220mu/50V
just as an info,
just got my BG FK 220 microF/50V from Audionote England so they do exist
These will do perfectly in an Aleph 4.
Don´t really understand why it is so difficult to calculate the needed capacitor voltage. with 4k75 and 1k5 and 5 volts over the transistor (bias resistor not regarded as this makes things only better) the voltage can never go over 15 volts with a 48v supply.
With 1k5 1k5 as used in a few other Alephs the voltage would be
(48-4)/2 +4 = 26volts
william
just as an info,
just got my BG FK 220 microF/50V from Audionote England so they do exist
These will do perfectly in an Aleph 4.Don´t really understand why it is so difficult to calculate the needed capacitor voltage. with 4k75 and 1k5 and 5 volts over the transistor (bias resistor not regarded as this makes things only better) the voltage can never go over 15 volts with a 48v supply.
With 1k5 1k5 as used in a few other Alephs the voltage would be
(48-4)/2 +4 = 26volts
william
OK, now please remember my A4 rails are slightly under the 48V, actually measures 43V under load.
dV across C8 = 16V
Regarding cap ratings and what you can do to them, my other hobby is Tesla coils. We make high voltage (25kVAC) pulse caps from multiple strings of lower value PP caps. Now, the number you put in your series string has a dramatic effect on the total cap number for a given uF, and hence cost. So, we have "tested the limits" as it were of commercial PP caps and I can say with great confidence that there is a good safety margin in most commercial offerings.
Take a Wima FKP-1, rated at 2000VDC / 600VAC.
We are talking pulse discharge at 50-100 shots/s and voltage reversal/ringing at 100-200kHz ..... this is just slightly harder work than a HiFi amp
Now we run these as above using their DC rating ..... mine have been going several years with this sort of torture, no problem!
Others on the Tesla list have taken a single string and just kept turing up the kV until they blow ..... on average they take AC about 1.5-2x their DC rating !!!!!
Now before the educated take me apart, I do accept and realize that electrolytic caps are nowhere near as robust as PP caps, I'm not suggesting this for a second! Only, that I believe if you have a good quality electrolytic, then it will run happily at its rated voltage.
Regards
Mark
dV across C8 = 16V
Regarding cap ratings and what you can do to them, my other hobby is Tesla coils. We make high voltage (25kVAC) pulse caps from multiple strings of lower value PP caps. Now, the number you put in your series string has a dramatic effect on the total cap number for a given uF, and hence cost. So, we have "tested the limits" as it were of commercial PP caps and I can say with great confidence that there is a good safety margin in most commercial offerings.
Take a Wima FKP-1, rated at 2000VDC / 600VAC.
We are talking pulse discharge at 50-100 shots/s and voltage reversal/ringing at 100-200kHz ..... this is just slightly harder work than a HiFi amp
Now we run these as above using their DC rating ..... mine have been going several years with this sort of torture, no problem!
Others on the Tesla list have taken a single string and just kept turing up the kV until they blow ..... on average they take AC about 1.5-2x their DC rating !!!!!
Now before the educated take me apart, I do accept and realize that electrolytic caps are nowhere near as robust as PP caps, I'm not suggesting this for a second! Only, that I believe if you have a good quality electrolytic, then it will run happily at its rated voltage.
Regards
Mark
I agree with Mark.
There's been a lot of talk about how hard you can push a cap in other threads, but I'll reiterate what I said elsewhere: I'll run my caps at 80-90% of rated voltage without even blinking. 100% doesn't strike me as being unreasonable in some applications. This stuff of needing a 50V cap to run a 10V rail is silly--not to mention needlessly expensive. If you think your incoming AC is going to run wild on you, then regulate your rail.
Grey
There's been a lot of talk about how hard you can push a cap in other threads, but I'll reiterate what I said elsewhere: I'll run my caps at 80-90% of rated voltage without even blinking. 100% doesn't strike me as being unreasonable in some applications. This stuff of needing a 50V cap to run a 10V rail is silly--not to mention needlessly expensive. If you think your incoming AC is going to run wild on you, then regulate your rail.
Grey
Theoretically you could set it for 1/2 rail plus 4 volts, and it
would work for 30 years, but why get excited? Also, you
can always adjust the resistor values between v+ and the
collector of the NPN transistor to lower the voltage across
the cap, and this will also work fine. Being a nice dumb
circuit, there is nothing critical about these values at all.
would work for 30 years, but why get excited? Also, you
can always adjust the resistor values between v+ and the
collector of the NPN transistor to lower the voltage across
the cap, and this will also work fine. Being a nice dumb
circuit, there is nothing critical about these values at all.
Actually, when I was ordering parts for my Aleph 2s, Digikey was silly enough to be out of the voltage I wanted. Completely out. I looked at the next higher voltage and they had something like 3 pieces. Same for the next higher voltage. (This was getting near the end of the year as I recall, so they were probably drawing down stock for inventory reasons.) At any rate, I ended up getting something goofy like 75V or 100V caps before I could get enough quantity to have them the same on both channels. And that was with getting smaller voltage parts for the two caps on the negative inputs.
Of course, I suppose I could have waited another month or two for them to get in new stock...
Grey
Of course, I suppose I could have waited another month or two for them to get in new stock...
Grey
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