Hey Salas,
Just to be sure the terminology is correct at my end, Vgs is the conduction requirement? Part of the mosfet's specs yes? Does this change much and need to be tested or is it just taken off a spec sheet and is close enough?
That in conjunction with the LEDVf will give the Vd over R101. Just trying to understand a little more!
Thanks again!
Drew.
Just to be sure the terminology is correct at my end, Vgs is the conduction requirement? Part of the mosfet's specs yes? Does this change much and need to be tested or is it just taken off a spec sheet and is close enough?
That in conjunction with the LEDVf will give the Vd over R101. Just trying to understand a little more!
Thanks again!
Drew.
Its a curve VS current. http://www.diyaudio.com/forums/powe...-voltage-shunt-regulator-419.html#post2676368
Just a quick update... my DAC chassis plate is drilled and tapped now, all three regs powered up fine as expected. Targets are to be 14.9V, -13.9V, 300mA total on each, and 5.3V ~500mA (I'll measure the actual current of the Buffalo 2/Tridents to be sure what the load actually is). Did notice I will need to change out R303 for something smaller to get a proper range of adjustment, only goes to 5.45V right now. Dummy load is a wimpy 680 ohms just to get voltages in the ballpark. I ordered my Rset resistors before these first build reports came in (calculated 2V drop), so I'm not able to finalize this thing just yet. A variety of wirewounds on order but could be awhile as some are on backorder. Anxious to try this out after the good reports on sound quality. I'm getting there slowly....
Have you left the Legato's 6x100uF & 2x100nF local decoupling capacitors on board, or you have them removed?
Today arrived the two BJT + minikits from Mike, I will start to make them today, they are to change the Tridents 3.3V for Buffalo II TP stuff.
You can use down to 2u2 Zobel cap on BJT when you will inevitably do your usual Merlinesque subjective experiments. But no less than 4u7 when with MOSFET output on other regs. No bigger than 10uF in both cases do any good, rather restrict bandwidth. If there are decoupling capacitors in parallel with the reg output on circuits served, they can be changing the reg's parameters. They can be buffered with a central 100R in series at the +V input point on the client circuits PCB and hear if its better. That will form a mini RC, cutting enough interaction with the SSLV termination. Don't simply delete any of those local capacitors on digital circuits or linear op amps rails, they are usually critical for the chips.
But no less than 4u7 when with MOSFET output on other regs. No bigger than 10uF in both cases do any good, rather restrict bandwidth. If there are decoupling capacitors in parallel with the reg output on circuits served, they can be changing the reg's parameters. They can be buffered with a central 100R in series at the +V input point on the client circuits PCB and hear if its better. That will form a mini RC, cutting enough interaction with the SSLV termination. Don't simply delete any of those local capacitors on digital circuits or linear op amps rails, they are usually critical for the chips.Legato Caps
Mine is the Legato II. I asked Russ about the 100 uF caps, and he recommending keeping some decoupling in those positions regardless of power supply. Therefore I am using .1 uF Multicap PPMFX in place of the 6 100 uF electrolytics. Note I did not populate the Bal/SE converter, as I only use balanced outputs.
The (4) 10 nF caps are for the analog stage filter and not power supply decoupling, I use Rel RTE polystyrene box caps there, and for the compensation caps as well. A lot of "experts" on these forums recommended polystyrene as the best caps for filter/comp circuits in the analog stage of DACs. With Mundorf Supremes as output coupling caps, the sound is fantastic.
Sorry for the off topic, Salas et al, but I figure there are many people using these regs for Buffalo/Legato builds.
Mine is the Legato II. I asked Russ about the 100 uF caps, and he recommending keeping some decoupling in those positions regardless of power supply. Therefore I am using .1 uF Multicap PPMFX in place of the 6 100 uF electrolytics. Note I did not populate the Bal/SE converter, as I only use balanced outputs.
The (4) 10 nF caps are for the analog stage filter and not power supply decoupling, I use Rel RTE polystyrene box caps there, and for the compensation caps as well. A lot of "experts" on these forums recommended polystyrene as the best caps for filter/comp circuits in the analog stage of DACs. With Mundorf Supremes as output coupling caps, the sound is fantastic.
Sorry for the off topic, Salas et al, but I figure there are many people using these regs for Buffalo/Legato builds.
Barrows, i read your post into the TP support forum.
The main reason i asked you was to get feedback on how the regs react when connected to loads with low ESR local decoupling caps.
I will try the polystyrene swap.
Salas, having in mind the very low output impendance of the regs, is there a possibility for instability?
The main reason i asked you was to get feedback on how the regs react when connected to loads with low ESR local decoupling caps.
I will try the polystyrene swap.
Salas, having in mind the very low output impendance of the regs, is there a possibility for instability?
Barrows did not get any as it shows, else he would have got strong bad subjective hints about it. In any case try out the 100R buffering suggestion and judge in combination. Its a very easy experiment. More effective if there are enough value lytic decouplers. Not on the reg side, on the receiving V+.
2 questions about BIB Guide and BOM
I have two questions from the BOM relating to the BIB Guide.
1) Appendix 1 - talks about the Zener based configuration. If I am not going to use the Zener configuration, then I don't need the BOM Part C101 220uf/50v, I only need the MKT C102 part?
2) Appendix 4 - For the Output I can use a Zobel and use BOM Parts C104 and R107 or just use a ECAP BOM Part C103 47uf/50v and short R107 with a jumper?
Any help is appreciated as I am trying to understand the BOM before starting.
Thanks
I have two questions from the BOM relating to the BIB Guide.
1) Appendix 1 - talks about the Zener based configuration. If I am not going to use the Zener configuration, then I don't need the BOM Part C101 220uf/50v, I only need the MKT C102 part?
2) Appendix 4 - For the Output I can use a Zobel and use BOM Parts C104 and R107 or just use a ECAP BOM Part C103 47uf/50v and short R107 with a jumper?
Any help is appreciated as I am trying to understand the BOM before starting.
Thanks
1. If you are not going to use a Zener which has stronger noise, the MKT C102 part can be effective enough for filtering a resistive Vref, yes. Not as much as the 220uF polar on a resistor still, but a very good compromise between using better dielectric properties and noise. I have done the C101 polar populated underneath board and a film C102 on top bypassing it also. Had some Teflon 22nF ones begging.
2. You can use either solution, not both caps. The Zobel is recommended for more bandwidth. The 47uF electrolytic position comes in to play when with oscillation problems on some loads and/or for economic/size considerations. If with the 47uF, R107 needs be a jumper, correct.
2. You can use either solution, not both caps. The Zobel is recommended for more bandwidth. The 47uF electrolytic position comes in to play when with oscillation problems on some loads and/or for economic/size considerations. If with the 47uF, R107 needs be a jumper, correct.
You can use down to 2u2 Zobel cap on BJT when you will inevitably do your usual Merlinesque subjective experiments.
Thanks for the tweak, I have problems to get targeted Vout +3.3V
-Tx 9VAC 1A
-Vref 1red LED + 1K trimmer, rest jumpers
-R306 27R
-Smoothing cap 4700uF 16V
-R301 12R (Vout +0.696) trimmer don't adjust the Vout is fixed +0.696V) I tried with R310 3R9 (Vout +1.57) but still trimmer don't adjust the Vout is fixed 1.57V
-Dummy load 6R8
Pic show +1.57Vout with all LEDs lit but when changed R310 to 12R the red LED don't lit
