Power Supply Capacitor

**Boyan Silyavski** · 24-06-2016

A piece of advice about capacitors:

Don't buy a capacitor from non reputable seller, especially ebay. Too many reasons to explain here but in short : China, not genuine, quality, NOS etc.

Buy from Mouser or RS online, i don't know about Rapid online, but i assume as Clive pointed you there it should be good. Buy a brand capacitor- Panasonic,etc. Look for rating 85C or even better 105C rated

Plus i wouldn't save a dollar from a capacitor. A good normal one 85C is rated 2000-3000h at the temperature rating. A better one exact value, not a stack of cheaper smaller ones, that is meant especially for computer and other power supplies could be rated 105C and 20 000h . So its up to you if you will save a $ or 2 from your power supply. Questions to ask yourself: how many hours per day the machine will work, how many years you expect it to last, do you have time later to stop production and investigate eventual problems.

If it was me i would buy a single screw terminal can type capacitor, meant to be there, less space, easy to exchange.

**JAZZCNC** · 24-06-2016

Don't get paranoid with Cap quality or go OTT it's not that critial.
Go with 3 x 4700Uf. They are cheaper and easier to find and provide less ripple than one large Cap. Even the cheap Ebay ones are ok provided you size them correctly. Give them plenty of overhead on voltage and you won't have problem.
I've built probably 100 + and just about every one used 3 x 4700 and never had any issues, Zero failure (Unless I cock up polarity.!!) The PSU running my Own machine is nearly 10yrs old and used Cheap Ebay caps, It's still going strong and as runs for 10hrs day most days.

I buy mine from Farnell.

**cropwell** · 25-06-2016

You can buy cheap Chinese capacitors from China, or you can buy expensive Chinese capacitors from RS or Farnell. It is your choice depending on your perception of quality and service.

**magicniner** · 25-06-2016

One large cap just means there is just one large component which, when it fails, will render your PSU broken.
Provided the conductor area of the connecting bus is large and it's length is short there is no reason not to use several smaller caps in parallel, but buy branded quality from a reputable supplier,

- Nick

**cropwell** · 25-06-2016

I am partly retracting my former statement in the light of this article http://www.hardwaresecrets.com/how-t...ic-capacitors/

Rob

**Clive S** · 25-06-2016

Rob at our time of life if they last 10 years it's a bonus

**JAZZCNC** · 26-06-2016

Originally Posted by Clive S

Rob at our time of life if they last 10 years it's a bonus

Ten more yrs.!!! . . . . Now't like being optimistic.

**Boyan Silyavski** · 26-06-2016

Originally Posted by cropwell

You can buy cheap Chinese capacitors from China, or you can buy expensive Chinese capacitors from RS or Farnell. It is your choice depending on your perception of quality and service.

Its absolutely not like you present it.

**cropwell** · 26-06-2016

Originally Posted by Boyan Silyavski

Its absolutely not like you present it.

If you read my previous post, you will see that I have added information to enable a buyer to make an informed choice. Chinese (and Taiwanese) goods are made as cheaply as possible. This affects quality and in some instances safety. Brand forgery is rife. It does not stop major UK suppliers buying them for sale in UK and, for the time being, in Europe. Major suppliers are not immune from fakes creeping into the supply chain.

I have seen many instances of failed power supplies, with capacitors bulging with internal gassing, on the brink of spectacular failure. These are not always Chinese components.

Japanese capacitors are generally a better quality product, but to me it is a price based decision. I agree with Jazz, that in most instances where a capacitor is not stressed, it will do the job for a reasonable service life, wherever it was born.

Rob