I've just fitted one from the latest GB into my TDA1387 NOS DAC, supplying 5 volts to the DAC module from a 12 V switcher. The improvement over the previous regulator, a 7805, is not subtle. The 6922 output buffers get their B+ from a SSHV1. Wiring's a bit messy, but noise is not an issue.
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hello, I ask if it is possible to raise the resistance value after the bridge, I have a 12vac transformer and I go out with 5vdc- 600mA, M1 very hot
Do you actually need the 600mA CC setting or you have allowed too high spare current? 100-150mA CC over the expected peak load demand suffices in this regulator. If CC can be fixed smaller for your application but still enough, M1 will cool down significantly. Regarding your question, yes you can use the Rf named resistor in a higher value as an RC voltage drop aid in this case. Simulate with Duncan's free raw PSU software to predict voltage drop and power dissipated on that resistor. Put together a virtual diodes bridge to an RC of Rf & 6800uF and a 0.6A constant current load to analyze. Change Rf value until enough DC drop for your purpose is eaten there.
https://www.duncanamps.com/psud2/
https://www.duncanamps.com/psud2/
I finally made up a J113 test rig. 20 no. samples all measure between 17 and 20mA.
Can I use 680r R4, 7 and 8?
Can I use 680r R4, 7 and 8?
Yes, 680R seems like a good compromise since your IDSS readings are at the transition mA range between my 560R & 750R recommendations.
Thanks Nick yes that was my reasoning having read the post on J113. Do we struggle for stable 5v with such mA IDSS?
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Its not so much about stable Vout as much as J3 to achieve high impedance as local ccs. Thus maintaining performance to spec. The higher its idss the higher its Vgs (off) and as you go lower Vout the margin across J3 decreases. M2 has a Vgs subtracted from Vout, what remains is for J3's Vds. It has to be >Vgs (off) for working in the saturation region (pentode style little angled flat) of the Jfet curves. Else it will still work, but in the ascending Ohmic (kinda triode looking) region before the flat and the impedance will be lower and susceptible. Few dB of open loop gain performance will be lost.
Hello everyone, looking for some advice here, I've finished my first Ultra BIB positive regulator, I have been having some trouble getting the voltage dialed in to 24v for my B1K, and could use some advice. I've attached a picture of my build, using ceramic insulators, Noctua NT-H1 thermal paste, and the bottom plate of my chassis as my heatsink. The chassis I am using is the same chassis as the B1K, a Modushop GX243, the baseplate is 230mm x 233mm x 2mm minus a few 4mm holes I have for mounting. Due to chassis height restrictions, the supplied kit 6800uF/50V Nichicon KG was too tall, as I had a 10000uF/50V Nichicon KG I subbed that in, but can easily swap to the 6800uF if needed. Transformer is a 25va 25vac Antek AN-0225 secondaries wired in parallel.
The problem I am facing I think has something to do with thermal drift. My house and the location of the PSU is regularly 72-73f, the chassis never seems to get very warm, and whether under load or just running the PSU alone, voltage does not hold stable. For example when going to sleep last night the PSU had powered on for 8 or more hours, and been at 24.01v for 1-2 hours, connected to the B1K powered on, when I woke up this morning and checked voltage had dropped to 23.75v. What seems to confuse me is that if the environment is stable and climate controlled with little to no fluctuations, and the chassis, with top plate in place is "warmed up" for the Ultra BIB, how does it drift over 8 hours?
I'm looking for some help getting this to maintain 24v without as much drift. The guide mentions measuring the VR1 point and placing a resistor in it's place, which I would like to achieve one day, but with this drift I am facing I am not sure. I also understand that I could use a zener diode in place of VR1, but I'd like to keep the PSU noise to a minimal, so a trimpot or fixed resistor would be more ideal to me.
The problem I am facing I think has something to do with thermal drift. My house and the location of the PSU is regularly 72-73f, the chassis never seems to get very warm, and whether under load or just running the PSU alone, voltage does not hold stable. For example when going to sleep last night the PSU had powered on for 8 or more hours, and been at 24.01v for 1-2 hours, connected to the B1K powered on, when I woke up this morning and checked voltage had dropped to 23.75v. What seems to confuse me is that if the environment is stable and climate controlled with little to no fluctuations, and the chassis, with top plate in place is "warmed up" for the Ultra BIB, how does it drift over 8 hours?
I'm looking for some help getting this to maintain 24v without as much drift. The guide mentions measuring the VR1 point and placing a resistor in it's place, which I would like to achieve one day, but with this drift I am facing I am not sure. I also understand that I could use a zener diode in place of VR1, but I'd like to keep the PSU noise to a minimal, so a trimpot or fixed resistor would be more ideal to me.
The -0.25V drift at 24V Out you describe is in a normal bracket for this design when with the trimmer. Its thermal due to the negative TC Vbe of Q2. As Q2 works gets bit warmer inside even if ambient is relatively stable. If your application really demands minimal drift you got to use a Zener in Vrr's place and remove the trimmer. But B1K is not a circuit relying on B+ nominal precision. In any case if choosing a Zener Vref in the reg you should up C2 at 1000uF killing most of Zener's noise and there are also RC filter cells in B1K's rail that will further filter noise.
By the way do fit the shorter 10mF/50V Nichicon normally on the board to avoid wires inductance, its a good C1 capacitor for the situation.
*For 24V Out a 19V 0.5W Zener with its cathode pointing at Q3 should be used but you can't be sure about 24V on the nose since Zeners have tolerances. It will be about there but stable for long time thermal drift.
Thank you for the information Salas, I think I will stick with the VR1 rather than muck with tolerances on zener diodes.
In regards to your C1 capacitor comment. Both the 6800uF and 10000uF Nichicon KG's are too tall for the chassis, hence side mounted. I do have a ELH688M050AS2AA and a 380LQ682M050J022 both 6800uF/50v that can mount on the board with no height problems, would one of those be a better choice? I couldn't find any "audio grade" caps in stock that met specs of 6800-10000uF/50v.
In regards to your C1 capacitor comment. Both the 6800uF and 10000uF Nichicon KG's are too tall for the chassis, hence side mounted. I do have a ELH688M050AS2AA and a 380LQ682M050J022 both 6800uF/50v that can mount on the board with no height problems, would one of those be a better choice? I couldn't find any "audio grade" caps in stock that met specs of 6800-10000uF/50v.
The CDE I would prefer. Straight mounting is a better choice anyway because it avoids the extension wires.
Did you feel a difference for B1K as it is? There was at least one other guy using Ubib for it I remember here. He was very positive about his. Because of B1K's B+ rail RC filters and Zeners I would have supposed that the initial power source's effect should had been damped enough.
Initial thoughts with the Ubib are that it sounds even better than my previous B1K supply and I'm very happy with it. I picked up enough to have kits for another positive board as well as a negative one. I think the B1K sounds fantastic even with just the inexpensive Triad wallwart, I've been running it for a bit with a Chinese regulator I found and the diyaudiostore SMPS filter, it's not the most noise free PSU, but the SMPS filter seems to smooth it a bit.
All of that said, you have to wonder at a certain point if what I am hearing as better is just my subconscious mind telling me "you spent money or made a change therefore it sounds better." Either way, I've gone far enough down the rabbit hole that I will be sticking with a nicer PSU for the B1K.
All of that said, you have to wonder at a certain point if what I am hearing as better is just my subconscious mind telling me "you spent money or made a change therefore it sounds better." Either way, I've gone far enough down the rabbit hole that I will be sticking with a nicer PSU for the B1K.
Keeping VR1 is you have a variable output independently cased shunt PSU useful for other circuits tests as well.