How select the Commonly Used Electronic Components

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Leo Hathaway
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How select the Commonly Used Electronic Components

Post by Leo Hathaway » Wed Nov 07, 2018 1:05 am

Daily contact with electronic components is a common practice for engineers, but for beginners, even if they have information about the type of components they need, it is a headache when they browse the merchants to buy them. The datasheet is the same, and there are some additional reference values that differ from the use of different materials. I don't know if it's going to affect the circuit I'm going to use, and it's a waste of time to check and ask with too many qusetions. After all, more than one component is needed.

For example, I need an aluminum electrolytic capacitor in the power filter, decoupling circuit, browsed several websites are similar, opening such a website( enclose one of them: https://www.kynix.com/Product/36.html), what should I look at and focus on?

dyarker
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Re: How select the Commonly Used Electronic Components

Post by dyarker » Wed Nov 07, 2018 7:09 am

The pick of a part usually narrows down to one or two when you "do the numbers".

Following your power supply cap example - You need the minimum voltage the load can run with, and maximum current it will draw. The peak of the maximum rectified voltage minus then minimum the load can use is the supply ripple voltage. The ripple, max current and frequency determine the minimum capacitance needed. The frequency depends on full-wave or half-wave rectification, and 50Hz or 60Hz mains. Pick the next higher standard capacitance, or maybe the one above that. (Going higher reduces ripple further, but makes the current pulses from the mains "nastier".)

For the capacitor voltage rating find the peak rectified, no load. voltage. Pick next higher standard value. Except for temporary breadboards don't go higher. Electrolytics may "deform" if used at too low a voltage (or left on shelf).

You probably do not want SMD (oven flow soldering, maybe machine placement). Radial leads for through-hole, maybe breadboard. Axial for through-hole (but more space on printed circuit), or terminal strip construction.

Low ESR caps "typically" for switching power supplies and class "D" power amplifiers. They'll work here, but are more expensive.

Same for most components. Concept design, math, decide "big" components (like transistors and ICs), math, decide "small" components (resistors, capacitors), math one more time to make sure it works with the all chosen components together.

Cheers,
Dale Y

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MrAl
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Re: How select the Commonly Used Electronic Components

Post by MrAl » Thu Nov 08, 2018 1:06 pm

Leo Hathaway wrote:
Wed Nov 07, 2018 1:05 am
Daily contact with electronic components is a common practice for engineers, but for beginners, even if they have information about the type of components they need, it is a headache when they browse the merchants to buy them. The datasheet is the same, and there are some additional reference values that differ from the use of different materials. I don't know if it's going to affect the circuit I'm going to use, and it's a waste of time to check and ask with too many qusetions. After all, more than one component is needed.

For example, I need an aluminum electrolytic capacitor in the power filter, decoupling circuit, browsed several websites are similar, opening such a website( enclose one of them: https://www.kynix.com/Product/36.html), what should I look at and focus on?
Hello there,

The range of parts and values is hard to comprehend at first. It seems like there is an endless number of parts out there, and that is because THERE IS!

If you are just getting started with electronics then the most common part is the resistor. Here we have several common values like 10 ohms, 22 ohms 47 ohms, 100 ohms, and then repeat after multiplying by 10 which gives us 220, 470, 1000, and then again by 10 to get 2200, 4700, 10k, and then again 22k, 47k, 100k and then again 220k, 470k, 1Meg. I just gave you a list of more common values, although there are some in between there too, but that gets you started in seeing the big picture here.
Now there are different power ratings, we have 1/4 watt and 1/2 watt the most common, and higher wattage ones are for more specific purposes like 1 watt, 2 watts, 5 watts, 10 watts, and higher than that are for VERY specific purposes.
So you see we have some common values and some for specific purposes. That's the way all electronic parts are in general.

There are small capacitors that follow that same basic rule, and small inductors too, but the inductors also have other specs like series resistance that is very important sometimes. Then larger inductors are for very specific purposes too, and have to be specified in a more exact way.

Then we get into the IC chips, which vary all over the place. Common starter chips are the LM358 like you know about already, and then some logic chips like the CMOS series.

What you might want to do is state what area of electronics you are most interested in. For example, power supplies, RF applications, digital logic, microcontrollers, etc. That way we can direct you to the right parts.

In almost all cases though you need resistors. Some values as above in 1/4 and maybe 1/2 watt sizes unless you intend to do SMD work and then you might choose smaller wattage ratings.

In all cases it helps a lot to know your end application as that ultimately is the deciding factor on what actual parts you need to buy. Some people start with a single project and buy the specific parts for that, then go on to buy other parts later. This seems to be a preferred method for a lot of people because they can start to build something right away with less cost right away.
LEDs vs Bulbs, LEDs are winning.

Leo Hathaway
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Re: How select the Commonly Used Electronic Components

Post by Leo Hathaway » Thu Nov 08, 2018 5:57 pm

Thanks a lot for all you guys suggestions, I will continue to look for the better way to improve my ability at this field.

Sincerely,
Leo

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haklesup
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Re: How select the Commonly Used Electronic Components

Post by haklesup » Fri Nov 09, 2018 11:44 am

Capacitors are among the most confusing parts to select because there are many unfamiliar parameters delineating product lines and quality/reliability grades. This as well as similar values and form factors over different construction types (electrolytic vs tantalum for example).

Best place to start is a filter like on Digikey, you can quickly whittle 25000 parts to a few hundred just by selecting key things like value and package footprint/size. From there eliminate the stuff not in stock and those expensive ones with too high tolerance or whatever spec and you could be down to a few tens of choices. At that point they may be equivalent from different brands or you may discover another parameter that is important to you like temperature range, or high reliability. Final selection is usually by price and lead time.

For caps especially, some parameters and grades are more relevant to the high volume manufacturer where pennies do make a difference and reliability calculations are based on these values and researched reliability factors. For us, we can learn to ignore some of this and just get the best quality one based on value, tolerance, temperature and package type needed for a particular application

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Lenp
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Re: How select the Commonly Used Electronic Components

Post by Lenp » Fri Nov 09, 2018 6:25 pm

What I think is most confusing for most is the sea of capacitor types and the best pick for the application. All types have specific attributes but I have not seen a lot of data on specific applications. The vendor's filters help to separate them but picking the right type is a different problem. Maybe data in a chart format would be a big help to newcomers.
Collaborative project maybe?
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)

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