The SLB (Smooth Like Butter) Active Rect/CRC/Cap Mx Class A Power Supply GB

[xrk971]

There were two separate listings and one was dual rail but I just recombined them to same listing with two options for single or dual rail.

https://xrkaudio.etsy.com/listing/699792666

 

[sznobel]

Can anyone have a look at what's wrong here?

 

[xrk971]

Can you describe what we are seeing here? If you have a schematic please screenshot it and post it. I don’t want to have to unzip an ASC file and open it up in LTSpice etc.

 

[sznobel]

Can you describe what we are seeing here? If you have a schematic please screenshot it and post it. I don’t want to have to unzip an ASC file and open it up in LTSpice etc.

 

[xrk971]

Try bypassing the LT4320 with conventional bridge to see if it works. I have never used the model for LT4320, just know that it works. The cap multiplier is a well designed and tested circuit. I think Jhofland did LTspice simulations on it even. The output should rise from zero to final value about 1.5 to 3v less than the DC rail at the input.

 

[sznobel]

Try bypassing the LT4320 with conventional bridge to see if it works. I have never used the model for LT4320, just know that it works. The cap multiplier is a well designed and tested circuit. I think Jhofland did LTspice simulations on it even. The output should rise from zero to final value about 1.5 to 3v less than the DC rail at the input.

for one rail everything is ok, the problem arises when both rails are connected to GND. With a conventional bridge, the same thing happens

 

[xrk971]

You might be shorting it out by doing that. Please simulate the power trafo to galvanically isolate the voltage sources from the SLB ground.

 

[Bodyslam]

Hi X,

The single rail version seems to be sold out. Do you have an ETA for those?

Thx

 

[WalterW]

Hi guys, need some help...
I have build my own 'SLB-PSU', it is a combination of Salas L-adapter, SLB and Rod Elliot.
It has a voltage ref with LED's and a JFET CCS in it so I can choose any fixed voltage. It 's intended use is for a +12V 850mA power supply for a DAC.
See PIC's and schematic.

The problem is that if I measure over R3, the ripple with my multimeter on AC voltage, it goes wildly up and down. Also on a scope this gives a very unstable image. See pic below.
I have build exactly the same PSU's but without the Ideal bridge, with a normal bridge with schottky diodes, and everything is stable and I can read off the ripple in milliVolts on both the multimeter and scope.

Strange enough, DC wise everything is OK. The expected voltages are OK. All stable. And the cap multiplier filters all ripple off. but it seems to be a tiny bit higher then with the diode bridge.

Is this normal behaviour for a LT4320 Ideal bridge?
What do you guys measure over there? Should it be 'Smooth like butter' or is it very wild oscillating like mine?

(the datasheet says to put a 1uF ceramic capacitor over pin 5 and 6, so I did, there is also a 1uF MKP over it)

Grz, Walter

 

[xrk971]

The cap multiplier should not be combined with another circuit within its own feedback loop as you have done here. It would be fine to have the Rod Elliot LED based FET voltage regulator after the cap multiplier with its own power pass transistor. A two stage affair. I am afraid what you have made is an 16.7MHz oscillator. Since you say there is no oscillation when the active bridge is replaced with a passive bridge, I suspect that there is an interaction between the bridge MOSFETs and the cap multiplier. Too many actives. If you model this on LTspice, the oscillation will probably show up. Not sure if this will work but try putting a 10uH inductor in parallel with R2 and increase R2 to 10hms.

 

[Dolamike]

Hey all, I'm currently ordering parts for a SLB Power Supply and it looks like BD14016S is no longer available. Is there a recommendation for a replacement. Any help greatly appreciated, thanks.

 

[darrr]

Someone confirm if you can use this:
https://www.mouser.pl/ProductDetail/onsemi/BD140G?qs=vNc2DXHODiKZYq/ZL7wu8Q==

 

[xrk971]

That BD140 looks good. TTA004 would probably work too but check pin-outs.

 

[Mark Johnson]

ST makes the BD140-16 and it's in stock at US Mouser

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[Dolamike]

Thank you @Mark Johnson. I did see those as well. I'm curious, as a beginner to this hobby... on the ST version it has

- Power dissipation 1.25W

and for the Onsemi it has

-Power dissipation 12.5W

Is that something we should consider when comparing the two? Learning opportunity for myself here, please educate me. Thanks. 🙏

 

[Mark Johnson]

Here are the manufacturer's datasheets. They are more accurate than the summer interns Mouser hired, whose only job was to copy specs from datasheets into Mouser databases.

_

 

[Dolamike]

Hahaha, thank you. That makes more sense.