Changing R1's value is not supposed to affect Vr1,Vrr directly. Change of close distance radiated heat from M1 M2 due to CCS level reprogramming by R1 may affect Q2's Vbe a little to slightly differentiate the current through Vr1,Vrr (substituted by especially steady resistors in your build). That could change Vout a little.
Nice that there was UBiB effect and you like it so much in your application above. Thanks for the kind words. Wishing a happy new year to you and to everybody!
Thanks, SALAS, and a very prosperous and happy 2023 to you.
Since the heat did not alarm you I think I will leave it alone. It doesn't bother me - I worried that maybe I had gone too far!
I measure 1.1333 volts across R1 which does seem like lots of spare. What do you think?
Since the heat did not alarm you I think I will leave it alone. It doesn't bother me - I worried that maybe I had gone too far!
I measure 1.1333 volts across R1 which does seem like lots of spare. What do you think?
That's 1.5A CCS for 0.75Ω. 1.13V is > than 0.6V that we usually expect there. If Q1 is good, maybe its due to low Vce and heat. Program at your device's boot max current +25% tops I would say. To save some heat.
I can see what I did now.
I had blown up an earlier M1 and could not get the holes cleared so I attached the gate stopper to the gate directly - I ran a wire from the drain to the output and connected R1 directly to the source bypassing Q1 unintentionally. In case this is not clear - M1 iws not in the holes on the PCB. I need to add another wire from R2 to the source to regain the use of Q1.
Will fix that and I suspect all will be in order.
How many times can you thank someone before they tire of hearing it? I will take my chances.
THANKS a trillion since a million is such a mundane multiplier these days.
I guess we know that FQP3P20 is rugged from this abuse?
I had blown up an earlier M1 and could not get the holes cleared so I attached the gate stopper to the gate directly - I ran a wire from the drain to the output and connected R1 directly to the source bypassing Q1 unintentionally. In case this is not clear - M1 iws not in the holes on the PCB. I need to add another wire from R2 to the source to regain the use of Q1.
Will fix that and I suspect all will be in order.
How many times can you thank someone before they tire of hearing it? I will take my chances.
THANKS a trillion since a million is such a mundane multiplier these days.
I guess we know that FQP3P20 is rugged from this abuse?
Now the voltage across R1 is 0.598 and the output voltage has remained about the same.
Now I fear that it won't sound the same - of course, it could well sound better - more likely!
I think my R1 looks a little discolored - I will replace it just to be safe when I make an order for parts.
I do not have a ohmmeter that will measure that low a resistance so I could not tell if the value has changed.
Would that voltage indicate it has moved closer to 1 Ohm?
THANKS for the help.
Now I fear that it won't sound the same - of course, it could well sound better - more likely!
I think my R1 looks a little discolored - I will replace it just to be safe when I make an order for parts.
I do not have a ohmmeter that will measure that low a resistance so I could not tell if the value has changed.
Would that voltage indicate it has moved closer to 1 Ohm?
THANKS for the help.
If your meter has a REL button (sometimes depicted as Δ) its also for zeroing test leads resistance when pressed together. To then measure small value resistors without that influence.
The 0.598V is indicative of Q1's correct Vbe proving its back in business so you now got a properly reacting CCS. Shall remain around 0.6V regardless of R1's exact value.
HI everyone,
I am building my first ultrabib. This one is for a PASS B1 buffer preamp which runs about 20mA so I targeted 120mA for R1[19.5vdc] So I started on variac and brought up to power slowly. LEDs are not super bright but lit and I get 17*18 vdc from 12V tran [just for testing] and Bourn pot does not do anything I just have rectified DC that changes with AC power input. I can measure resistance change with a lot of turns when powered off for the pot but it seems to max at 16.5K and not much lower than 9-10K. Is this typical for this pot or is it defective? I have checked and re-checked component layout and all looks right.
Thanks for any ideas. I wanted to check here before I removed and tried a different pot. Also I want to use for Shigaclone CD 8V supply which idle draw is around 200mA and playing up to 800mA, should I be OK with 900-1000mA max for R1 even when not running motors, or will this make for too much current to dissipate.
best regards,
Steve
I am building my first ultrabib. This one is for a PASS B1 buffer preamp which runs about 20mA so I targeted 120mA for R1[19.5vdc] So I started on variac and brought up to power slowly. LEDs are not super bright but lit and I get 17*18 vdc from 12V tran [just for testing] and Bourn pot does not do anything I just have rectified DC that changes with AC power input. I can measure resistance change with a lot of turns when powered off for the pot but it seems to max at 16.5K and not much lower than 9-10K. Is this typical for this pot or is it defective? I have checked and re-checked component layout and all looks right.
Thanks for any ideas. I wanted to check here before I removed and tried a different pot. Also I want to use for Shigaclone CD 8V supply which idle draw is around 200mA and playing up to 800mA, should I be OK with 900-1000mA max for R1 even when not running motors, or will this make for too much current to dissipate.
best regards,
Steve
Target 9-12Vout for testing with a 12Vac transformer. Wind down the Vout trimmer a lot. At about 5k range and below. If it refuses maybe its shot so try another trimmer. Also see if Q2 has normal 0.6V Vbe.
For the Shiga its going to dissipate all rest constant current when idle, better use an L-Adapter for such.
For the Shiga its going to dissipate all rest constant current when idle, better use an L-Adapter for such.
I'm using two Salas SSL1.3 UltraBiB boards with miro’s v1.3 AD1862 DAC board. I’m using the 2 Salas shunt regulator boards to power the two AD1862 DACs and two LM6171 op amps (one for +12vdc and another for -12vdc). The BOM shows 8x100uF for the +-12vdc. I read from one of your post that the electrolytic capacitors for the +-12vdc rails on miro1360's DAC board should be kept very low in order for the shunt regulators to work properly. Big electrolytic caps will only deteriorate the sound of the shunt regulators. Should I use only use 8x10uF for the +-12dc instead of 8x100uF. Is there a thread on the forum that addresses this issue?.
Thanks,
dkalendra
You got to compare and decide to make sure I guess. Since we don't know the priority of local decoupling uF total in the specific application.
Dear SALAS,
You have mentioned that increasing the value of C2 has potential benefit of lower noise for digital circuits.
1mF is suggested - since my supply sees 13 volts maxumum at the input I am wondering if I can take this a step further using a 2.2mF 25 volts cap for C2?
Worth a try or something to avoid?
AS ALWAYS your opinion would be greatly appreciated.
Take care,
You have mentioned that increasing the value of C2 has potential benefit of lower noise for digital circuits.
1mF is suggested - since my supply sees 13 volts maxumum at the input I am wondering if I can take this a step further using a 2.2mF 25 volts cap for C2?
Worth a try or something to avoid?
AS ALWAYS your opinion would be greatly appreciated.
Take care,
Hi, you can try use it but it will take twice as long to reach target Vout than 1mF without much more noise filtering benefit at very low frequencies in the specific impedance environment. Hope that's still fast enough not to interfere with a successful boot sequence. It can also kick back more energy in case of misuse.
I would rather suggest that experimenting with C2 quality, even bypass with small film may prove more interesting a tune up than simply making it bigger than 1mF.
I would rather suggest that experimenting with C2 quality, even bypass with small film may prove more interesting a tune up than simply making it bigger than 1mF.
Also REL is useful in sorting and matching parts values.
Say you got a bunch of 1k resistors. Measure one and press REL on it. Each other 1k resistor you measure it doesn't show whole value but +/- value difference from the first.
Say you got a bunch of 1k resistors. Measure one and press REL on it. Each other 1k resistor you measure it doesn't show whole value but +/- value difference from the first.