Salas hi,
I assume the trim pot will dial up the proper Vout and then gets replaced with a fixed resistor. Then no need for C2, 1000uf bypass on the Zener.
Zeners causing too much noise?
FYI, I'm not a fan of those white albino monkey coffin resistors; I always use mills for higher wattage. IMHO of course.
Might you know of anyone with this designs PCB for sale? I "think" I saw James with it?
Thanks again.
Wheezer
Avoid thinking PCB, too much hassle for such a simple circuit. Ready options are Tea-Bag's GB Hypnotize boards that are compatible V1 for the regs part. Else you etch James's yourself.
The bypass cap REMAINS. Whatever the level of the Vref noise, low or high, has to be filtered because it gets directly amplified by the loop gain, and the AC impedance should stay low down to subsonic for the phase to stay flat in the pass band and the gain high. Don't go lower than 470uF. You may be tempted for a plastic one of few uF for bypassing the electrolytic, to experiment subjectively though.
The only quality parts can be the Vref bypass caps, and secondly the output one. No Mills will do anything, its just a DC set element. For the Vref use a low ppm when you fix it, that could be reasonable.
The bypass cap REMAINS. Whatever the level of the Vref noise, low or high, has to be filtered because it gets directly amplified by the loop gain, and the AC impedance should stay low down to subsonic for the phase to stay flat in the pass band and the gain high. Don't go lower than 470uF. You may be tempted for a plastic one of few uF for bypassing the electrolytic, to experiment subjectively though.
The only quality parts can be the Vref bypass caps, and secondly the output one. No Mills will do anything, its just a DC set element. For the Vref use a low ppm when you fix it, that could be reasonable.
IMO This "time to settle" is very evident when the caps are new but once they have run in, you can switch off and power it the next day without big differences.
The "time to settle" only appears again if you leave the caps off for more than a month but it tends to be shorter.
I can leave my CDP off for 7 days and it gets back to normal in 1 hour after turn on
The "time to settle" only appears again if you leave the caps off for more than a month but it tends to be shorter.
I can leave my CDP off for 7 days and it gets back to normal in 1 hour after turn on
This sounds like reforming of the insulation layer.
I wonder if some types of electrolyte dissolve the insulating layer and need to be reformed at each power up.
hello i`m new here and a noob ,so please bear with me.
I want to build a power supply for the project97 preamp.
So i`m going to need +/-15V at about 100-150mA if i`m not wrong.
My transformer delivers +/-40 Vdc.
What version would be the best in this case and what values need changing for the new input/output voltages?
Thanks for your patience and i hope i didnt annoy you guys too much
I want to build a power supply for the project97 preamp.
So i`m going to need +/-15V at about 100-150mA if i`m not wrong.
My transformer delivers +/-40 Vdc.
What version would be the best in this case and what values need changing for the new input/output voltages?
Thanks for your patience and i hope i didnt annoy you guys too much
You got to RC filter/drop your input voltage to 25V first. Then read that guide:
http://www.diyaudio.com/forums/power-supplies/153484-using-hypnotize-general-shunt-reg-pcb.html
I prefer simple and passive. Just use dropper power resistors. 10W loudspeaker style. The values are going to depend on where you will set the CCS. With 40V input, the regs will not have problems, its either you prefer to dissipate the extra on the CCS input Mosfet or RC prefilter. One is less impedance & more sinking, the other is more filtering. I would lean towards the former if you have some sink area. 15V @ 200mA is 3W. 7.5W total on the CCS. Not terrible.
V1 info needed
Hi Salas,
I am going to build your shunt version 1, as posted in the first thread.
Since I am out of 2SK170GR for Q5, I would like to ask you an advice on substituting it with 2SK117GR: it has the same low VGS(off), lower Ciss but it is more noisy.
Another question is about C1-2-3: after reading all the threads, looks like you suggest low to medium ESR caps for C1-2, while C3 should be the best, in ESR, one can afford. However HiFiNutNut reported oscillation when using a 470microF Rubycon ZL, that has a low ESR of 0.038 ohm. http://www.diyaudio.com/forums/power-supplies/143693-simplistic-salas-low-voltage-shunt-regulator-146.html#post1959931
Summing up, what do you use for C1-2-3, in terms of ESR?
Thank you very much for your help.
Hi Salas,
I am going to build your shunt version 1, as posted in the first thread.
Since I am out of 2SK170GR for Q5, I would like to ask you an advice on substituting it with 2SK117GR: it has the same low VGS(off), lower Ciss but it is more noisy.
Another question is about C1-2-3: after reading all the threads, looks like you suggest low to medium ESR caps for C1-2, while C3 should be the best, in ESR, one can afford. However HiFiNutNut reported oscillation when using a 470microF Rubycon ZL, that has a low ESR of 0.038 ohm. http://www.diyaudio.com/forums/power-supplies/143693-simplistic-salas-low-voltage-shunt-regulator-146.html#post1959931
Summing up, what do you use for C1-2-3, in terms of ESR?
Thank you very much for your help.
May I suggest using the Panny FM series, and parallel 2-4 of them for both low ESR, DF, etc. and ripple rejection.
Try to NOT go over 50uf for C1... IF, C1 is after the FWBR.
Some folks use passive smoothing filtering (CLC or CRC) after the bridge, then use the Salas shunt/ccs.
Wheeze
2SK117 is OK. The main noise is the Vref element, will die out a lot with a 1000uF cap across. I suggest you use both a 2SK load on the BJT and a Jfet CCS tail for the main CCS control element. Don't worry about oscillations in V1.0, that one in the link had a buffer mod that made it much more demanding for optimum layout and dampening parasitics.
Thanks Salas,
the 1000uF cap is C2, right? I noticed that in post 1 schematic, C2 value is 100uF, while in your PDF (Salas RIAA PDF V1) it's value is 1kuF: which value is right/better? I probably use Disco PCB, and will use 2sk170BL for Q2-Q6, which I have plenty.
I was reviewing the zener (1N47xxA) datasheet: the glass type is preferred since it's less noisy (compared to the plastic one), but would be advantageous to use the BZX85C type which have a slight lower Zzk and leakage current?
Wheezer, please tell me what is FWBR? I couldn' find the meaning.
Post one is before some optimizations that took place in its evolution. BZX85C looks like a better choice. Low impedance means 1000uF bypass both for cleaning the noise and keeping the phase flat in the very lows.
Hi Wheeze,
I am not getting what you said about C1 position: in the usual PSU, we have a transformer, then a FWBR, then filtering (capacitative, inductive). In this last stage is possible, as you said, to use an inductor or a resistors to improve the filtering.
The voltage coming out from all above, supplies the Salas regulator in which is present C1: you said "IF C1 is after the FWBR", but I don't understand where else it could be....
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.