Ungodly amounts of capacitance also has the disadvantage of a very low amount of time that they are charging in normal operation, which can lead to the transformer humming and heating as for such a long time it’s current has nowhere to go...
So i would be better of with a config of C-R-C 22mF each, so 4x22mF on each side?
And to check if it makes some difference with ~2000uF at the beginning and end.
And to check if it makes some difference with ~2000uF at the beginning and end.
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I think i will make a C-R-C-R-C config.
22mF - 1k - 22mF - 1k -22mF for 1 rail (positive rail), so one complete side (left for example) needs the same config for the negative rail.
Total amount will be 66mF for 1 side, think that;s better then my previous 'overkill'.
I think i will use 1k ohm / 7.5W resistors because the diagram says 4x0.47ohm = ~2kohm total.
Do i also need a 10-100nF at the end like in the Burning Amp PSU ?
22mF - 1k - 22mF - 1k -22mF for 1 rail (positive rail), so one complete side (left for example) needs the same config for the negative rail.
Total amount will be 66mF for 1 side, think that;s better then my previous 'overkill'.
I think i will use 1k ohm / 7.5W resistors because the diagram says 4x0.47ohm = ~2kohm total.
Do i also need a 10-100nF at the end like in the Burning Amp PSU ?
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Your resistor math is backwards. 4 resistors in parallel add up as 1 / (1/x + 1/x + 1/x + 1/x), so 4 x 0.47ohm equals 1 x 0.12ohm.
(Note also that "K" denotes 1000, so 1000 ohms would be waaay too big.)
Cheers,
Jeff.
PS: 4 resistors in series do add up the simple way. Capacitors are backwards: in parallel they add up but in series it's the 1/x rule again.
(Note also that "K" denotes 1000, so 1000 ohms would be waaay too big.)
Cheers,
Jeff.
PS: 4 resistors in series do add up the simple way. Capacitors are backwards: in parallel they add up but in series it's the 1/x rule again.
2x 60mOhm in a C-R-C-R-C (1x for posive side and 1x for negative side)...
Is 25W enough for a 1x 60mOhm R (3W each as indicated in the schematic)?
Is 25W enough for a 1x 60mOhm R (3W each as indicated in the schematic)?
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P=I^2 x R
with , say , 3A for Iq (per rail , in PSU common for both channels) , that is P= 3^2 x 0,06=0.54W of dissipation
3W is very good margin
with , say , 3A for Iq (per rail , in PSU common for both channels) , that is P= 3^2 x 0,06=0.54W of dissipation
3W is very good margin
Thanks.
Config will be for 1 complete side in C-R-C-R-C config:
- 6x 22mF / 63V / 105C capacitors
- 4x 0.06 ohm / 5W resistors
- 2x 100nF capacitor
Config will be for 1 complete side in C-R-C-R-C config:
- 6x 22mF / 63V / 105C capacitors
- 4x 0.06 ohm / 5W resistors
- 2x 100nF capacitor
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^This R-C combination will give a time constant of 0.06 Ohm x 22E-3 F = 1.3 ms, corresponding to a cut-off frequency of about 770 Hz (for each R-C combo). Given the 50 Hz mains (100 Hz after rectifiers), this seems a bit high. Could you use a larger resistor to improve the filtering of the mains hum? 1 Ohm or so would seem a bit better to me.
My knowledge of filtering is not so good, so any info is welcome !
I didn't ordering any, except some parts i have like the 300VA/20V (instead of the 18V) transformers for each side.
According to a online RC filter tool: 1 RC filter with 0.06R/0.022F the cutoff freq.=120Hz
I don't know what happend if i use another RC filter after this ... (is it still 120Hz)
And what's a good cutoff frequency (in my country we use 230V/50Hz) ?
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If you've got extra voltage then increase the resistor rather than decreasing the capacitance. That'll drop your voltage down a bit too....
Oups, I forgot a factor 2pi in my numbers Your online tools are correct. Getting down to 10 Hz or lower would be great.
Well, with the 22mF the R's should be 0.5ohm, that's too much i think.
Do you have any suggestion about a good CRC or CRCRC filter, or any links?
0.5ohm sounds perfect to drop a bit of excess voltage.
(Note that dropping voltage also means generating heat -- so this will need to be a chunky resistor.)
(Note that dropping voltage also means generating heat -- so this will need to be a chunky resistor.)
You lose a volt or so with a 2A load. As Jeff mentioned, if you have a bit of
excess voltage to burn, that should be fine.
So it all boils down to what compromises you want to make. If you want to
stick to the same corner frequency then you can increase the cap and
drop the resistance.
You might want to try out various combinations by simulating using this:
PSUD2
Cheers,
Dennis
excess voltage to burn, that should be fine.
So it all boils down to what compromises you want to make. If you want to
stick to the same corner frequency then you can increase the cap and
drop the resistance.
You might want to try out various combinations by simulating using this:
PSUD2
Cheers,
Dennis
Kingpin,
You seem to be struggling with some very basic concepts of power supply design. Have you built a power amplifier before? As you are starting to see, there are a few aspects of a design that need to be balanced or traded off with each other. A few of the kind folks here on the forum have been generous with their time and advice, but I am worried that you will need a lot more help. It is possible that you may burn some of your components before you are finished by making a simple mistake.
Perhaps it would be safer for you to use a simple PSU that has already been built successfully. If your case has room, then using one of the diyAudio Universal PSU boards for each channel would be a good way to go. This will make a simple CRC power supply that will work very well. I would suggest using 18mF capacitors in each location on the board, giving a total of 72mF for each rail, on each channel. The simplest thing to do for the resistors is to use four 0.47 Ohm, 3 Watt resistors in parallel, as is commonly done with these boards. The combined resistance would be 0.117 Ohms, and the cutoff frequency would be 37.6 Hz. Voltage drop in the CRC network would be 0.234 Volts (with 2 amp quiescent current), and power dissipated by each resistor will be less than 1 Watt. So a very safe design to use. Since the bridge rectifiers will drop anywhere from 2 to 3.5 Volts, rail voltages will also be safe for your Aleph J boards, using transformers with 20V secondaries.
If two of the diyAudio PSU boards will not fit in your case, then there will be a lot more to discuss.
You seem to be struggling with some very basic concepts of power supply design. Have you built a power amplifier before? As you are starting to see, there are a few aspects of a design that need to be balanced or traded off with each other. A few of the kind folks here on the forum have been generous with their time and advice, but I am worried that you will need a lot more help. It is possible that you may burn some of your components before you are finished by making a simple mistake.
Perhaps it would be safer for you to use a simple PSU that has already been built successfully. If your case has room, then using one of the diyAudio Universal PSU boards for each channel would be a good way to go. This will make a simple CRC power supply that will work very well. I would suggest using 18mF capacitors in each location on the board, giving a total of 72mF for each rail, on each channel. The simplest thing to do for the resistors is to use four 0.47 Ohm, 3 Watt resistors in parallel, as is commonly done with these boards. The combined resistance would be 0.117 Ohms, and the cutoff frequency would be 37.6 Hz. Voltage drop in the CRC network would be 0.234 Volts (with 2 amp quiescent current), and power dissipated by each resistor will be less than 1 Watt. So a very safe design to use. Since the bridge rectifiers will drop anywhere from 2 to 3.5 Volts, rail voltages will also be safe for your Aleph J boards, using transformers with 20V secondaries.
If two of the diyAudio PSU boards will not fit in your case, then there will be a lot more to discuss.
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Thanks for the feedback.
@TungstenAudio: well i do have some experience of building power supplies but only for low power applications like this for example "YouTube" based on a LDO principle but i never build an power amp.
So for me it's a learning curve and i really appreciate the feedback.
@TungstenAudio: well i do have some experience of building power supplies but only for low power applications like this for example "YouTube" based on a LDO principle but i never build an power amp.
So for me it's a learning curve and i really appreciate the feedback.
Thanks Dennis, will install it tomorrow and play with it.
And as TungstenAudio said i can always build the UPS.