GB for Simple Cap-Mx Regulated Low-Noise PSU

[jimk04]

I'm too using LT1963 for Rpi....no real heat to worry about ....yes indeed good psu!

 

[xrk971]

Drpro,
That PSU looks really nice. Wish I had once packaged as nicely!

Is the sound with this PSU in RPi working out?

 

[drpro]

Hadn't had a chance yet, X. Very soon.

 

[redjr]

X,

I'm trying to put to use your simple cap-Mx PSU along with a TPS7A74xx LDO board. I've set the output voltage to 5.0VDC on the LDO, and using an upstream SMPS PSU of 12VDC. As can be seen in the photos, I'm getting 6.14 volts instead of 5 volts Is there some other part I need to substitute on the cap-MX board to achieve a 5.0v output?

 

[xrk971]

I think you need to bridge the two pins on far left in order for circuit to work properly.

That is, add a jumper (or solder bridge) between pin 1 (removed) and pin 2.

 

[redjr]

Thanks. What is pin 1 (EN) used for?

 

[xrk971]

Pin 1 is EN and tied to Pin 2 (INPUT), Pin 3 is GND, Pin 4 is OUTPUT, pin 5 is GND.

Cut pin 1 and 5 to allow use as 78xx regulator. Pin 4 is internally tied to SENSE on the chip. Pin 1 needs to be tied to Pin 2 to enable operation.

Here is datasheet:
http://www.ti.com/lit/ds/symlink/tps7a4701-ep.pdf

 

[redjr]

Thanks for that. I did read later that EN was for enable. However, even after shorting pin 1 and 2, I was still getting the same 6.14VDC. I'm trying another LDO. My son is desoldering the original as I write this. I had only tacked it in place to test.

 

[redjr]

It looks like the particular LDO I'm using requires an additional 25.5k resistor. Trying to test one now.

 

[xrk971]

How are you setting the voltage? With pot of programming jumpers? The pot can be adjusted to get you any voltage you need by monitoring the output voltage and turning the screw. So not sure how you set it to 5v?

Edit: your image shows the programming pads. But you need to disable the pot as it was set up for the pot. You will have to remove the pot or one of the fixed resistor. I would just use the pot.

 

[redjr]

How are you setting the voltage? With pot of programming jumpers? The pot can be adjusted to get you any voltage you need by monitoring the output voltage and turning the screw. So not sure how you set it to 5v? I tried setting the 5v by shorting the correct pads. My son tried just using the trim pot and was able to dial-in ~5V. I think we've figured it out. Thanks for your assistance.

Edit: your image shows the programming pads. But you need to disable the pot as it was set up for the pot. You will have to remove the pot or one of the fixed resistor. I would just use the pot.

 

[jimk04]

Can I feed raw DC into this....straight from rectifiers.
I have 1000uF Pana FC on the input side of the SimpleCapmx

 

[xrk971]

Yes, as long as the internal cap has enough capacity to smooth it more than what the cap Mx needs (3v or less ripple).

 

[jimk04]

Thanks for the quick reply X
For clarity I have 2 x 1000uf on the CapMx board and feeding Ian Ian Canada Reciever so pretty low consumption at 5v as far as I know.

 

[xrk971]

You are going to be fine. This is a great supply for DACs and preamps.

 

[twocents]

Voltage regulator options

I have two of these excellent PSU’s running daily in my system – one (ultra low noise) for a DAC and another for the RPi. Now I want to build a third one for a new headamp. Problem is I need a 24V regulator for the headamp and was hoping to use the LM7824 - only to find that they are also obsolete now, like many other popular audio components. However, it looks like this is an even better option – the L78xxACV series from ST Microelectronics. Their output noise voltage is only 10uV and they have a higher output current of 1.5A. Should work very well here and I am certainly going to try this for my new Hakuin headamp.

 

[jimk04]

What about one of these in 24v flavor. Based on low noise Ti chip

#Aliexpress Your ￡0.83 in coupons are here!
Lusya SUQIYA Sigma78 Series LDO Low Noise Step Down Linear Regulated Power Supply Module T0703|Amplifier| - AliExpress

Would fit right into the Capmx

 

[twocents]

Thank you for sharing jimk04. That is certainly a great option for a DAC application.

 

[xrk971]

That’s a great price and nice options for voltages. Thanks!

 

[TboneAK]

Hi X,

Looking building NP's 6-24 Xover from the store. I'd like to skip using a wall wart. I need 24vdc, and have a Antek AS-0515 tranfo that I was going to use for a B1. Well I have a spectacular Yarra rolling now, and was hoping I can use it for this 6-24 xo project. If I connect the secondaries in series to sum 30vac, what do I need to do other than put a bridge rectifier between it and the Cap-Mx?