RPi power
For my TDA1387 RPi HAT DAC build I finished the second XRK Simple Cap-Mx Regulated Low-Noise PSU v1 beta board yesterday. On this board I used a MC7805CTG 5V (10uV output noise) regulator for powering a Raspberry Pi 2B. I wanted a PSU that can deliver a little more than 1A for the RPi, so I used a (huge) 1mH 2.5A inductor for L101. It works great. The MC7805CTG regulator is pretty accurate, giving a stable 5.04V. My RPi runs headless with only a USB WiFi dongle, and this PSU seems to drive my RPi perfectly for the purpose. The HAT DAC board is powered separately with another of XRK’s PSU v1 beta boards with a TPS7A4701 (4uV output noise) regulator.
With the DAC output to my PCA (Class A) headamp and powering the RPi with this second low noise PSU (through the RPi GPIO header pins) results in absolutely no noise. Absolutely dead quiet with the volume on max, where previously when using the standard Raspberry supplied psu there was some feint background noise on full volume.
This is a truly budget setup that sounds absolutely stunning to my ears. Thank you X for such an effective, simple and cheap solution!
For my TDA1387 RPi HAT DAC build I finished the second XRK Simple Cap-Mx Regulated Low-Noise PSU v1 beta board yesterday. On this board I used a MC7805CTG 5V (10uV output noise) regulator for powering a Raspberry Pi 2B. I wanted a PSU that can deliver a little more than 1A for the RPi, so I used a (huge) 1mH 2.5A inductor for L101. It works great. The MC7805CTG regulator is pretty accurate, giving a stable 5.04V. My RPi runs headless with only a USB WiFi dongle, and this PSU seems to drive my RPi perfectly for the purpose. The HAT DAC board is powered separately with another of XRK’s PSU v1 beta boards with a TPS7A4701 (4uV output noise) regulator.
With the DAC output to my PCA (Class A) headamp and powering the RPi with this second low noise PSU (through the RPi GPIO header pins) results in absolutely no noise. Absolutely dead quiet with the volume on max, where previously when using the standard Raspberry supplied psu there was some feint background noise on full volume.
This is a truly budget setup that sounds absolutely stunning to my ears. Thank you X for such an effective, simple and cheap solution!
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Hi Twocents,
Very nice build and good idea to try a MC7805CTG to get higher current and low noise. Great news to hear that this simple little PSU is doing what it was designed to do. Your idea of calling it the SCAMULON is great.
S(imple) CA(p) MU(ltiplier) LO(w) N(oise)
So SCAMULON it is.
I actually use a 1mH on mine too and it doesn’t hurt, as long as the choke doesn’t saturate at the DC level you are using.
Very nice build and good idea to try a MC7805CTG to get higher current and low noise. Great news to hear that this simple little PSU is doing what it was designed to do. Your idea of calling it the SCAMULON is great.
S(imple) CA(p) MU(ltiplier) LO(w) N(oise)
So SCAMULON it is.
I actually use a 1mH on mine too and it doesn’t hurt, as long as the choke doesn’t saturate at the DC level you are using.
I just noticed that the TPS7A401 LDO low noise VR are available again. These have nice multi turn Bourns pots for the adjustment. Just cut off the two pins on the ends and jumper the enable to Vin. The remaining 3 pins follow 78xx pin format. Only $10.
TPS7A4701 Low Noise RF LDO Regulator Power Supply Module 1.5V-34V 3.3V 5V 12V 1A 699923682709 | eBay
Using a 24v 500mA Class 2 linear wall wart, I tested it here and it works great. I was able to run a 6.8ohm 5w resistor at 5v continuously. Also ran a 33ohm resistor at 16.4v. They got real hot but heatsinks on PSU remain under 40C.
TPS7A4701 Low Noise RF LDO Regulator Power Supply Module 1.5V-34V 3.3V 5V 12V 1A 699923682709 | eBay
Using a 24v 500mA Class 2 linear wall wart, I tested it here and it works great. I was able to run a 6.8ohm 5w resistor at 5v continuously. Also ran a 33ohm resistor at 16.4v. They got real hot but heatsinks on PSU remain under 40C.
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Playing with regulators
Just an update on my beta boards and regulators used. For my Raspberry Pi HAT DAC I am currently running two of these XLCLN Regulator boards. One with a TPS7A4701 (4uV output noise) regulator for powering the DAC, and the other with a linear LT1085CT-5 regulator for powering the Raspberry Pi. Still absolutely dead quiet and I am very very happy with the setup now. Just be aware that the LT1085CT-5 pinout is different to the board layout.
I was running a MC7805CTG 5V (10uV output noise) regulator previously for the Raspberry Pi, but started picking up problems with the Pi not booting or communicating (WiFi or UTP) properly – so this regulator does not seem to give enough current for running a Pi. The LT1085 3A now works very well. Probably not the quietest regulator out there, but I cannot hear a difference in my setup.
Just an update on my beta boards and regulators used. For my Raspberry Pi HAT DAC I am currently running two of these XLCLN Regulator boards. One with a TPS7A4701 (4uV output noise) regulator for powering the DAC, and the other with a linear LT1085CT-5 regulator for powering the Raspberry Pi. Still absolutely dead quiet and I am very very happy with the setup now. Just be aware that the LT1085CT-5 pinout is different to the board layout.
I was running a MC7805CTG 5V (10uV output noise) regulator previously for the Raspberry Pi, but started picking up problems with the Pi not booting or communicating (WiFi or UTP) properly – so this regulator does not seem to give enough current for running a Pi. The LT1085 3A now works very well. Probably not the quietest regulator out there, but I cannot hear a difference in my setup.