goldenreference low voltage power supply

[luvdunhill]

How sensitive is this supply to external capacitance? It seems low-Q capacitors such as film bypass could cause lower performance. Has anyone looked into this?

[mwl168]

 

5 hours ago, mdr30 said:

Leds close to big caps light up, then dies. Same thing when powering up once again. Other leds unaffected. Amp boards OK (Dynalo). Any ideas what it could be?

Did you measure the regulated voltage when the LEDs went dim after power up?

In my experience, those LEDs close to the pre-reg filter caps only lit up when regulated voltage is achieved. Is it possible somehow the regulator sagged because the load is drawing more current than the PS can supply?

Edited May 7, 2016 by mwl168

[mdr30]

On 2016-05-07 at 8:16 PM, mwl168 said:

 

Did you measure the regulated voltage when the LEDs went dim after power up?

In my experience, those LEDs close to the pre-reg filter caps only lit up when regulated voltage is achieved. Is it possible somehow the regulator sagged because the load is drawing more current than the PS can supply?

Thanks for info - seems the voltage was just at the limit of the regulator's range. Changed back to original 1,5K resistors (from 1,8K) so now DC out is 19,5V (before 21,5V) from a AC18V transformer. All leds are on. Problem here is the mains moving from 210 to 230V and those swings seem to affect the whole GRLV system.

[kevin gilmore]

and this is why I try to design for the lowest dropout voltage possible. Especially true on the high voltage supplies.

But still you have to have enough to work with at least 5% low line voltage. so you need a different transformer.

[mwl168]

For my GRLV configured for +/- 20VDC regulated output, the dropout voltage was slightly below 3 VDC. As Kevin said, you need a transformer with higher voltage secondaries to account for mains fluctuation.

[headinclouds]

I need a few more GR LV single boards, so will buy some.  If you would like to be included, please see my post in the Carbon build thread.

 

[sbelyo]

What is the correct zip file for the latest tested dual supply board?

[Laowei]

41 minutes ago, sbelyo said:

What is the correct zip file for the latest tested dual supply board?

http://gilmore.chem.northwestern.edu/boards/goldenreference6.zip

[mwl168]

I have a question about the voltage setting; if I want to configure the GRLV to output, say, 5.5VDC. Is it as simple as using a LT1021-5 5V voltage reference and change the R7 and R8 resistors to arrive at the 5.5VDC output?

My plan is to use the positive half of the GRLV to power the digital section of my DAC.  

[kevin gilmore]

never tried it that way.  a little over the top to use this to power digital.

does look like it will work.

 

Edited May 28, 2016 by kevin gilmore

[mwl168]

Thanks Kevin. 

43 minutes ago, kevin gilmore said:

... a little over the top to use this to power digital...

Do you have some concern about using the GRLV for digital? 

To be specific, I am thinking about the possibility of using the GRLV to power the ESS9018 based Buffalo II DAC and potentially the USB receiver/reclocker/isolator too. I am expanding my Buffalo II DAC to dual mono setup and add the Amanero/Hermes/Cronus USB-to-I2S receiver. Between the 3 they may draw as much as 1.2A current.

Speaking of that, really looking forward to your multi-bit DAC.   

[kevin gilmore]

its fine for digital, just seems a bit of overkill when a standard 3 terminal regulator is enough.

definitely change d4 to 5.1v

4.7v is too low and it will not start.

 

 

Edited May 28, 2016 by kevin gilmore

[luvdunhill]

Look at the TPS7A4700. There are some very creative layouts on eBay even. It's a 4uV noise design and pretty much plug and play.

[mwl168]

24 minutes ago, kevin gilmore said:

its fine for digital, just seems a bit of overkill when a standard 3 terminal regulator is enough...

Ah, I read your message all wrong - was thinking down the other direction. I am devoted to keeping the overkill spirit alive... 

Will report back my findings if and when I try it.

 

10 minutes ago, luvdunhill said:

Look at the TPS7A4700. There are some very creative layouts on eBay even. It's a 4uV noise design and pretty much plug and play.

I looked up the TPS7A4700, indeed many layouts available at eBay and quite a few talks over at DIYAUDIO about using it to replace the Trident regulator for Buffalo DAC. It's rated at 1A max current out so will need to do one-per-channel if I do decide to go this route. 

Thanks all again for your help!

[johnwmclean]

Mousers out of MJW21193 & MJW21194 for the moment.
Assuming MJW21195 & MJW21196 is ok substitute, I’ve cross reference data sheets and cannot see any problem. 

Edited June 18, 2016 by johnwmclean

[UFN]

The only difference between them should be that the -95/-96 pair are rated for a higher working voltage - nothing to worry about.

 

//UFN

[johnwmclean]

thanks UFN

[JoaMat]

Anyone have a spice model of GRLV to share?

[luvdunhill]

I can if you can provide some feedback on some changes send me your e-mail!

[cspirou]

I'd like to build the +/-20V version for a Dynalo mk2. What range of transformer voltages would work for this power supply? The silk screen says 25V-0V-25V however 24V is much more common for transformers. Is there a reason why 2x24V wouldn't work for this build?

[mwl168]

Two 24v secondaries will work just fine for the desired 20VDC regulated output. You can go down to 20v since the GR's drop out voltage is quite low. That information is in the thread somewhere. To power the balanced Dynalo you'll need plenty of current so I would recommend at least 1.2A for each secondary and make sure you have enough heatsinks for the pass transistors.  

Edited July 30, 2016 by mwl168

[cspirou]

9 hours ago, mwl168 said:

Two 24v secondaries will work just fine for the desired 20VDC regulated output. You can go down to 20v since the GR's drop out voltage is quite low. That information is in the thread somewhere. To power the balanced Dynalo you'll need plenty of current so I would recommend at least 1.2A for each secondary and make sure you have enough heatsinks for the pass transistors.  

Okay, it's nice to know I can go down to 20VAC. I am thinking of using a 50VA 2 x 22V antek transformer.

http://www.antekinc.com/as-0522-50va-22v-transformer/

It says the current is 1.1A at 22V but the datasheet they have says it can go to 3A under differing loads so I am not too concerned about current handling. If I am cutting it too close on the current I could go to the 100VA version but that seems to be overkill.

For the boards I see there is a goldenreference6 single board and a goldenreference7 dual board. Is there any particular advantage to using dual boards vs a single board?

[mwl168]

I think I used an Antek AS-0520 with the GR for my friend's SUSY Dynalo build. It's rated at 1.3A. I bolted the pass transistors to the chassis and it worked very well. Although I see it's out of stock at the moment.

The GR single board version offers more flexibility in chassis layout but requires one to use dual secondary transformers. I cannot think of other advantage/disadvantage personally but others may chime in. 

[cspirou]

For the V6 board with the 3 bridges, is it meant to work with all three bridges or are you suppose to use either one or two depending on the configuration you are using?

[kevin gilmore]

one bridge if you are running a 3 wire transformer, 2 bridges if you are running a 4 wire transformer