Author Topic: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315  (Read 29418 times)

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Offline broderp

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #50 on: December 13, 2016, 10:20:47 am »
No activity for some time, this was very interesting... :(

What happened?  Did the project go bust?
 

Offline Vgkid

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #51 on: February 17, 2017, 05:09:14 am »
Looks like UA hasn't updated this in a year and 4months so I guess it died.
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Offline Dwaine

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #52 on: February 17, 2017, 05:20:11 am »
It's a shame.  I was really looking forward to this project completing.   It would of been nice to have and LCR/ESR bench meter....

 
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Offline unitedatoms

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #53 on: November 19, 2018, 04:57:13 am »
Sorry for disappearance, I am back. I rethought everything about this project.
This time will start with enclosure. My current choice is Makersled heatsink slim black aluminum.

http://www.makersled.com/wp-content/uploads/2015/10/MakersSLIM-Get-Mounting-Your-LEDs.png

ordered 2x kits for 30$ each, 12" long. The choice of enclosure is for possible vesa mounting, for incremental build with multiple small boards, multiple front panels like in euro racks, so it will be possible to add small parts of project incrementally.

Dec 08 2018:
Built the power supply stage.
12V 1.5A
« Last Edit: December 09, 2018, 04:54:36 am by unitedatoms »
Open Hardware DIY Kit LCR/ESR Impedance meter UA315
 

Online OwO

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #54 on: February 21, 2019, 08:19:26 pm »
I still don't quite get why the design is so complex. It isn't difficult to filter a power supply to >100dB isolation especially at these lower frequencies (last time I needed 100dB isolation at 2.5+ GHz a shield can, careful layout design, and a few stages of ferrite-capacitor filtering was all that's required). Passive filtering takes care of the higher frequencies and for the lower frequencies you just need a linear regulator with high PSRR like the SGM2028. I also don't quite get your description of why supercapacitors are needed; are there very sensitive components that need a specific power off sequence?
Hewwo, w-welcome to OwOComm headqwarters, yuw can call me Gabwiel! UwU It's abowt time I intrwoduce yuw to a-an exciting worrld ow commuwnication systwems!
 
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Offline unitedatoms

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #55 on: February 21, 2019, 11:34:48 pm »
Agree. It is too complicated.

One day I saw that supercaps are cheap. And it was the original cause.

I chose supercapacitors because I had inertia of thinking over some radio circuits phase noise and low noise DC. It looked for me that noise wise that capacitors are better than batteries, batteries are better than photoelements, photovoltaics are may be better that references inside the linear supplies, etc.

The hypothesis was DSP wise, that DC source noise is a phase noise of Zero's Hz generator.

So by not looking at role of noise in ratiometric AC I overbuilt the noise defenses.
It is "volt nuts" in bad way. Or design rabbit hole.

I had so many mistakes. But I am glad I that I tried. I still have better ideas to continue all over.
One idea is to overcome few limitations of this DSP chip and use semi-analog approach in phase detector to reach super high resolution on phase.

Instead of digital multiplier, use MDAC four quadrant kind, and go to low MHz. May be up to 10MHz with no FPGA or even DSP.
« Last Edit: February 21, 2019, 11:49:17 pm by unitedatoms »
Open Hardware DIY Kit LCR/ESR Impedance meter UA315
 

Online OwO

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #56 on: February 22, 2019, 02:03:34 am »
I chose supercapacitors because I had inertia of thinking over some radio circuits phase noise and low noise DC. It looked for me that noise wise that capacitors are better than batteries, batteries are better than photoelements, photovoltaics are may be better that references inside the linear supplies, etc.
Actually this is a good point, a supercap is probably a easy way to get a lower noise floor at the <100Hz region than the best low noise LDO you can get (provided the cap is big enough that the voltage rolloff doesn't start becoming noticeable).

One idea is to overcome few limitations of this DSP chip and use semi-analog approach in phase detector to reach super high resolution on phase.

Instead of digital multiplier, use MDAC four quadrant kind, and go to low MHz. May be up to 10MHz with no FPGA or even DSP.
I would still go with a DSP based solution, maybe just two ADCs feeding a FPGA like all the open source VNA designs out there these days...

If you are only dealing with <10MHz measurements you can directly digitize the AC signals, then do everything in the FPGA. The full system could just consist of the FPGA, a DAC, 2 ADCs (one for voltage and one for current), and some amplifiers.
« Last Edit: February 22, 2019, 02:10:08 am by OwO »
Hewwo, w-welcome to OwOComm headqwarters, yuw can call me Gabwiel! UwU It's abowt time I intrwoduce yuw to a-an exciting worrld ow commuwnication systwems!
 


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