So I recently built the B1K preamp and its sound great. I would like to ditch the wall wart, however, and build a dedicated linear power supply to feed it. From my understanding this needs to be a regulated 24V design.
Using Digikey's Schemeit I came up with a rough design I have seen in a few different places.
For the transformer, T1, I was thinking of using something like the Antek AS-0520, which is rated as 50VA. The regulator would be something like the LM7824 shown above.
Looking for suggestions or improvements for the rest of the design, size and make of capacitors, etc. I probably should also add a bleeder resister and possibly a power led as well. Also there is only one switch, but its labeled as S2, I am still getting used to the Schemeit interface.
I will probably put this is a small chassis, maybe one of the Dissipante models, 2U if it fits, or 3U otherwise, so I will have some heatsink capacity to work with for the rectifier and regulators.
Bonus if I can also get a regulated 5V out if this PS as well to power my external DAC. It would probably take a bit more than tossing in a 5V regulator due to the large voltage differential. Open to ideas.
Using Digikey's Schemeit I came up with a rough design I have seen in a few different places.
For the transformer, T1, I was thinking of using something like the Antek AS-0520, which is rated as 50VA. The regulator would be something like the LM7824 shown above.
Looking for suggestions or improvements for the rest of the design, size and make of capacitors, etc. I probably should also add a bleeder resister and possibly a power led as well. Also there is only one switch, but its labeled as S2, I am still getting used to the Schemeit interface.
I will probably put this is a small chassis, maybe one of the Dissipante models, 2U if it fits, or 3U otherwise, so I will have some heatsink capacity to work with for the rectifier and regulators.
Bonus if I can also get a regulated 5V out if this PS as well to power my external DAC. It would probably take a bit more than tossing in a 5V regulator due to the large voltage differential. Open to ideas.
I was also thinking using the 20VAC secondary might be close, and was considering going with a 22V secondary, but I could easily move to a 24V one as well. I had seen this circuit in a few places and the 20 VAC was what was suggested, but they might not have had the heat sink capacity I am planning on using, so cut it closer to the lower limit.
I get I will lose a bit of voltage across the rectifier diodes and if I add a resistor as was suggested I would lose a bit more. Also under load the rail would drop, so I agree its probbaly a better idea to run the voltage a bit higher and let the regulator do its job. I plan to use a case with plenty of heat dissipation capability so the increased heat shouldn't be an issue.
I haven't really researched other regulators too much, I just had seen the LM7824 seems pretty popular and some comments that its also fairly low noise. So I appreciate the alternative suggestions.
I get I will lose a bit of voltage across the rectifier diodes and if I add a resistor as was suggested I would lose a bit more. Also under load the rail would drop, so I agree its probbaly a better idea to run the voltage a bit higher and let the regulator do its job. I plan to use a case with plenty of heat dissipation capability so the increased heat shouldn't be an issue.
I haven't really researched other regulators too much, I just had seen the LM7824 seems pretty popular and some comments that its also fairly low noise. So I appreciate the alternative suggestions.
As mentioned earlier, I would also like this unit to power my 5V devices, I have an external DAC and also use a Pi based network music streamer setup.
The Pi uses a max of 5.1V / 3.0A DC and the DAC uses 5V / 500ma DC, so rounding up call it 4 Amps. I also think the DAC will run fine at 5.1V, as I have powered it off the Pi before, so having a separate 5.1V / 4 or 5 amp DC circuit should suffice. Those devices will probably only draw a fraction of their max, maybe a combined 1-2 amps under normal load.
I could simply use another regulator to knock the 24V output from the main circuit down to 5V, or use two regulators to lower it in stages 24V > 12V > 5V. Rayma had commented this would probably not be worthwhile due to noise, so I thought about two other possibilities.
The Antek transformer has dual secondary windings, so I could use one for each supply and have separate circuits from the transformer forward; one for the 24V output and the other for the 5.1V outputs.
I don’t know if this would cause any issues with an imbalanced load on the transformer by inducing any unwanted noise, etc. After all the whole point of this build it to provide as clean as power as I can to my devices.
Or I could simply buy a smaller 9V-50VA transformer and just have two dedicated circuits in the same chassis for each voltage. They would then only share the incoming AC mains. I could also isolate the grounds from one or both circuits from the chassis if that would help prevent noise or ground loop issues.
The Pi uses a max of 5.1V / 3.0A DC and the DAC uses 5V / 500ma DC, so rounding up call it 4 Amps. I also think the DAC will run fine at 5.1V, as I have powered it off the Pi before, so having a separate 5.1V / 4 or 5 amp DC circuit should suffice. Those devices will probably only draw a fraction of their max, maybe a combined 1-2 amps under normal load.
I could simply use another regulator to knock the 24V output from the main circuit down to 5V, or use two regulators to lower it in stages 24V > 12V > 5V. Rayma had commented this would probably not be worthwhile due to noise, so I thought about two other possibilities.
The Antek transformer has dual secondary windings, so I could use one for each supply and have separate circuits from the transformer forward; one for the 24V output and the other for the 5.1V outputs.
I don’t know if this would cause any issues with an imbalanced load on the transformer by inducing any unwanted noise, etc. After all the whole point of this build it to provide as clean as power as I can to my devices.
Or I could simply buy a smaller 9V-50VA transformer and just have two dedicated circuits in the same chassis for each voltage. They would then only share the incoming AC mains. I could also isolate the grounds from one or both circuits from the chassis if that would help prevent noise or ground loop issues.
If your secondary voltage is 23VAC or greater (example: Antek AS-0525) then the double regulated (double smoothed) power supply from the Ship Of Theseus "Hornet" front end card, might be an excellent choice. PCB mounted heatsinks for the two NPNs would be needed. If you're an LTSPICE user, plop it in and simulate its performance. Cowabunga?
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