Reflektor-D builds

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cam217

Member
Joined 2011
This thread is very interesting! But I still have questions :p

I am currently working on a DAC based on DDDAC (Ti PCM1794A). This DAC will be powered by a 3.3V for digital, 8V for analogue section and 15/-15V for the buffers.
I was thinking of using a Reflektor-D for the 3,3V and SSLV BiB for 8,15 & -15V.

I get roughly 10mA consumption with the 3.3V, 100mA on the 8V and 70mA on each 15/-15V.
I also plan to have a 5v Reflektor-D for Ian FIFO and another one for Ian reclocking board.

I also have a other concern which is space in my regular enclosure (430mm x 300mm x 76mm). I thought I could go on SMD for resistors (except R1/R6), transistors (except M1/M2), then redesign the board to get something smaller.
I found MMBT4403 that could replace the 2N4403TA because they seems to share a lot of characteristics except for power dissipation. Would it be ok?

For the 3.3V, I was thinking of 2.5R to 3R for R1. Will this work well for the 10mA consumption?

Thank you for all your hard work & help Salas.
 
T

TioFrancotirador

Member
Joined 2014
Salas said:
Haven't directly compared them in that position. Caddock MP 900 series had enough positive subjective recommendations by DCB1 users for setting the main CCS nonetheless. If that info is of any value in a different purpose regulator with different client circuitry to feed of course.
Click to expand...

I just put Caddocks MP930 for R1 (Previously had Mills). I must say I was expecting more, but there is slight improvement in transparency and clarity. However still out of many mods seems that ones affecting regulation circuit directly are of most benefit:
1. Transistor instead of resistor.
2. Mundrof 4 pin for Vref Led filtering.

Wonder if actually bypassing Mundorf 4 pin with some 0,1uF film would bring further benefits. Something like:
Leds in between of Mundorfs Vout - and Vin + and then film cap between mundorfs Vin - and Vout +. So Mundorf is filtering Leds noise and film cap is filtering mundorfs HF noise.

Has anyone tried that?
 
Tea-Bag

Tea-Bag

Member
Joined 2006
Paid Member
cam217 said:
This thread is very interesting! But I still have questions :p

I am currently working on a DAC based on DDDAC (Ti PCM1794A). This DAC will be powered by a 3.3V for digital, 8V for analogue section and 15/-15V for the buffers.
I was thinking of using a Reflektor-D for the 3,3V and SSLV BiB for 8,15 & -15V.

I get roughly 10mA consumption with the 3.3V, 100mA on the 8V and 70mA on each 15/-15V.
I also plan to have a 5v Reflektor-D for Ian FIFO and another one for Ian reclocking board.

I also have a other concern which is space in my regular enclosure (430mm x 300mm x 76mm). I thought I could go on SMD for resistors (except R1/R6), transistors (except M1/M2), then redesign the board to get something smaller.
I found MMBT4403 that could replace the 2N4403TA because they seems to share a lot of characteristics except for power dissipation. Would it be ok?

For the 3.3V, I was thinking of 2.5R to 3R for R1. Will this work well for the 10mA consumption?

Thank you for all your hard work & help Salas.
Click to expand...

Have you considered the Reflektor-Mini? Much smaller board than std reflektor-D, you just have to drill transistor to chassis.
 
C

cam217

Member
Joined 2011
Tea-Bag said:
Have you considered the Reflektor-Mini? Much smaller board than std reflektor-D, you just have to drill transistor to chassis.
Click to expand...

I found out last week-end there is a Reflektor mini but without rectification. Also I believe it doesn't have the same performance. It forces me to install mini & flexy if I want rectification, right? It might need more investigation :p
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
It is the same circuit. Its more fixed to can be small is the difference. I.e. it has normal two wire output only but it can have nearer proximity in installation and has DC input only. It nonetheless sports the JFET mod and the Flexy can take the four pin Mundorf. You can use any other suitable rectification board though. Flexy has transformer anti-ringing snubber parts places ready also for those who know how to do that.
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
TioFrancotirador said:
I just put Caddocks MP930 for R1 (Previously had Mills). I must say I was expecting more, but there is slight improvement in transparency and clarity. However still out of many mods seems that ones affecting regulation circuit directly are of most benefit:
1. Transistor instead of resistor.
2. Mundrof 4 pin for Vref Led filtering.

Wonder if actually bypassing Mundorf 4 pin with some 0,1uF film would bring further benefits. Something like:
Leds in between of Mundorfs Vout - and Vin + and then film cap between mundorfs Vin - and Vout +. So Mundorf is filtering Leds noise and film cap is filtering mundorfs HF noise.

Has anyone tried that?
Click to expand...

The good reports were about moving from a generic high ppm resistor to the high spec ones, but when already having a Mills its a matter of preference I would think.

About bypasses and the four pole Mundorf I really don't know what to expect.
 
C

cam217

Member
Joined 2011
Salas said:
It is the same circuit. Its more fixed to can be small is the difference. I.e. it has normal two wire output only but it can have nearer proximity in installation and has DC input only. It nonetheless sports the JFET mod and the Flexy can take the four pin Mundorf. You can use any other suitable rectification board though. Flexy has transformer anti-ringing snubber parts places ready also for those who know how to do that.
Click to expand...

I thought it would be a nice alternative although if wires are a little bit longer like 15cm I think it's better if I can have the sense function. Mini doesn't really fit my size constraints, I would like it to be no more than 50x60mm because I want to put them vertically next to each other with 70mm height maximum all M1/M2 bolted to one big copper bar for dissipation. I believe the copper bar from one side to the other in the enclosure would help separate power from signal for electromagnetic interferences.

Can you confirm in 3.3V setting the R1 value of 3R for 10mA consumption (should I prefer 2.5R?) and the SMT alternative for 2N4403TA. My concern is mainly about power dissipation, 2N4403TA has 625mW and MMBT4403 has 350mW. I still can measure Idss if I need to be sure of consistency of characteristics.

Thank you for your help
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
R1=3R means 200mA CCS current. Its nice to have much spare but not strictly necessary for so low consumption as 10mA. 100mA CCS could also do. ICCS=0.6V/R1. Has not to do with the voltage output. BJTs mW won't be a concern at such low voltage levels too.
 
C

cam217

Member
Joined 2011
Salas said:
R1=3R means 200mA CCS current. Its nice to have much spare but not strictly necessary for so low consumption as 10mA. 100mA CCS could also do. ICCS=0.6V/R1. Has not to do with the voltage output. BJTs mW won't be a concern at such low voltage levels too.
Click to expand...

What I don't really get is the relation between the CCS and the current draw from the Reflektor. But thanks for the confirmation ;)

I will have to make an other one for powering the Raspberry Pi 2B and I'm not sure until which current consumption these SMT trannies will work in 5.6V setting.
 
pidesd

pidesd

Member
Joined 2008
cam217,

in case you would be interested...

i have tested quite a few regs and configuation (except reflektor) with my pcm1794 dac analogue supply, and i have settled for now with the salas bjt-referenced current source with irfp240 as mosfet.

and for shunt portion, i use the original topology with jfet mod supplying the reference bjt and irfp240 again as shunt element (it is a negative supply with own transformer).

....and don't forget to pump-up the bias current! :) (i found it was quite rewarding in my case)

(i plan on putting roughly 1 amp on my in the future)

also, i have quite a long CRCRC,etc...chain as prereg.

in any case, don't be afraid to experiment,

my 2 cents....
 
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