Mouser ordering question

[newbie builder]

I need a 3.3uf Non polarized capacitor for a pedal, and i'm ordering the  parts from small bear. Does:    

Capacitor, Electrolytic, Axial 16 V

Mean that it is polarized? If so, can i just use two and link together the negatives do I have one non-polarized capactitor?
Thanks--

[rockgardenlove]

^Nope, that won't work.  They are polarized.  In most cases a polarized cap will work fine though, what circuit are you building?

[newbie builder]

AMZ Mini Boost.

[R.G.]

Mean that it is polarized?

Every electrolytic capacitor is polarized unless it explicitly and clearly says otherwise. The notation may be "bipolar" or "non-polar".

If so, can i just use two and link together the negatives do I have one non-polarized capactitor?

Yes, you can. You can make a quick and dirty NP cap by tying together the negatives of two equal-sized polar caps.

In the series-NP connection, the capacitance value is funny. Normally caps in series are a smaller capacitance than either cap by itself. If you had two 3.3uF polyester caps, then the expected value for two of them in series is 1.65uF. However, electrolytic caps actually conduct in the reverse direction, so two 3.3uF polarized aluminum electrolytic caps act like they each have a diode in parallel with them that conducts when the voltage is backwards for that one cap. So two 3.3uF caps hooked up as series non polar (i.e. negative to negative) look like a single 3.3uF NP cap.

... except for tiny region near zero volts where they withstand a tiny reverse voltage, so they look like 1.65uF there...

ACK~!!!

But yes, you can use two polarized electros in series negative to negative to do the job.

NB: Mouser has NP caps...

[newbie builder]

Thanks! I was going to order from mouser, but instead I think I'm going with Small bear so if I can get everything there it makes life easier, I have no problem with connecting the negative leads of two capacitors. Another obviously newbie question is when looking at the mosfet boost schematic calls for a "9.1v zener" Whats that?
Thanks!

[R.G.]

Zener diodes are diodes that are used to regulate or clamp voltages.

When the voltage across a zener diode is the normal way, it conducts like a normal diode. The "normal way" is positive on anode/arrow, negative on cathode/bar.

When the voltage is backwards (i.e. positive on cathode/bar and negative on anode/arrow) the diode blocks current until the voltage gets to its rated voltage, at which point it starts conducting. The voltage in reverse conduction stays very nearly the rated voltage as current increases.

The power it dissipates in reverse conduction is the product of its rated voltage and the current it carries, so it will regulate voltage to its rated voltage from very low reverse currents up until the product of its reverse current and voltage equal its power rating, at which point it burns out.

Zeners have type numbers, like 1N757, etc. But there are zillions of zener series, and they are all similar, so people usually just say things like "9.1V zener" and let you pick whichever type number you like. The 1N757A happens to be a suitable 9.1V zener for you. But there are other type nubmers, such as the 1N5239B, which are also rated at 9.1V and 1/2W.

In this case, the zener diode is being used to protect the gate of a MOSFET from static electricity. Any zener diode rated for 9.1V will do the job, but you want a low power rated one because low power is fine in this application and low power ones are cheaper.

[newbie builder]

Thanks very much for the replies. This place has really taught me a lot, and I know I would not be able comprehend the simplest of DIY projects if it weren't for the reading I've done here.

[newbie builder]

Another question-this time about pots. What is a "100k A" pot vs. a "100k B" pot?

[R.G.]

Thanks very much for the replies. This place has really taught me a lot, and I know I would not be able comprehend the simplest of DIY projects if it weren't for the reading I've done here.

Do yourself a favor. Go to GEO - http://www.geofex.com - and read it. All of it. Some of it won't make sense, but some of it will not only answer questions you don't know you have yet, but spark a whole new level of questions.

Another question-this time about pots. What is a "100k A" pot vs. a "100k B" pot?

At GEO, read "The Secret Life of Pots".

The short answer is that the resistance traversed per degree of rotation on a pot is not always a constant. For the A taper(that's 100K A), the resistance traversed per degree varies as the exponent of the rotation. The resistance traversed increases very little at first, then very quickly. I happens that this matches the human ear's logarithmica sensitivity to loudness, so this taper causes a linear increase of apparent volume per degree of rotation, and it's use for volume controls.

For other things, you want a linear amount of resistance traversed per mechanical degree; that's the "B" taper. B tapers can make the voltage at a wiper increase linearly with each degree of rotation.

There are many other tapers.

Read "The Secret Life of Pots".

[newbie builder]

I had been meaning to read geofx, and read a lot of it last night, and am very glad I did. It answered the questions I had, and even though I couldn't comprehend all of what I read now, I know it was a good thing to do.
Thanks-
newbie

[newbie builder]

On a lot of parts I'm trying to order from mouser they say: RoHS: non-compliant/CONTAINS Pb

Does that matter at all?

[newbie builder]

Bump   

[John Lyons]

RoHS is a new classification for parts with certain metals in them that may or may not be "banned" or resitricted in certain countries, areas etc etc.  This has nothing to do with if the part will work or specification...  This is an environmental issue/law...

[newbie builder]

Thanks! I was also wondering if somebody has the mouser # for DPDT switches and for mono/stereo jacks. Thanks--

[smallbearelec]

I need a 3.3uf Non polarized capacitor for a pedal   

I do carry these...there's a line item in the Electrolytics section. Click the item title and you'll find a drop-down for picking the 3.3 mf.

For the Zener, I have the 1N4739A. Note R. G.'s comment; the power rating doesn't matter.

the mouser # for DPDT switches and for mono/stereo jacks. Thanks--

I will have Alpha DPDT stomps back in stock in the next couple of days; they are on on a plane now. Mouser is a little expensive on the Switchcraft jacks commonly used here. I am happy to say that the heavy demand for these has allowed me to buy enough to offer better pricing than you will find at much larger shops.

Sorry I can't spend as much time here as I would like to, but you can always e-mail me if you have questions about shopping.

Regards
Steve Daniels

[newbie builder]

Thanks Steve-
I think I'll soon be ordering lots of jacks, pots, enclousers, and stomp switches from smallbear