Pacman wrote: 01 Dec 2024 15:38
The choice of capacitors seems complicated for us non-educated hobbyists, and even buying well known branded capacitors has its challenges :o
If I'm not mistaken for what you and others here are saying: "don't worry about ESR values" (electronic circuits in general) with the exception of power supply capacitor replacements where it gets even more complicated?
It is difficult to generalise such things because every circuit is different with different requirements. Of course if I was building a 555 timer circuit to flash some LEDs, I doubt anyone would really care what the quality of the capacitor is. Though if I put such a thing into production and I wanted it to last as long as possible, then I may spend a little time in choosing a better quality capacitor.
What I suggest is, if you're going to the trouble of looking for a capacitor, you might as well spend a little extra time in looking for one which has a genuine (or best) specification as they are generally much better quality. You generally have to look at datasheets to confirm physical sizes and voltages etc anyway. If they don't mention mA rating then I would just simply avoid that manufacture. If they quote such things, they are generally better than most. Choosing "the best" can take more time. We are not specifically worrying about the ESR as such, we are just being more selective in choosing a part which has proper information listed. If manufacturers don't list information then generally those capacitors are simply garbage should be avoided.
Power supplies and high current circuits generally work better with lower ESR values. A lot of people just go for the cheapest value "which fits" and this can be bad on poor quality caps. You have to imagine a resistor in series with the capacitor. The higher that resistor value, the hotter it gets, and of course heat degrades the life of components. That wasted heat could be better used for improving efficiency and regulation of power supplies and other circuits. If that resistance is too high in whatever circuit it is being used in, it can lead to overheating and they can even explode. I know for a fact some people have been recapping power supplies and selling them with bad quality caps and they have indeed exploded.
It would be like buying a car without enquiring what the MPG is, or the manufacturer simply not listing it. If you don't care about MPG, then everything is probably "fine". A lot of people love to live life in ignorance. But if you do enquire about MPG, and one manufacturer lists 5MPG and the others are all around 40MPG ( assuming the claims are legitimate) then you would naturally go for a 40MPG car.
Some of my audio circuits are using tantalum capacitors, and from what I've heard they can explode badly and people recommend replacing them with electrolytics. Catch 22!
That is probably older advice.
Are tantalums of today better/safer than those in the past, so a new tantalum is still better than an electrolytic replacement for audio?
I haven't tested tantalums for around 20 years. They seem to be "all the rage" back then. I tried one in a power supply circuit once and it exploded. I tried a second one and it also exploded. I wondered if I had it in backwards, so I tried a third one the opposite polarity and that one exploded. I just simply never use them again. I do know a lot of other people have said they have caught fire and exploded and I have personally seen this happen a lot of equipment I have worked on over the years. But I don't really see a need for them anymore anyway.
Audio circuits generally use low values like 22uF. There's a huge range of ceramics which can do that job these days. Of course you need the electrolytic's for the bulk power supply capacitance anyway. But there is certainly no reason to use electrolytics in the audio path anymore.
Of course a lot of my own personal preference is to use better quality parts. Having come from a large company repairing equipment, with manufactures using the cheapest parts, it resulted in a phenomenal amount of repair work over the years. So of course I'm going to be a little bit more biased than people are in general. It's just become a habit for me to chose something better than just "any old part" and calling it job done.