Power supply capacitors

[wchick]

Hi all,

Will 62000 uF, 40VDC capacitors good enough for Aleph 5 power supply? I'm concerned that 40VDC is not high enough because I saw others used 63 to 100V or higher. Also some capacitors have unit in MFD, what is it? Any thing similar to uF? Thanks for you advice.

Wallace

 

[roddyama]

Hi Wallace,

As long as you're running the standard 34VDC rail voltage, you will be fine, assuming you have good capacitors. You might want to search the forum for more information on using older electrolytics, or used electrolytics. There has been a lot of interesting discussion on the subject.

Rodd Yamas***a

 

[oliverniekamp]

The cappacitors will be enough but in my experience it will sound better to use more and smaller caps like 4*33000uF for example.
Big cappacitors tend to sound slow and heavy.

 

[wchick]

What is MFD and uF, same or different thing?

Thanks for the responses, one thing still confusing me is the MFD and uF of caps. Are they the same thing or not? Thanks.

Wallace

 

[trwh]

"Big cappacitors tend to sound slow and heavy."

Hmmm. It is certainly often cheaper and more convenient to use many smaller capacitors in parallel instead of one larger one.

wchick, yes MFD and uF are the same thing. I too found this confusing - I have seen some schematics where 1000uF was written 1M0, which could have meant 1mF = 1000uF (it was), 1uF, or 1MF (not likely!)

Thanks,
TRWH.

 

[woody]

You have it MFD and UF stand for the same thing. That is .000001F = 1MFD = 1UF and there is another way to
write this but I haven't learned it yet.


Regards, bob12345678

 

[hugobross]

about "the big caps tend to be slow"-thing
place a few different small caps in parallel over the huge one, this works fine

HB.

 

[jan.didden]

power supply caps

You have it MFD and UF stand for the same thing. That is .000001F = 1MFD = 1UF and there is another way to
write this but I haven't learned it yet.


Regards, bob12345678

No, not at all! 1mF=1000uF.
1MF=10^6F.
Let's keep this straight: m=milli, M=mega,u=micro
Not just in caps, also for instance in freq (1MHz=10^6Hz, 1mHz=.001Hz). So 1mF=.001F=1000uF. Sometimes on older diagrams you see 1uuF, which is just 10^-6X10^-6 or 1pF.
1mH=1000uF=10^-6H. 1MH should be quite a coil...
1MOhms=10^6Ohms, while 1mOhms=.001Ohms.
1MV=10^6volts, 1mV=.001V, 1uV=.001mV=10^-6V
1mm=.001meter.
You get the point.



Cheers, Jan Didden

 

[oliverniekamp]

Of cource you are right Hugobross, 1K across the 60K helps a lot, but in my case 4 times 33 was even better. Maybe its just that the Philipps are better than the spragues?

 

[oliverniekamp]

Janneman, thanks for that! I should print it out and put it on the wall because i allways get nervoes about the different ways to express the values.

 

[jan.didden]

Re: power supply caps

No, not at all! 1mF=1000uF.
1MF=10^6F.
Let's keep this straight: m=milli, M=mega,u=micro
Not just in caps, also for instance in freq (1MHz=10^6Hz, 1mHz=.001Hz). So 1mF=.001F=1000uF. Sometimes on older diagrams you see 1uuF, which is just 10^-6X10^-6 or 1pF.
1mH=1000uF=10^-6H. 1MH should be quite a coil...
1MOhms=10^6Ohms, while 1mOhms=.001Ohms.
1MV=10^6volts, 1mV=.001V, 1uV=.001mV=10^-6V
1mm=.001meter.
You get the point.



Cheers, Jan Didden

Oops, 1mH=1000uF=10^-6H must be of course be: 1mH=1000uH=10^-3H....

Jan Didden

 

[AGGEMAM]

Of cource you are right Hugobross, 1K across the 60K helps a lot, but in my case 4 times 33 was even better. Maybe its just that the Philipps are better than the spragues?

In my experience, parallel coupling devices of different values is always worse than parallel coupling multible devices of the same value.

Of course, it is even better if you can find a single device doing the entire thing well.

 

[trwh]

janneman, what you say about the SI metric prefixes is correct. However, in some cases manufacturers _do_ use MFD to stand for uF, as I outlined in my previous post.

So:

0.000001F = 0.001mF = 1uF sometimes written as 1MFD. Note that in fact the unit mF (= 1,000uF) is seldom used, i.e. people tend to write 10,000uF instead of 10mF.

Some of the metric prefixes are:

T (Tera) = 10^12
G (Giga) = 10^9
M (Mega) = 10^6
k (Kilo) = 10^3
m (milli) = 10^-3
u (micro) = 10^-6
n (nano) = 10^-9
p (pico) = 10^-12

Hope this helps,
TRWH.