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184 Time mark Gen. Needs 2 filter caps?

Geoffrey Thomas
 

Hi all,

[Have a read of the bottom of pages 24-26 of this excellent TI article :

http://www.ti.com/lit/an/slva059a/slva059a.pdf

The bottom of page 25 gives a reason for using 2 caps in parallel.]

Unfortunately that link no longer works,(I originally posted it on another group in 2013) but here is an excerpt posted in a reply:

"“ESL can be a problem by causing ringing in the low megahertz region but can be controlled by choosing low ESL capacitors, limiting lead length (PCB and capacitor), and replacing one large device with several smaller ones connected in parallel.”

I'm looking to see if I downloaded a copy.
Geoff.

On 06/03/2020 21:54, david via Groups.Io wrote:
I have no idea what the specs are on these old caps, The serial no. on this unit is 000287, date on PCB is 1965. The schematic shows 125V RMS @ 0.125A across secondary winding of transformer, and 175V measured across 2x40uF Cap. I don't have the knowledge to calculate the ripple current. I don't know what it could be. I think any 82uf x 250V cap is o.k. What is the reason they used a 2x40uF cap?

Dave Hills
 

Any good quality electrolytic 82uF to 100uF, 250v should work just fine. Low ESR isn't
needed here. Likely they used two in parallel because it was cheaper to use a part
already in use elsewhere than to add another p/n to purchase and inventory.

Dave


On 06/03/2020 21:54, david via Groups.Io wrote:
I have no idea what the specs are on these old caps, The serial no. on this
unit is 000287, date on PCB is 1965. The schematic shows 125V RMS @ 0.125A
across secondary winding of transformer, and 175V measured across 2x40uF Cap.
I don't have the knowledge to calculate the ripple current. I don't know what
it could be. I think any 82uf x 250V cap is o.k. What is the reason they used
a 2x40uF cap?