Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Equipment & Tools From test equipment to hand tools

DIY Audio Analyzer with AK5397/AK5394A and AK4490
DIY Audio Analyzer with AK5397/AK5394A and AK4490
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 26th March 2019, 03:24 AM   #2641
1audio is offline 1audio  United States
diyAudio Member
 
Join Date: Mar 2004
Location: SF Bay Area
I was wrong, but not by much. I just checked with an HP3428 milliOhmmeter and a 20 AWG copper wire at room temperature 20 MM long is 1 milliOhm. The HP uses AC to make the measurement and measures only the real part of the resistance. At these low levels DC errors can dominate the measurement which is why its AC. Yopu could use the 2 CM of 20 AWG wire as a test for the system.

Even with a proper kelvin connection I doubt the active circuit can be that low across that band. The inductance would dominate pretty quickly as I have discovered to my dismay. I built a 100 dB 50 Ohm attenuator that used .5 milliOhms of wire for the output resistance. Turns out a straight wire in that form will have enough inductance to get an HF boost which made for problems verifying an RIAA network. It was an interesting learning experience.
__________________
Demian Martin
Product Design Services
  Reply With Quote
Old 26th March 2019, 05:08 AM   #2642
xx3stksm is offline xx3stksm  Japan
diyAudio Member
 
xx3stksm's Avatar
 
Join Date: Jun 2017
Location: Hokkaido(north area)
DIY Audio Analyzer with AK5397/AK5394A and AK4490
As long as I have checked, 10A fuse for battery protection is 10 milliohms, and a connector capable of 10A is about 20 milliohms or more. Total DC resistance with wire from a battery to the power amplifier can't be less than 50 milliohms. Battery impedance itself is usually neglectable. FET impedance is easily less than a connector even if you use a small one(2sj130). I'm sure the dominating factor is wire.
  Reply With Quote
Old 26th March 2019, 05:19 AM   #2643
xx3stksm is offline xx3stksm  Japan
diyAudio Member
 
xx3stksm's Avatar
 
Join Date: Jun 2017
Location: Hokkaido(north area)
DIY Audio Analyzer with AK5397/AK5394A and AK4490
2sj130 is incorrect. SSM3J130(UFM package) is correct. Two SSM3J130 is 12milliohms at 2.5A.
  Reply With Quote
Old 26th March 2019, 11:02 AM   #2644
lemon is offline lemon  Greece
diyAudio Member
 
Join Date: Apr 2009
The "Power Supply Output Impedance Measurement" on MI-Pro contains a sample device test plan which can be used to measure the power supply output impedance in a frequency range from 1Hz to 100kHz at a step of 1/3 octave. It contains three Panel Setting Files (PSF) and one DTP file.
Three PSF files are thus created for 1Hz~10Hz (10s), 10Hz~100Hz (1s), and 100Hz~100kHz (100ms) respectively. They are:

1. PowerSupplyOutputImpedanceMeasurement10s.psf
2. PowerSupplyOutputImpedanceMeasurement1s.psf
3. PowerSupplyOutputImpedanceMeasurement100ms.psf

I can't see what these files contains inside but from the .dtp file that loaded into Device Test Plan, I can't see something special that compensate the length of cabling

Code:
1
Editable
16
Step,
Description,
Instruction,
Duration(s),
Delay(s),
A-Waveform,
A-Frequency(Hz),
A-Amplitude(V),
B-Waveform,
B-Frequency(Hz),
B-Amplitude(V),
PhaseDifference(D),
A-DC(V),
B-DC(V),
Impedance(Ohms),UDDP1(UU)
Phase(Degree),UDDP2(UU)
1,Displaytitleon{[Panel3]},LOG,PowerSupplyOutputImpedanceTest,,,,,,,,,,
2,Displaysubtitleon{[Panel1]},LOG,1Hz~100kHz,,,,,,,,,,
3,Initializethestartingoutputfrequency:0.976562498Hz,OPT,x1,=0.976562498,,,,,,,,,
4(REPEAT),Displaythecurrentoutputfrequencyinpurpleon{[Panel2]'255,0,255'},LOG,,x1,Hz,,,,,,,,
5,Ifoutputfrequency<10Hz,gotosteplabelled(1HZ),CHK,x1,<,10,(1HZ),,,,,,,
6,Ifoutputfrequency<100Hz,gotosteplabelled(10HZ),CHK,x1,<,100,(10HZ),,,,,,,
7,Ifoutputfrequency<=100000Hz,gotosteplabelled(100HZ),CHK,x1,<=,100000,(100HZ),,,,,,,
8,Jumptosteplabelled(END),JMP,(END),,,,,,,,,,
9(1HZ),LoadPanelSetting(1Hz<=outputfrequency<10Hz),LDP,psf\PowerSupplyOutputImpedanceMeasurement10s.psf,,,,,,,,,,
10,Outputthecurrentfrequencyandsampleitattheinputsimultaneously,SIO,12,0,01,x1,10,01,x1,10,0,0,0
11,Increaseoutputfrequencyby1/3octave:2^(1/3)=1.25992105,OPT,x1,*1.25992105,,,,,,,,,
12,JumptoStep(REPEAT),JMP,(REPEAT),,,,,,,,,,
13(10HZ),LoadPanelSetting(10Hz<=outputfrequency<100Hz),LDP,psf\PowerSupplyOutputImpedanceMeasurement1s.psf,,,,,,,,,,
14,Outputthecurrentfrequencyandsampleitattheinputsimultaneously,SIO,2,0,01,x1,10,01,x1,10,0,0,0
15,Increaseoutputfrequencyby1/3octave:2^(1/3)=1.25992105,OPT,x1,*1.25992105,,,,,,,,,
16,JumptoStep(REPEAT),JMP,(REPEAT),,,,,,,,,,
17(100HZ),LoadPanelSetting(100Hz<=outputfrequency<=100000Hz),LDP,psf\PowerSupplyOutputImpedanceMeasurement100ms.psf,,,,,,,,,,
18,Outputthecurrentfrequencyandsampleitattheinputsimultaneously,SIO,0.2,0,01,x1,10,01,x1,10,0,0,0
19,Increaseoutputfrequencyby1/3octave:2^(1/3)=1.25992105,OPT,x1,*1.25992105,,,,,,,,,
20,JumptoStep(REPEAT),JMP,(REPEAT),,,,,,,,,,
21(END),End,END,,,,,,,,,,,
#
1936,1056,96,96
1,1,7,1025,30,230
0,0,0,0,0
1,1.000000,100000.000000,0.000000,2.000000,6,14,1,0,1,0,0,0,0,0,0,7f,7f7f,7fff,ffff,7f7fff,2,1030,229,619
,
,
,
,
,
,
,
,
,
,
1,1.000000,100000.000000,-180.000000,180.000000,6,15,1,0,1,0,0,0,0,0,0,7f,7f7f,7fff,ffff,7f7fff,2,1030,611,1000
,
,
,
,
,
,
,
,
,
,
0,0.000000,1.000000,0.000000,1.000000,0,0,0,0,1,0,0,0,0,0,0,7f,7f7f,7fff,ffff,7f7fff,0,0,0,0
,
,
,
,
,
,
,
,
,
,
0,0.000000,1.000000,0.000000,1.000000,0,0,0,0,1,0,0,0,0,0,0,7f,7f7f,7fff,ffff,7f7fff,0,0,0,0
,
,
,
,
,
,
,
,
,
,
0,0.000000,1.000000,0.000000,1.000000,0,0,0,0,1,0,0,0,0,0,0,7f,7f7f,7fff,ffff,7f7fff,0,0,0,0
,
,
,
,
,
,
,
,
,
,
0,0.000000,1.000000,0.000000,1.000000,0,0,0,0,1,0,0,0,0,0,0,7f,7f7f,7fff,ffff,7f7fff,0,0,0,0
,
,
,
,
,
,
Then, the Zo calculate from the formula: UDDP1 (Impedance): 1*[f1RMS_A(EU)]/[f1RMS_B(EU)].
RMS_A(EU) and RMS_B(EU) are total RMS values calculated by the oscilloscope. f1RMS_A(EU) and f1RMS_B(EU) are the RMS values of the highest peak frequency calculated by the spectrum analyzer (therefore nearly all noises are excluded).

I am not expert about all these, of course more information Virtins could be share with us...

The diagram that I used for the Zo measurement is attached.
The AC injection is always the 10-15% of PSU Load, ie 100mΑ testing load = 10-15mA of AC input signal.
Attached Images
File Type: png SE RTX diagram.png (44.7 KB, 196 views)
  Reply With Quote
Old 26th March 2019, 11:08 AM   #2645
jan.didden is online now jan.didden  Europe
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Westende Resort, BE coast
That measurement setup seems sensible. I know from experience that you can reliably measure below 1mOhm, but only at lowish frequencies. The impedance will invariably rise above a few kHz due to drop in loop gain of the error amp.

I would do it slightly differently; I would insert a controlled current into the output and then measure the residual, using Ohm's law to calculate Zout. Not using the 1 Ohms as reference, so any connection-resistance that would add to the 1 Ohms have no effect.
For instance, there are two currents flowing in the ground connection between the 'bottom' of the DC load and the ground point of the measurement probes; one current from the load, one from the 1 Ohms. So do these currents add, or subtract? It is a confounder.

Jan
__________________
Cable: a potential source of trouble interconnecting two other potential sources of trouble - Erik Margan
Linear Audio pubs and articles . The SilentSwitcher now at diyaudio store SilentSwitcher. Keeping in touch with SY.

Last edited by jan.didden; 26th March 2019 at 11:15 AM.
  Reply With Quote
Old 26th March 2019, 01:13 PM   #2646
1audio is offline 1audio  United States
diyAudio Member
 
Join Date: Mar 2004
Location: SF Bay Area
If you are using the single ended output you need to be sure there is no hiddent parallel ground path. remove the 1 ohm resistor and measure the DCR between the marked ground and the BNC shell on the RTX. The BNC is tied to power ground I believe to meet safety requirements.
__________________
Demian Martin
Product Design Services
  Reply With Quote
Old 26th March 2019, 01:16 PM   #2647
lemon is offline lemon  Greece
diyAudio Member
 
Join Date: Apr 2009
- Sure, this setup goes reliable to the lower frequencies against to the high upper frequencies.
- The inserted AC stimulus current is controlled by the software, you can change each time the amount of AC current (at the .dtp file) that inserted at the output.
- I don't know the exact role of 1 Ohm resistor. I think, that this is a common diagram to many related documents. Usually, they insert a transformer at the signal output to break any continuity. I don't use any transfo, but I care to lift any power gnd from my measurement setup, usually (to break any gnd loops).
- The 200K ADC input and the differential input measurement, are the positive of this setup and probably minimized the effect of cable length.
  Reply With Quote
Old 26th March 2019, 01:23 PM   #2648
lemon is offline lemon  Greece
diyAudio Member
 
Join Date: Apr 2009
Quote:
Originally Posted by 1audio View Post
If you are using the single ended output you need to be sure there is no hiddent parallel ground path. remove the 1 ohm resistor and measure the DCR between the marked ground and the BNC shell on the RTX. The BNC is tied to power ground I believe to meet safety requirements.
Demian, I remember that the same you have told me before...to the "GB for Virtins MI Pro for RTX6001 autoranging/autoscaling & for soundcard end users" thread.
For this reason, I have made a lift gnd on AC sockets that connects the RTX, Electronic Load and Lab PSU.
Each time that I have to measure a Zo or PSRR on a PSU, I lift the gnd from these AC-sockets.
  Reply With Quote
Old 26th March 2019, 02:12 PM   #2649
1audio is offline 1audio  United States
diyAudio Member
 
Join Date: Mar 2004
Location: SF Bay Area
The 1 Ohm resistor is the current sampling point. You are measuring the voltage across it as representative of the current into the load (Va). The voltage across the load (Vb) is the other part of the equation. The amplitude and phase relationship converts to the impedance in VI, Vb (E)/Va (I)= R. You should check the resistance R with a meter to make sure that it is 1 Ohm in circuit and that you are measuring differentially. Testing a reference resistor of around the same value is very helpful in validating the measurement.
__________________
Demian Martin
Product Design Services
  Reply With Quote
Old 26th March 2019, 04:56 PM   #2650
lemon is offline lemon  Greece
diyAudio Member
 
Join Date: Apr 2009
The resistor has measured by a DEREE LCR meter and is 0.999-1.000 Ohm

The diagram as told before is the following:

Click the image to open in full size.

The attached photos are the connection on PSU output for Zo measurement and a photo of cable with the connectors.
Attached Images
File Type: jpg Zo connection.JPG (413.4 KB, 134 views)
File Type: jpg Zo connection cable.JPG (348.8 KB, 128 views)
  Reply With Quote

Reply


DIY Audio Analyzer with AK5397/AK5394A and AK4490Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
New AKM Stereo ADC AK5397 announced JensH Digital Source 20 24th December 2014 12:05 PM
New AKM Stereo ADC AK5397 ??? HpW Equipment & Tools 6 16th May 2014 04:26 PM
NTi Audio XL2 Handheld Audio Analyzer Fredenando Equipment & Tools 0 18th April 2010 03:04 AM
AKM AK5394a TobWen Digital Source 41 31st December 2003 06:18 PM


New To Site? Need Help?

All times are GMT. The time now is 07:32 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki