The simplistic Salas low voltage shunt regulator

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Electrolyte capacitors in conjunction with a Salas low voltage shunt regulator.

Hello,

I have a question about electrolyte capacitors in conjunction with a Salas low voltage shunt regulator.
What are the experiences with electrolyte capacitors which brands are good for this situation?

I know that electrolyte capacitors in the power supply of a DAC or CD transport it changes very much in sound quality. (for example Blackgate FK and Blackgate STD)

Is this also for low voltage shunt regulators?

Rudy
 
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If you have use BG, alternative in order of preference: Jensen 4 pole, Nichicon KG super trough & BHC slit foil.

I did not experiment with BG so I can not comment.

Relative to the others I prefer the Jensen 4 pole due to it´s superior trebble performance.

Nichicon KG produces very good bass with subtle highs.

These caps can be used to tune the overall tone but are not as effective as the Vref or output caps on the shunt.
 
Hi,

I have 5W class A power amp regulated with LM317. I would like to leave LM317 in because I would then have to disassemble lots of parts (much time consuming) so I was thinking to convert LM317 as CCS and add with Salas shunt circuitry. Would that gain noticeable benefit over single LM317 series regulator?
 
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In most cases people report they prefer discrete shunts subjectively over common chip regs. 317T is not for a great CCS but it can make do. Its simple, just one resistor from out to adj pin. You would have to use just the shunt circuit portion of V1.0 after it. I.e. no 9610 no leds no R1 no jfet for leds.
 
during which operating conditions is the current draw 200mA?
Are there any operating conditions when the current draw from one or other supply rail is less than 200mA?
Are there any operating conditions when the current draw from one or other supply rail is more than 200mA?

200mA for a T-Amp? Maybe just at cruising level for the 15W model. Use a current meter in series with your now supply and play at full tilt tracks with strong dynamic range on your most difficult loudspeakers. Register medium and peak current draw and then set the reg +20% peak. All the excess above median SPL current draw will be constantly burning at no peaks time on the output Mosfet's sink times Vout, while all the available current will be burning on the input CCS sink times Vin-Vout. Draw your wattage and sinking needs from that. HOT. External sinks for sure. The resistor that needs to be reviewed for Wattage rating is R1. It must hold what voltage you will measure across it (around 2V ballpark) times the full current set. Choose X3 that for its rating so it stays reliable in the long run. Yes, you can use 22V but be economic with Vin-Vout if you will end up at some high current setting because every spare Volt will kick up CCS heat dissipation.

Sorry to fuse you as I did not state clearly on my original post.

I would like to use this shunt regulator on the QA550 SD card player, not a T-amp. It is because the 12.6V output voltage fit the application.
 
Hi Salas
I would like to try your shunt regs with some digital ICs requiring very low voltages, such as 3.3V and 1.8V. I can rely on Vin 12V. Current will be set at 200mA, roughly twice the load.
My idea is to use an IRF9610 for the CCS and a BD140 (with 10 Ohm base stopper) for the shunt device. You recently addressed other members asking for a 5V version to the latest V1.2R (post #3200), but unfortunately I don’t have space enough for a couple of huge 4.7uF PP, thus I was thinking to implement the V1.0 schematic with remote sensing, eventually using the latest cascoded jfet CCS rather than the old one with leds.
For Vref I’m planning to use a 2SK170 instead of 2N5457 as, if I recall correctly, you stated it performs better with digital.
Any suggestion?
 
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The K170 instead of the 5457 is suitable active load for under 5Vout because it has lower pinch off and works better under those low margins between Vo-Vbe. 2N5457 has better bandwidth where the voltage margin suffices but this is not in question here since the BJT output necessary for under 5Vout is lower open loop gain and bandwidth by much VS the Mosfet. See also for MJE15031 if for TO-220 in output. Although the BD140 will hold fine for dissipation, circa 100mA region is going to be curvier for hfe. Better if you got a grey plastic original Philips. Much more fT than from other manufacture but more rugged ones. Lastly as you don't have to battle high voltages so for the cascode to double as a higher Vmax and dissipation element, I would recommend you keep it simple with Leds and 2N5457 at their tale (25VmaxDS) or BF245A which are both high frequency. See the simulated PSRR curve.
 

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Thank you Salas.
BD140: I've got some NOS grey plastic TFK... not Philips, but similar

So you recommend the simple CCS with 9610, grid stopper 220 ohms, 3 green leds Vf 1.8, 2N5457 (got some old Motorola's) with GS tied togheter and 100 ohms to gnd, right? No "zobel" RC across the leds.

Value for Vref cap: 100-200uF? Vout cap: 47-100uF (I have some OsCon 100uF)? Possibly bypassed with 0.01-0.1 uF MKP the first, no bypass on the second one, correct?

I forgot to mention that the digital board has some LC filter close to each IC: smd inductor + bypass cap 0.1uF (now ceramic, but I can replace them with very tiny MKS 2.5 mm pitch). Do they hurt?
I can eventually remove the inductor as the new supply should be clean enough and "dedicated" (one PS for each IC), but probably is safer to keep the cap very close the VDD pin as suggested in every datasheets.
Or I can even remove this cap and place Vout cap on the digital board. At that point the cap will be 5 cm, maybe less from the shunt device. Too far from it?

P.S. I found some very good 4.7uF/250V PP caps from Icel (PPB series, equivalent to Wima MKP10) for pennies. Too huge for this project! (footprint 42 x 22 mm). As soon as I'll come to Greece, I send you some samples. ;)
 
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Thank you Salas.
BD140: I've got some NOS grey plastic TFK... not Philips, but similar

So you recommend the simple CCS with 9610, grid stopper 220 ohms, 3 green leds Vf 1.8, 2N5457 (got some old Motorola's) with GS tied togheter and 100 ohms to gnd, right? No "zobel" RC across the leds.
Yes, that graph was from that scenario. No 100R.

Value for Vref cap: 100-200uF? Vout cap: 47-100uF (I have some OsCon 100uF)? Possibly bypassed with 0.01-0.1 uF MKP the first, no bypass on the second one, correct?
Correct.

I forgot to mention that the digital board has some LC filter close to each IC: smd inductor + bypass cap 0.1uF (now ceramic, but I can replace them with very tiny MKS 2.5 mm pitch). Do they hurt?
I can eventually remove the inductor as the new supply should be clean enough and "dedicated" (one PS for each IC), but probably is safer to keep the cap very close the VDD pin as suggested in every datasheets.
Or I can even remove this cap and place Vout cap on the digital board. At that point the cap will be 5 cm, maybe less from the shunt device. Too far from it?
Output cap should be very near to reg's output BD140 across the force lines. Inductance, what value that SMD coil can be? We can simulate its impact.


P.S. I found some very good 4.7uF/250V PP caps from Icel (PPB series, equivalent to Wima MKP10) for pennies. Too huge for this project! (footprint 42 x 22 mm). As soon as I'll come to Greece, I send you some samples. ;)
Thanks!
 
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See if it oscillates with or without it in the power path on the oscilloscope by checking the power line when you will apply the reg. Jumper it or not. If its stable always, then listen if it makes any preference to you with or without. Normally the shunts don't like inductance. But there is a chance those chips like it.
 
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