Resistors Questions - Page 1
Forum section: electronics / beginners

author: Savetheday
author_rank: Regular Contributor
timestamp: September 16, 2015, 02:10:57 pm
content: HiI'm working on a project which has a lot of %5 resistors.Right now i don't have those kind of resistors i have only %1 littel bit small resistors.May I use %1 resistors instead of %5 ones? AndHow about using for 2.7 Kohm's %5 resistor, 2,6 Kohms's %1?Thanks,

author: w2aew
author_rank: Super Contributor
timestamp: September 16, 2015, 02:49:15 pm
content: Quote from: Savetheday on September 16, 2015, 02:10:57 pmThe % value is the tolerance - in other words - how close the actual value will be to the marked value. A 5% resistor can be as much as 5% off of the marked value, while a 1% resistor can be off by only 1% at most. So, yes, you can certainly use 1% resistors in any place where a 5% resistor is specified. In the case of the 2.7k 5% resistor, the actual value could be as low as 2.565k (2.7K - 5%). The 2.6k 1% resistor could be as low as 2.574k (2.6k - 1%). Thus, even in the worst case, a 2.6k 1% resistor can be used in place of a 2.7k 5%, since the 2.6k 1% resistor will always fall within the range of where a 2.7k 5% resistor value *could* be.

author: max666
author_rank: Frequent Contributor
timestamp: September 16, 2015, 03:27:24 pm
content: w2aew explained it nicely already.I just want to mention the power rating as well, since I believe you mentioned your resistors are smaller. But most of the time that won't be an issue anyway, and if you do have a resistor that requires a higher than usual power rating then it's often mentioned or fairly obvious.

author: Savetheday
author_rank: Regular Contributor
timestamp: September 19, 2015, 02:26:43 pm
content: QuoteI got it.I have a next question? In my datasheet , i see a capacitor with 33 nF 63/100WV value. What does it mean 63/100WV ?I have blue colored 22n MbE and 3n3 Ceramic capacitors and I measured it with19,88nF and 3,5 nF = 3579 pF. Should i use either one of them or better something als like film capacitor or tantalum? Actually why couldn't we use only one kind of capacitor for example electrolytics.thanks a lot.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 19, 2015, 03:48:32 pm
content: The 63/100 WV making is the maximum specified voltage. Its 63 V (eff) AC or 100 V DC as the maximum working voltage.Caps often have quite large tolerance - so 5% accuracy is allready good for a cap. So the 20 nF for a 22nF nominal cap is nothing unusual. It can be as bad as -50%/+100%.The different capacitor types have different properties - a real capacitor als has loss, leakage, ESR and similar properties. So one can not generally use just one type. Especially electrolytics are far from ideal caps, they have quite some ESR, leakage and loss and usually a fixed polarity. Also the capacitance values are limited for each technology: you hardly find electrolytics below 0.2 µF and film type above 100 µF.So there are cases where you can choose, but often the capacitance dictates to use ceramic caps for the very small ones and electrolytics for the very large ones. If one type comes close to work for most purposes, it's ceramic caps. But this are allready 2 types of ceramic materaial with quite different properties.

author: Savetheday
author_rank: Regular Contributor
timestamp: September 20, 2015, 10:45:06 pm
content: Quote from: Kleinstein on September 19, 2015, 03:48:32 pmCool thanks.I have some kind of ceramic capacitors. They are coded I guess, It looks like this 18p (I measured = 57 pF), 27pk C0B (63 pF), 1p5 (38 pF), 4p7 (43 pF), 20p (55 pF) , S10 K 60 9548 (930 pF), 4n7 (4662 pF), 47p (83 pF), B 103 K SEM (9500 pF) Is there any easyway to read this codes without of checking with capacitor-meter?Where can I find that code list? For example for 18p must be 18x3=54 p for picofarad ?One more question is it possible to use capacitors serie and paralel? I meane for 33nF are we able to add parallel two ceramic capacitors like 22nF+10nF=32nf or serie 80nF + 80nF=40nF? Such as resistors are we able to add two or more series 50 ohms 30+10+10ohms? (It looks a bit dirty but who cares!Thanks

author: Maxlor
author_rank: Frequent Contributor
timestamp: September 21, 2015, 12:24:12 am
content: 18p means 18 picofarad, 4p7 means 4.7 picofarad and so on. The reason you measurements differ by around 35 picofarad is because you didn't subtract the capacitance in your meter and leads. If your meter has a "REL" button, press it before doing the measurement (with the lead tips not touching anything), and the meter will subtract its own capacitance. Otherwise, you'll have to do it manually: read the value that you get without touching anything, then subtract that from your measurements. 35pF is a pretty typical value for a meter's capacitance btw, but it can vary from meter to meter (I've seen >100pF), and may change depending on environmental factors such as humidity.A 3 digit code like 103 usually means: "10", plus 3 zeroes, in pF, so 10000pF.Are you sure the "C0B" isn't actually a "C0G"? That would be a code describing the temperature properties of the cap. More info and a list of such codes can be found on the wikipedia page forceramic capacitors.Connecting caps in parallel is done frequently for a number of reasons, such as increasing the capacitance when you have a standard cap size on your BOM already, or influencing other properties such as ESR. The latter point is also why you sometimes find a 10uF and a 0.1uF cap paralleled.Caps in series are more rare, because why do it when they're physically large devices and you'll end up with half the capacitance? The only reason I can think of off the top of my head is handling voltages above each individual cap's rating.

author: Savetheday
author_rank: Regular Contributor
timestamp: September 21, 2015, 01:45:40 am
content: Quote from: Maxlor on September 21, 2015, 12:24:12 amGreat thanks.QuoteI'm not sure.It could be. They are so small printed I might be wrong.I have MKT capacitors I read it 1n5 M 250 V~ WK0400V~ I think "~" stands for AC.Can we use it like DC?they are a little bit big though.And what about resistors?Is it standard to use series and parallel more then two resistors in a circuit?

author: mariush
author_rank: Super Contributor
timestamp: September 21, 2015, 02:19:17 am
content: Just like capacitors, resistors can be connected in series or parallel for lots of reasons.Resistors are connected in series to reduce the voltage drop on each resistor, therefore reducing the power loss (and by consequence) the heat it produces. With a single resistor, as current flows through it, it warms up and the resistance drifts away from the specified value.As another example of using resistors in series, it's an easy way to tweak/adjust something without resorting to potentiometers. You can put several resistors in series and if you want to change resistance you can just short the terminals of one of the resistors in the series and it's basically gone. Sometimes this method is used when pressing buttons on a front panel, for example a microcontroller constantly reads the voltage coming from front panel, which changes when the resistance changes (due to button shorting a resistor).Resistors are connected in parallel to achieve lower resistances and sometimes as a simple way to get a more "precise" resistor from cheaper parts. For example, you can get 10 resistors of 10 ohm 5% each and when you connect them all in parallel you'll get a 1 ohm resistor that will be closer to 1% than 5%