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novice questions - orienting components

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gliptitude

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i'm an electronics novice. i am pretty far along though in a guitar stompbox project, using proven schematics and parts lists, and i have already asked lots of questions in other forums.

:idea: i want to correctly orient my components but i don't have a meter. i think the only components left to figure out are:

:shock: one electrolytic capacitor(47uF) and :?:

:shock: two npn transistors (i think 3904 and 4401). :?:

i read that electrolytic capacitors normally have the negative lead marked, but mine does not. i have two different brands of this 47uF (neither marked + or -) but one of these, which has a lead going in one end and out the other, has what kind of look like arrows going in one direction. one lead is longer than the other.

as for the transistors, they are very small with three prongs. all i know is that it is important to orient them correctly. the three prongs are pretty much all in a row, but it kind of looks like the center one is intended to go in a certain direction (away from the flat side of the cap, towards the curved side).

:shock: i read that resistors are nonpolar and, since trimpots are basically variable resistors, i am assuming that they can go in either direction (so long as the center lead is properly distinguished). is this right? :?:

thanks for your help.
 
The electrolytic capacitor will have arrows on the negative side. The long lead is on the positive side. It is a good idea to look up the data sheet for To-92 transistors because there is no standard for the connections. You can use an ohmmeter to determine which is base, collector or emiter. For an NPN, with the positive lead on the base (on some ohmmeters the black lead is positive) you will measure a low resistance to the collector and emitter. For a PNP, reverse the probes.

You are correct, the potentiometer has no polarity.
 
Russlk said:
You are correct, the potentiometer has no polarity.

Correction- if the potentiometer is LINEAR, it has no polarity to worry about. If it's an audio taper, which seems plausible since it's an audio amp, it's got a specific orientation. Unfortunately I don't know how to identify the direction. If you get it wrong, it'll just cover most of the whole volume scale over the first 1/4 turn and then turning it the rest of the way doesn't give it much more. Shouldn't release magic smoke or anything.
 
You are right, Oznog, but trimpots are nearly always linear ( I never saw one that wasn't). A volume control always turns clockwise to increase volume, so the low end is easy to find.
 
ok, i think i am on track now. one more thing to make sure

i thought i wired up my box correctly but i don't have a guitar handy to test it. however, the LED i have wired in, (according to the instructions and diagrams), does NOT light up. i know the battery is good and i know the LED is good.

i'm looking into a number of things and maybe will contact the author of the LED bypass diagram i used, but i want to make sure i'm wiring the trimpots correctly.

:shock: the diagram pictures show the center lead of the trimpot connected (only) to (a specific) outer lead of the same trimpot. so i did this manually with wire. is this correct? :shock:

thanks for all this info. :eek:
 
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