IC type numbers and cap power rating

Ansur · Post by **Ansur** » 14 Oct 2012, 12:53

Hi guys,

I've been wanting to start building some pedals for some time now, and I finally decided Madbean's Current Lover seems like a great starting point.
Just to say, I've only done one project before, which was a VHR Hiwatt. That actually worked out really well.

The nice thing with the Hiwatt was that I could just order all parts, and it was 'just' a matter of putting it together.

Now, having to order each individual part - which is a first time for me - I'm questioning some things since I only have a passing knowledge on electronics.

For now, two questions stand out:
- on ICs: when I check a shop like Mouser and search for one of the required ICs, the part number almost always has a suffix. Can I ignore and just pick any one out, or what should I be looking for to determine whether a certain IC is right for a stompbox?
E.g. results for NE5532 (which I've been given to understand is a better choice than the JRC4558 listed in the BOM for this flanger)
- on capacitors: here, it seems those of the type RN55 are a good choice. In general, I noticed their power rating is a bit lower compared to other capacitors. E.g. RN55 vs. another type. Is this power rating something to consider for audio applications or not? Pretty sure I saw builds with both these types, some I'm guessing it's safe, but it would be grand to have a confirmation on this.

Thanks in advance already, hope you guys'll bear with me during my first posts, as they might contain some really basic questions

Ansur · Post by **Ansur** » 17 Oct 2012, 06:00

Alright, so when I look at the data sheets of some of these ICs, I'd say that I can use any of them. Still, is there a preference or a way to distinguish some of these for my use: inside a stompbox?

As for the capacitors, I'm afraid I didn't really find more information. Just that the RN60s would work, but with the RN55s there's still the power rating question I have. Some guidance here would be very much appreciated.

Dirk_Hendrik · Post by **Dirk_Hendrik** » 17 Oct 2012, 08:02

When you look at the datasheet pretty often that will tell you what the suffix means. In many cases that is the package in which the chip is cased like plastic, ceramic or metal can.

When looking at suppliers sites it may be you find additional suffixes which denote (from the chip manufacturer) the larger packaging in which the chip is supplied. If the supplier puts an item online available in a quantity of 1 and the sufffix tells you the chip is packaged in reels of 1500 chances are good the supplier copied and pasted the partnumber witchout checking the suffixes.

But in essence, the electrical functionality is the same indeed.

Ansur · Post by **Ansur** » 18 Oct 2012, 10:34

Ah, I didn't notice that. That's one worry down, thanks!

As for the Power Rating, that still isn't clear to me.
I read some technical articles but they mainly seemed to talk about Power Rating for AC circuits,I'm still not really sure about how I can deduce the needed Power Rating for a given circuit.

Dirk_Hendrik · Post by **Dirk_Hendrik** » 19 Oct 2012, 20:10

That's Ohms law.
If you know the voltage difference between the 2 nodes where the resistor is connected you can calculate the current. Then, the power rating is P(ower)=I^2*R. (where I^2 is square or I*I). For resistors there's no difference between AC or DC.

Except for resistors in the power supply (where there may be a requirement for a larger power factor) or LED resistors usually 1/8W or larger resistors are fine.