Just follow the procedure, it is correct as written.
Ignore people who assert that 0.004 (four one-thousandths) equals 4 percent.
Ignore people who assert that 0.004 (four one-thousandths) equals 4 percent.
Mark.. I didn't say that 0.004 equal 4%...
Assuming the total DC R of the filter is 0.1R, which it is likely to be without connections or so
i current through the filter, feeding whatever device you plug it into
Alice = Vin
Bob = Vin-Vout
Bob/Alice = (Vin-Vout)/Vin = 1- Vout/Vin = Ri / Vin = 0.1 x i / Vin = Carol
Carol < 0.004 => Small Carol, 2 filters will work
means
0.1 x i / Vin < 0.004
i <0.04 Vin
Hence i < 4% Vin
Assuming the total DC R of the filter is 0.1R, which it is likely to be without connections or so
i current through the filter, feeding whatever device you plug it into
Alice = Vin
Bob = Vin-Vout
Bob/Alice = (Vin-Vout)/Vin = 1- Vout/Vin = Ri / Vin = 0.1 x i / Vin = Carol
Carol < 0.004 => Small Carol, 2 filters will work
means
0.1 x i / Vin < 0.004
i <0.04 Vin
Hence i < 4% Vin
Welcome to the Big Boy world where these kinds of things happen a lot. Luckily you've got (a) the search engine at octopart.com ; (b) two other part numbers you can look up ; (c) the required capacitance, voltage, lead spacing, diameter, length, and ESR ... so you can evaluate whether substitutes you find online, are acceptable.
There are still some of the United Chemicon version still in stock, but not many. I grabbed 8 pcs. 661-EKYA500E471MJ25S
I cleaned out parts express a few weeks ago to use them to supply the kits I'm putting together for the store. No one else seems to actually carry the Kemets right right now - a quick look at octopart will show you this. Sorry about that, but the good news is that in the meantime really look for Low ESR caps that fit the spec of the board - meaning lead spacing and length. After consulting with Mark the caps for the kit, he recommended the Kemets in the original BOM as they consistently measure out well as do the Panasonic FM/FR series (which apparently are the same thing under the sleeve so you can use either). The top pick is still the Nichicon 647-UHW1H471MPD. I have some of all 3 of these, and will be doing some tests when I get the run of boards I had fabbed, which should be in this week. I'll post my results shortly.
--Tom
I have two I could send you in a letter, which would not be too much for shipping. PM me.
Riki
@Monk55 , is that little board with the adjustable pot for the LED ?
If so where can I get them ?
If so where can I get them ?
The circuit board and the Parts List components of PO89ZB are designed for a maximum of 3 amperes DC current. There is silkscreen text on the top surface of the board which warns you: 48V MAX 3A MAX .
Don't put more than 3 amperes through a PO89ZB, it simply isn't safe.
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Attachments
Great little board. I've used a few of them in various projects like the Whammy. Note that making them yourself on a breadboard is not too difficult, just check out the schematic and you'll see. Its a pot, resistor, diode and small cap used to limit the current to the LED (which also controls its brightness) and also a cap to keep the voltage steady so it doesn't flicker.
--Tom