This isn't a technical question - but what does it cost to populate these boards?
At the present time I would like to power 4x F4 channels. Due to a lack of availability of the 300VA 18v transformers I am looking at using two Antec 400VA 18v transformers.
As a side note, some companies have a way to store a complete BOM for a project - is there anything like this - a timesaver that helps people get most of what they need by entering a project code?
At the present time I would like to power 4x F4 channels. Due to a lack of availability of the 300VA 18v transformers I am looking at using two Antec 400VA 18v transformers.
As a side note, some companies have a way to store a complete BOM for a project - is there anything like this - a timesaver that helps people get most of what they need by entering a project code?
Would anybody have a part number for heatsinks that fit this board that will work with a TO-247AD package? i.e. the Vishay FEP30DP-E3/45 diodes listed in the BOM.
The only other option i can come up with from Mouser is this 529801B02500G Aavid Thermalloy | Mouser and use TO-220 diodes with it.
The only other option i can come up with from Mouser is this 529801B02500G Aavid Thermalloy | Mouser and use TO-220 diodes with it.
Can someone elaborate in simple terms what the CRC-filter does in this PSU? All I can find online on CRC-filters, is how to calculate them; not what they do. And what determines the optimal value of R1-R4, R5-R8? Should I just keep that value as low as possible?
I may appear uneducated, but that's ok. I am quite new to this level of electronics.
I may appear uneducated, but that's ok. I am quite new to this level of electronics.
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the "normal" capacitor input filter is actually a RC filter.
The R is the effective resistance of the transformer.
This resistance is usually ignored because it is very small.
I refer to it as an rC filter.
It is a single pole low pass filter that rolls off at a slope of 6dB/Octave (=20dB/Decade) until the parasitics begin to dominate and then it stops becoming a effective filter.
The roll-off frequency can be predicted using the standard filter formula.
F-3dB = 1 /2/Pi/R/C
for R=0r5 and C=20mF, F-3dB ~16Hz
The rC does attenuate much of the audio band interference that enters from the transformer. But we can do better.
An extra RC stage can be added.
This RC adds on to the rC to give a rCRC filter.
This eventually rolls off at 12dB/Octave, but a bit slower at the start.
It attenuates the upper audio frequencies much more than the simple rC.
If you look at the ripple voltage, out of the rC filter, on the supply rail using a scope you see a sawtooth type wave with a little blip where the rectifiers turn off.
The corners are fairly sharp/pointed. these points indicate that lots of HF is in the ripple voltage.
The rCRC shows a more rounded ripple and usually the blip at rectifier turn off is just about invisible. This "rounded" sawtooth tells you there is less HF in the ripple voltage. i.e. the HF has more attenuation.
The more stages you add, the better the attenuation of the HF interference.
You can replace the R with an L (an inductor). This L creates a 2pole filter. Most will recommend an inductor that does not saturate at the highest currents drawn through the inductor.
Every inductor and particularly air cored, have some resistance, the L is actually L+R.
You can insert this to create an rC(L+R)C to get even better attenuation of the HF interference This is a 3pole filter.
You can avoid much of the arithmetic by using psud2
The R is the effective resistance of the transformer.
This resistance is usually ignored because it is very small.
I refer to it as an rC filter.
It is a single pole low pass filter that rolls off at a slope of 6dB/Octave (=20dB/Decade) until the parasitics begin to dominate and then it stops becoming a effective filter.
The roll-off frequency can be predicted using the standard filter formula.
F-3dB = 1 /2/Pi/R/C
for R=0r5 and C=20mF, F-3dB ~16Hz
The rC does attenuate much of the audio band interference that enters from the transformer. But we can do better.
An extra RC stage can be added.
This RC adds on to the rC to give a rCRC filter.
This eventually rolls off at 12dB/Octave, but a bit slower at the start.
It attenuates the upper audio frequencies much more than the simple rC.
If you look at the ripple voltage, out of the rC filter, on the supply rail using a scope you see a sawtooth type wave with a little blip where the rectifiers turn off.
The corners are fairly sharp/pointed. these points indicate that lots of HF is in the ripple voltage.
The rCRC shows a more rounded ripple and usually the blip at rectifier turn off is just about invisible. This "rounded" sawtooth tells you there is less HF in the ripple voltage. i.e. the HF has more attenuation.
The more stages you add, the better the attenuation of the HF interference.
You can replace the R with an L (an inductor). This L creates a 2pole filter. Most will recommend an inductor that does not saturate at the highest currents drawn through the inductor.
Every inductor and particularly air cored, have some resistance, the L is actually L+R.
You can insert this to create an rC(L+R)C to get even better attenuation of the HF interference This is a 3pole filter.
You can avoid much of the arithmetic by using psud2
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The board has pads for 10mm snap-in caps.
Something like this would be ideal-- LLS1K103MELC Nichicon | Mouser
This is an 80v part
Remember that the max diameter of the cap is 35mm.
The crc filter makes a 6db/octave filter for the noise of the rectifiers, in addition to the filtering of the huge caps. 0.47ohm 3W resistors in the positions is what's normally done. That is the equivalent of a .12ohm 12W resistor and will make the PSU noise on the rails approximately 10db less than if no resistors were used.
What amplifier are you building?
Something like this would be ideal-- LLS1K103MELC Nichicon | Mouser
This is an 80v part
Remember that the max diameter of the cap is 35mm.
The crc filter makes a 6db/octave filter for the noise of the rectifiers, in addition to the filtering of the huge caps. 0.47ohm 3W resistors in the positions is what's normally done. That is the equivalent of a .12ohm 12W resistor and will make the PSU noise on the rails approximately 10db less than if no resistors were used.
What amplifier are you building?
Thanks, guys! Quick and very clear explanations!
6L6: I'm preparing to build the Honey Badger in a dual mono configuration. It seems that, if I want to be well prepared (which I want to be), I have a little reading up to do. Seems like the quasimodo rig might also be of use to construct a good snubber within the PSU.
Would you think that, given the presence of the CRC-filter and HF-decoupling in the amp itself, a snubber is a necessity to get the amp to it's maximum sonic potential?
6L6: I'm preparing to build the Honey Badger in a dual mono configuration. It seems that, if I want to be well prepared (which I want to be), I have a little reading up to do. Seems like the quasimodo rig might also be of use to construct a good snubber within the PSU.
Would you think that, given the presence of the CRC-filter and HF-decoupling in the amp itself, a snubber is a necessity to get the amp to it's maximum sonic potential?
I'm having trouble understanding the resistor for the LED's. The suggested values seem to be very high. If I'm building the PSU for +/-25V, is that the voltage that the LED sees? I have super bright blue 3.2V, 20mA LED's. My calcs show 1K ohm resistors, but that's way less than the suggested 4.7-10k ohms.