permanent caps