|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
70.197.4.43
There are many 100uf and 10uf caps rated 50v and 63v in a dac with a 12v regulated supply. The most I see without measuring everything is 24v across an op amp. I see no reason to use anything above 25v or maybe 35v. Why would the manufacturer use such high voltage caps?? Is my assumption that 25V is all I need correct? A couple of measurements of cap voltages were way low. Would this be for longer life or maybe they just got a good deal on cheap caps? Thanks, Tweaker
Follow Ups:
I agree with everyone else, but here is one rationale not mentioned: Perhaps there is a voltage surge at start-up, and the voltage ratings of the capacitors were chosen to assure that the capacitors won't blow when the unit is started up from "cold". Since higher voltage capacitors generally (but not always) cost a bit more than lower voltage capacitors, all other things being equal, it is hard to believe that the manufacturer is using those capacitors for no good reason. (However, as Coris mentioned, it is possible that he got a great deal on a bulk buy of caps at a certain voltage that he needed for some other application.) I would not change out those capacitors for lower voltage ones, unless or until I could rule out the start-up question.
It is often more economical for the manufacturer to use a higher voltage cap than it is to stock two different values.
Dark energy? Ridiculous!
We live in an electric universe.
Edits: 06/26/16
Indeed! And more, in this industry is more important what it have to say the financial department, than what and how they do the professional designers of a device...
And so/therefore it were "invented" the tweakers, who in most cases may put back in place the pieces, or what is missing, and eventually add what is needed...
That specified max voltage rating for a cap it is already into a safe working area (for the specified number of working hours, and for the rated temperature), so as it is market on its body by the factory.
A cap rated 12v it can tolerate 16v, but is not recommended to work at that voltage. A 25v cap it tolerate 30v, a 63 it can do 70v and so on. The safest higher voltage a cap is rated for, it is labelled on it, and it can work very well at that max voltage (for the specified number of hours). Exception from this "rule" are the double layers caps, which even are rated for a certain max voltage, and a working temperature, for the specified working hours, it is recommended to be used at the lowest as possible voltage, to increase its life. This is because their quite special construction, enough different that the rest of the common electrolytic capacitors, widely used out there.
In my opinion, the use of two times or more higher rated voltage caps for the in fact working voltage is just stupid design. Well, there is something else when about AC rated voltages, high frequencies, or high voltage circuits. Such areas are not in discussion here, especially your question it is about (DAC device).
The subject here is is about power system filtering caps, and eventual decoupling caps.
The higher the rated voltage for a cap, the bigger its physical dimensions, and wasting of space. Fulling an inside space of a device with big caps it lower the ventilation capabilities, it increase the PCB dimensions, and so on... Not about many advantages also...
Definitely, there is not rational or any functional reason to use f. ex. a 63v rated cap for a 12v working voltage. A 63v rated cap should be used in a rational manner for a 50v working voltage area/circuit.
When about mass production consumer devices, there may be economical/financial reasons for a such use. There are deals between the device manufacturer and caps providers which favorise use of such standard voltage rated for the whole design. There are discounts involved in businesses, as another similar production/financial reasons, which it have very little to do with the in fact devices functionality, but more about organising the production, costs, profit, and so on (in this direction)...
Edits: 06/25/16
It's not a good idea to run electrolytics at less than 50% of their voltage rating, otherwise, some margin is good.
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: