The simplistic Salas low voltage shunt regulator - Page 102 - diyAudio
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Old 20th August 2009, 05:27 PM   #1011
iko is offline iko  Canada
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Tham, any updates?
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Old 21st August 2009, 12:47 AM   #1012
jkeny is offline jkeny  Ireland
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Tham, I'm also interested to hear about this as I too want to power a Tripath TA2020 amp and test out both the Salas shunt reg & Ikoflexer's microprocesser control circuit on it (when ready)

I'll be putting it up against some LiFePo4 high current delivery batteries which I have yet to hear on a power amp.
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Old 21st August 2009, 12:54 AM   #1013
Salas is online now Salas  Greece
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If it does the same it did with the Riaa and Marinos OPA627 line stage at 200mA setting, then it will be better than batteries. I have compared personally.
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Old 21st August 2009, 01:08 AM   #1014
jkeny is offline jkeny  Ireland
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Salas, these 3.3V batteries are high current delivery but small (60 Amp continuous & 120 Amp 10 sec burst), low impedance 4-8 mOhm & retain their power delivery right up to full discharge. Heavily used by the remote control aficionados for flying machines due to their weight to power ratio & their lifetime. The only unknowns are noise & how they sound powering amps (I got them for powering DACs, etc.)

Have you tried these?

Last edited by jkeny; 21st August 2009 at 01:11 AM. Reason: more info
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Old 21st August 2009, 01:30 AM   #1015
iko is offline iko  Canada
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At that output impedance it will have a hard time to beat the regulator, especially in a power amp. And they better be able to provide sub 200uV noise too. Let us know what you find out.

Edit: of course, this is just armchair speculation on my part.
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Old 21st August 2009, 01:36 AM   #1016
Salas is online now Salas  Greece
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Quote:
Originally Posted by jkeny View Post
Salas, these 3.3V batteries are high current delivery but small (60 Amp continuous & 120 Amp 10 sec burst), low impedance 4-8 mOhm & retain their power delivery right up to full discharge. Heavily used by the remote control aficionados for flying machines due to their weight to power ratio & their lifetime. The only unknowns are noise & how they sound powering amps (I got them for powering DACs, etc.)

Have you tried these?
They seem special. If it beats them it will be no mean feat. Will not up their impedance if you need to chain 4 of them? Build Iko's V1.5 evolution of the shunt since it worked for Tham without weird interactions as V1 did also. It has a performance edge.

http://www.diyaudio.com/forums/showp...&postcount=857
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Old 21st August 2009, 01:43 AM   #1017
jkeny is offline jkeny  Ireland
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Ikoflexer, I know that these shunt regs simulate < 1 mohm but how does this translate in the real world - have they been measured at the output of the reg?

I know this isn't the complete quality measure of a power source & I don't know, for instance how the batteries perform up through the frequencies. It might be like in the LM317 thread that flat impedance Vs frequency might be more a determinant of sound. Noise also would be the major worry with batteries - I've no way of measuring this - any suggestions?

Edit: Yes Salas, I was going to start with V1 but I need to re-read Tham's posts when I start the build & if V1.5 isn't much more complicated then that will be the one

I don't mean to be putting a damper on your reg by doing this just evaluating the various options. And with batteries there's tha added complexity of monitoring low voltage & chargers, etc.

Thank you for being so gracious in considering these - many designers have a "my baby is the bestest ever" attitude

Last edited by jkeny; 21st August 2009 at 01:54 AM.
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Old 21st August 2009, 01:48 AM   #1018
Salas is online now Salas  Greece
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It takes HP equipment to really know everything in a practical reg build. And if its built then it can be put on the road anyway. It will reveal itself doing its actual job. Most practical evaluation of all IMHO.
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Old 21st August 2009, 02:07 AM   #1019
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There are two simple tests for the output impedance. You won't get any journal papers published with either of them, but it will allow you to compare two different sources. You'll need a sine generator for this. There are several sine signal generator solutions freely downloadable if you don't have a HW one. You also need a high current n-channel mosfet, which will be the load. One 10k resistor across G-D and a variable resistor of 10k across the G-S pins. Set the variable resistor to about 500R initially. Apply the sine signal through a capacitor of about 4uF to the gate of the mosfet. Then connect the drain of the mosfet to the regulated output, and the source of the mosfet to ground. As you increase the resistance of the variable resistor across G-S, the mosfet will pass more and more current. I usually don't apply the sine signal until I get the current I want through the mosfet. The mosfet should have a good heat sink.

Then you use the AC setting of your DMM to measure the regulated output. I find it best to look at it with the oscilloscope. The smaller the AC on the output, the lower the output impedance is. I do this usually for a few frequencies of interest: 500Hz, 1kHz, 3kHz, 5kHz, 10kHz, 15kHz, 20kHz.
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Old 21st August 2009, 02:14 AM   #1020
jkeny is offline jkeny  Ireland
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Ikoflexer, thanks for the technique. Has anyone done this on a built regulator? The battery impedance is a from the published spec sheet & laboratory tests (actually spec sheets say 8mohm but lab results give 4 mohm)

Any idea how to measure noise output?
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