Author Topic: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315  (Read 25513 times)

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Offline unitedatoms

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OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« on: August 07, 2015, 06:38:12 am »
I am excited to share with All my Impedance Meter project.
It is named UA315 Open Source Hardware LCR/ESR Impedance Meter. It can be either DIY benchtop kit or completely built.

The thread is being updated in real time as the project progresses

Blog posts, design articles, detailed info, (WARNING: picture of cute dog :))

Voting thread
Please add your vote to help me to understand what pricing can be!

Device description
It measures Immitance parameters: Impedance ( Resistance and Reactance ), Admittance (Conductance and Susceptance ). Capacitance, Inductance, Equivalent Series Resistance (ESR), Q value, D factor, Phase angle / Loss angle and Loss Angle Tangent in range of frequencies 10Hz to 100KHz (with possibility to reach 200KHz, but it is yet to be seen).



The project is about 50% done and I will keep posting schematics and code as I go.
The digital board is Arduino(TM) alike:

The analog-to-digital board is in progress. Waiting for first 5 analog-to-digital board prototypes to arrive so I could tune the custom made transformer details.

The Analog to digital board schematics:


There are 2 boards.
Digital board is 75+ parts.
Analog board is ~220 parts.
Also included parts:
- probe
- internal flat cable 34pin
- power connector
- enclosure with fasteners


The brief description of how analog-to-digital board works:
- The AD5933 is single bin Fast Fourier Transformer with Direct Digital Synthesizer used as magnitude and phase sensor.
- The excitation signal is buffered with op amp wired as phase-error reduction amplifier (p.314 of Art of Electronics 3rd ed.) also summing DC offset to provide DC bias to device under test
- Kelvin probe and device under test have current limited by output impedance of a buffer.
- The sense V of D.U.T. and reference resistor is scaled by instrumentation amplifiers
- V and I signals from instrumentation amplifiers are multiplexed and brought to AD5933 input through V-to-I resistor, since AD5933 accepts only current input.
- The data about amplitude and phase both for V and I is processed by Arduino-alike board and displayed to user.

Brief extra details, why the parts count is high:
- Major effort is done to reduce the noise of power supply
- All clocking of every chip is fed from single master clock generator with muxed dividers
- The power supply is supercapacitors banks (graphene based!) which supply power during controlled shutting off of the step-up DC-DC converter
- The power during measurement phase (from few milliseconds up to 1 sec at 10Hz range) is regulated with linear regulators, there is no switching, transitions or power source disturbing software activity is happening during measurement phase
- The external power is isolated to >100-120 Db during measurement phase
- The relays are latchable and are not powered during measurement, so the contacts resistance is not modulated by coil current fluctuations
- The method, algorithm and implementation is done with care to avoid reliance on absolute voltage
values. The design is completely ratiometric, so the major contribution to accuracy is values of reference resistors.
- The DC errors like offsets instabilities, thermals are not affecting the AD5933 converter since it has narrow-band sensitive to only single frequency bin
- Having no need to avoid DC errors, the signal path has no DC blocking capacitors, it adds stability to output buffer and reduces risk of parasitic feedbacks
- Having separate I and V channels, which are measured at separate time, the geometric calculations made possible to move from analog-to-digital part and perform in software, instead of AD5933 original designs, where  measurement relies on assumption that output signal has certain phase.
- Having 2 pairs (I and V) of phase/amplitude data instead of 1 assumed pair and 1 measured, the phase accuracy measurement may exceed the one claimed in AD5933 datasheet
- Having this 2 pairs of data, the design is immune to accuracy of output buffer and does not require the buffer to become a critical part of signal path, like Howland current source, transformers, calibration or highly precise parts etc.
- Replacing I-to-V amplifier with virtual ground with simple reference resistor helps to avoid reliance on phase accuracy of I-to-V converter. Resistor is assumed to have no phase dependency of I-to-V conversion (at least in range of frequencies of interest)
- In low and middle ranges of D.U.T. impedances the probe capacitance is factored in calculations and shows the predicted behaviour.
- For high impedance and low and midrange frequencies the probe capacitance factor is also trivial.
- The only difficult range is high impedances at high frequencies. To resolve this difficulty the prototype #4 (this is 4th iteration since April 2015) has instrumentation amplifiers added. It were simple CMOS followers in prototype #3.

The code is about 25-30% ready:
It is about few hundred lines of Arduino Sketch language. It uses UTFT library. The algorithm is infinite loop repeating the measurement and display. The calculations are all straightforward without magical constants or reference values without physical unit. It is as deterministic as possible, the factored values for parasitics like probe capacitance are explicit and are introduced in understandable, easy to maintain manner.

I will publish my very raw code as soon as will complete the analog board ordered from SeeedStudio and complete the transformer design.

Update Sep 24 2015:

The digital subassemblies progress: 34 out of 50 subassemblies for 50 kits are done
The analog boards are on the way from Elecrow.

« Last Edit: October 14, 2015, 02:21:14 am by unitedatoms »
Open Hardware DIY Kit LCR/ESR Impedance meter UA315
 
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Offline DmitryL

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #1 on: August 07, 2015, 07:06:38 am »
Hmm... woud you share the device specs first ?
You know, these boring numbers, like: "xxx mOhm- yyy Mohm, zzz pF- www mF, qqq nH- ppp H... with ABC% tolerancy..., test frequencies:bla-blah..."
 

Offline unitedatoms

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #2 on: August 07, 2015, 07:14:09 am »
Yes, absolutely. The specs are preliminary, some are underspecced, some other are too ambitious. I posted it in Crowdfunding section of the forum to get the price poll. Depending on what people think about costs, I will choose most appropriate final specs. For example 0.1% 5ppm resistor is one cost, but 0.01% 2ppm is completely different price range, and so on from component to component.

Release Date:
October 2015
 
Brief Product Description:
UA315 is a reprogrammable benchtop impedance meter for frequencies up to 100KHz. It is Open Hardware and Open Source device designed for electronics enthusiasts, who make their own electronic lab devices.
 
Technical Specs (preliminary design targets):
Model Name: UA315 (revision Beta Aug 2015)
Accuracy: 0.5% or better
Resolution: 3 or more digits
Impedance range: 0.001 ohm .. 1000 MOhm
Frequency range: 10Hz .. 200KHz
Excitation AC voltage: 1V or less
Excitation DC voltage: 2.5V
Protection from input voltage: Up to 500V
Power supply port: 5V / 1A round 5.1mm DC connector with cable for USB style power supplies or any other DC power supply. (Power supply is not included with device, when sold as assembled product or kit)
Dimensions: Approx 4" x 13" x 2"

The L and C specs are yet to be decided: But very preliminary it should be.

0.1pF .. 0.1F
10nH .. 1000H

The lowest values are most difficult.
« Last Edit: August 07, 2015, 07:20:30 am by unitedatoms »
Open Hardware DIY Kit LCR/ESR Impedance meter UA315
 

Offline DmitryL

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #3 on: August 07, 2015, 07:20:53 am »
Looks nice.... tough dubious..a bit. :-/
Have you tried to apply to Agilent/whatever as a chief technical architect, just in case ?
 

Offline unitedatoms

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #4 on: August 07, 2015, 10:52:32 am »
Looks nice.... tough dubious..a bit. :-/
Have you tried to apply to Agilent/whatever as a chief technical architect, just in case ?

Ha ha. No. This project is much smaller caliber. May be at the level of "Jr. Design Engineer". If it was the Chief Architect level, I'd use custom hybrid chips and gold plated parts on sapphire ceramic substrate.
Open Hardware DIY Kit LCR/ESR Impedance meter UA315
 

Online Vgkid

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #5 on: August 08, 2015, 01:20:11 pm »
I know you are this far, but have you looked into the GenRad Digibridge series for inspiration. A million times simpler.
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Offline unitedatoms

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #6 on: August 08, 2015, 02:21:24 pm »
I know you are this far, but have you looked into the GenRad Digibridge series for inspiration. A million times simpler.

They are all simple. I chose AD5933 as 7 chips in one: DDS-DAC, Voltage reference, 2xOpAmps with PGA, ADC, DSP. It makes it super simple. Also most of older devices designs are hard to name completely trivial to reproduce. Their schematics is sure sometimes very simple, but old analog designs are full of decisions, limited but cost/labor situations of the time. Many things changed. Say the steel enclosure with high quality oven may ruin the budget today, but was cheap 30-40 years ago. On the other hand I can show 10 lines of text on single screen.

I think I watched the tear down video. It may have a nostalgia value for some. My inspiration for this device form factor is more from mid90s era of space equipment inside piloted space crafts (USSR or Nasa). I understand that some may adore segmented LEDs which are easy to read. I like larger screen with more text for debugging.

And thank you for feedback. I interpret it as issue with lack of user controlled knobs, switches, buttons. My current plan is to fully automate the ranging functions. But if I find the source for nice generic panel mount buttons, knobs, I will add it to give to user more feel of control. And most of all I hope that users will mod, brand, paint the enclosure the way they like with labels and buttons of all sorts.

Say, someone decides to make a speaker impedance meter with charting. Or audio transformer 4-wire transfer function meter. Or blood impedance meter, oxygen in water, or body fat percentage meter, or use device as chemical frontend of PC based lab, etc. The metal panel mount USB connector which can cover the cutout hole is absolutely impossible to find for sane price. So, for this iteration I gave up on adding USB and removed it from schematics and postponed the idea of making it completely extendable for first version of kit.
« Last Edit: August 08, 2015, 02:54:27 pm by unitedatoms »
Open Hardware DIY Kit LCR/ESR Impedance meter UA315
 

Online Vgkid

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #7 on: August 08, 2015, 03:46:04 pm »
Didn't mean to shoot down your idea at all. With the .10% resistors if you add in a user available way of calibrating the meter, it will be possible for most with higher accuracy bench meters to calibrate the lcr meter to much higher realms of accuracy. For examplebeing able to calibrate it by range resistors to .05% accuracy using a precision metal film/foil resistor in a low inductance/capicatance shielded fixture. But for the low frequency measurenment(best to cal at a lowish frequency eg. 1Khz) to use the values or the resistor at DC.
for further reading read up at ietlabs.
 http://www.ietlabs.com/genrad_history/historic_appnotes/
genrad 1689 manual
http://bama.edebris.com/download/gr/1689/1689%20Precision%20Digibridge.PDF
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Offline unitedatoms

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #8 on: August 09, 2015, 12:21:58 am »
Yes, the calibration will be available to users. Thank you for links. The users will have all 100% of Source Code with easy to change values of reference resistors, probe capacitance in Arduino IDE. This is the DIY kit with blank analog-to-digital board and all through hole parts to solder.

For calibrating calculations, when D.U.T is the superior accuracy resistor, say you have 1K 0.1% on board and reading the value at 1KHz of external metal foil 0.01% 1KOhm reference and see 997.075 Ohm on screen. I will provide the Open Source Open Formula procedure how to calculate the more true reference value of on-board resistor to change it in embedded software. WolframAlpha link for example.

And users will always can just change resistors themself and any other part.

The quick comparison of GenRad 1689 design vs reference AD5933 design vs my UA315 design
- I-channel: transconductance vs transconductance vs resistor
- I-channel phase factoring: unknown (software tables may be) vs none (datasheet just has 0.5 degree of angle value to characterise transconductance amp phase error, which perhaps has very good high repeatability) vs cancellation of phase error by using same transconductance amplifier twice (muxing V-vs-I-channel).
- ADC: dual slope DC vs 1MHz ADC vs same 1MHz ADC used twice
- Synchronous detection: Multiplying DAC from Sin ROM table (that is very good advantage - hard to beat, but brings DC into picture, which is costly to implement) vs DSP vs same DSP twice.
- Bandwidth narrowness: Defined by low pass filtering around dual slope vs FFT Hamming window for any frequency vs FFT Hamming windowing for selected frequencies with only integer number of test signal periods to avoid reciprocal mixing on top of Hamming windowing
- Unavoidable reciporocal mixings: unknown vs Spurs of DDS/ADC vs  Spurs of DDS/ADC
- Avoidable reciporocal mixings: unknown, perhaps a lot of care taken to avoid interferences vs no recommendation beyond foorptint example vs switching supercapacitor power supply with all possible shutdown of parts of schematics during measurement phase
- Critical absolute references: R+timebase, R+timebase, R+timebase
- Critical non-absolute but ratiometric references in detecting side: this is no-trivial to pick, since I and V channels are not identical vs Ladder or capacitor inside 1MHz ADC (on the same silicon die as DDS/DAC, which is great if thermal behaviours are taken into account, but there is no claims from datasheet) vs matching-nesness of a pair of instrumentation amps

« Last Edit: August 09, 2015, 12:50:44 pm by unitedatoms »
Open Hardware DIY Kit LCR/ESR Impedance meter UA315
 

Offline MagicSmoker

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #9 on: August 10, 2015, 10:19:28 pm »
...
Brief extra details, why the parts count is high:
- Major effort is done to reduce the noise of power supply
- All clocking of every chip is fed from single master clock generator with muxed dividers
- The power supply is supercapacitors banks (graphene based!) which supply power during controlled shutting off of the step-up DC-DC converter
- The power during measurement phase (from few milliseconds up to 1 sec at 10Hz range) is regulated with linear regulators, there is no switching, transitions or power source disturbing software activity is happening during measurement phase
- The external power is isolated to >100-120 Db during measurement phase
- The relays are latchable and are not powered during measurement, so the contacts resistance is not modulated by coil current fluctuations
...

Turning off the power supply and running from capacitors or batteries to achieve a low noise floor is probably rendered moot by Johnson/thermal noise elsewhere. I would first try a decent toroidal mains transformer with two stages of linear regulators - perhaps in a separate metal sub-enclosure - before going crazy with the graphene supercaps and worrying about contact resistance modulation from relay coil current fluctuations (that has to be a 3rd order effect, anyway!?!).

But it otherwise sounds like you've given the design a lot of thought whereas I am glibly making a quick comment on a forum...

EDIT: this thing is quite close to being a proper (low frequency) vector network analyzer; it just needs to sweep the frequency and display the amplitude and phase response on that lovely graphical LCD panel. That would put it well above the capability of the typical handheld LCR meter (like my B&K 879B).
« Last Edit: August 10, 2015, 10:23:40 pm by MagicSmoker »
 

Offline unitedatoms

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #10 on: August 10, 2015, 11:08:42 pm »
Yes. The goal is to reach pure Johnson noise floors and thermal/aging drifts and be done with it.

Thank you for pointing out the possible powering from AC. I did it for my personal prototypes, but I decided to remove AC power source from kit for many reasons. There is a reserved 100x100x40mm unoccupied volume inside the box for those who decide to add their own modules, power supplies included. And AC source has great advantage, when zero cross detection is used to sync measurement to 50/60Hz mains for higher repeatability.

I also decided to achieve basic functions first, meter functions before VNA functions, since this is just software, user interface, PC interoperability and so on. These activities can be so involving, that will distract from basic goals. I did not quantify all possible sources of inaccuracies scientifically, but from experimenting and observing similar designs, I sorted the sources and countermeasures in some order by priority (onion shells on the way to accuracy):

1. Multiple clocking generators behave not completely asynchronously - they are plesiosynchronous. I observed the values abruptly bobbing even in carefully made battery setup. The chart showed 2 clusters of values, reminding the strange attractor. So I decidied to limit the clocking sources and make it a single one. The timebase accuracy is easiest to achieve.

2. Linear power regulators in contrast to switching supplies. That is easy to design, so I went with this path.

3. Mechanical relays vs analog switches. This was obvious decision, even if cost went higher. Also the puzzling about analog switches parasitics can make the design inattractive for beginners. However, I have a design in mind, when those can be negated by 140Db CMRR ability of instrumental amps.

4. Instrumentation amps were called to improve the phase resolution at very low signal levels.

Edit: Eh, the order of priorities is not very clearly explained. ..  I simply attacked every noise and uncertainty source I saw, and then resolved before proving the need scientifically. My goal is highest possible repeatability (matching of consequent measurements in short or medium period of time) and basic accuracy is just second to top priority. That is why I dedicate so much to noise cancellation, when, instead, I could focus on drifts, embedded references, self calibration abilities etc. I found that noise is most distracting thing, so to continue improvements I had to spot and resolve the noises first.

TLDR: Repeatability > Accuracy
« Last Edit: August 10, 2015, 11:38:58 pm by unitedatoms »
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Offline TheAmmoniacal

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #11 on: August 10, 2015, 11:35:24 pm »
What about phase angle and dissipation factor?
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Offline unitedatoms

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #12 on: August 10, 2015, 11:41:05 pm »
What about phase angle and dissipation factor?

Yes.
It measures Immitance parameters: Impedance ( Resistance and Reactance ), Admittance (Conductance and Susceptance ). Capacitance, Inductance, Equivalent Series Resistance (ESR), Q factor, D value, Loss angle and Loss Angle Tangent in range of frequencies 10Hz to 100KHz (with possibility to reach 200KHz, but it is yet to be seen).

Phase angle and dissipation factor are always part of measurement. I had to spell the "Q value, D factor" instead of "Q factor, D value". thank you for asking.
« Last Edit: August 10, 2015, 11:43:57 pm by unitedatoms »
Open Hardware DIY Kit LCR/ESR Impedance meter UA315
 

Offline timofonic

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #13 on: August 11, 2015, 12:17:09 am »
I would like a SMT design. I want to improve my soldering skills and the price reduction could make it a lot more interesting too.
 

Offline unitedatoms

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #14 on: August 11, 2015, 12:29:30 am »
I would like a SMT design. I want to improve my soldering skills and the price reduction could make it a lot more interesting too.

Great to hear this! I did not think that anyone will choose SMT over through hole. The main board has 3 SMD 16 pin chips, so I can leave the soldering to the user completely and stop worrying about solder type mismatch. This can be optional for user to choose with connection to price discount.

I use PbFree Tin Bithmusth Silver solder over (pure ?) tin HASL boards. The solder is (made in Massachusetts) very low temperature one and melts at 138C! It can cause trouble when mixed with lead, that melting temperature can drop too low. It will be great if the choice about environment impact went to users. (Though I have to consider the need to increase the copper from 1 Oz to 2 Oz thickness - so multiple resoldering will not cause too much foil dismembering, and also I have to understand if lead free HASL is acceptable by users, many may prefer lead based or gold plating or something else).

The digital board is TQFP100/0.5mm + TQFP128/0.4mm + 40Pin/0.5mm pitch flat connector. Those are impossible to solder without heat gun or underheat or oven. Plus most people will need a microscope. So I decided to solder the digital board 100% myself.

Another labor/cost reduction idea is to let users drill / cut the enclosure. It is 0.8mm painted steel. Many of builders like to use dremel or have an access to machine shops, it will be great cut for me on labor and good discount for users, if they choose to do so.
« Last Edit: August 11, 2015, 12:58:25 am by unitedatoms »
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Offline timofonic

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #15 on: August 11, 2015, 01:00:39 am »
I would like it the hard way, because of didactic and economical reasons. I'm studying at a vocational school, we need to be proficient at soldering and desoldering, even packages using big pins with heat guns and ovens.

Does the project features a good continuity tester feature too?
 

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #16 on: August 11, 2015, 02:25:01 am »
Continuity tester! What a great use, yes. The instrumentation PGAs are perfect for microohmmetry. I am yet to see the resolution at lower range, but I hope for good resolution / repeatability (ignoring the accuracy of 1% 0.2Ohm resistor - which is an impossible claim of any incomplete datasheet, if you think of typical 50ppm 1% resistor, look only after repeatability).

I saw few mentions of using microohmmeters to find the defects (shorts, tin whiskers ?) location by sliding the probes over copper traces. This would be interesting to see. I am so excited, that you mentioned it, because for most ranges there is no much need to have a high CMRR expensive PGA parts. And I have been mostly worrying about high range with shielding, grounding and parasitics, and forgot about microohms. But for micro ohms it is just a software, and perhaps the little sound speaker - beeper.

Another frontier is supercapacitors and batteries. Those also are in microohm range.
« Last Edit: August 13, 2015, 12:37:11 am by unitedatoms »
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Offline timofonic

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #17 on: August 17, 2015, 06:51:50 pm »
There were some talks about a specific continuity tester here, maybe it could give you some inspiration in terms of features and such...

http://www.eevblog.com/forum/index.php?topic=15435.0
Continuity tester with glitch capture
 

Offline zapta

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #18 on: August 18, 2015, 01:33:25 am »
OP,  you mention a few optimization that reduce the noise at increased cost (latching relays, powering from supercaps, etc). Are you convinced that they are required and justify the cost?  Have you tried without them?  (premature optimization is a common design sin).

Also, if you intend to power it from a 5V USB charger, why not using a standard USB connector?

Kudos for making it open source.
« Last Edit: August 18, 2015, 01:35:15 am by zapta »
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Offline unitedatoms

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #19 on: August 18, 2015, 05:23:28 am »
OP,  you mention a few optimization that reduce the noise at increased cost (latching relays, powering from supercaps, etc). Are you convinced that they are required and justify the cost?  Have you tried without them?  (premature optimization is a common design sin).

Also, if you intend to power it from a 5V USB charger, why not using a standard USB connector?

Kudos for making it open source.

Thank you for asking. Latching relays is byproduct of choosing capacitors based power supply. I chose latching relays (to reduce the consumed power) after choosing capacitors based supply. I tried several ways to power different prototypes: USB power from HUB + LDO as in Analog Devices reference circuit, batteries, AC linear power and AC-CD converter. I did not try to run from supercaps yet, just made a board layout and waiting for boards from Seeedstudio.

I can tell from experience that switching supply is the worst noise wise. The battery based supply gave the best results. I am convinced that supercaps are relatively cheap and reasonable way to build noiseless power supplies, they are not the major cost b.t.w. The major cost comes from precision resistors, relays, instrumentation amplifiers and ADI chip.

The LCR measurement is basically very sensitive I-Q demodulator, similar to synchronous detectors in radio. When one builds sensitive radio receiver, containing in-band transmitter on the same board, which run simultaneously and powered from same power supply, the PSRR becomes a major noise factor. If PSRR is, say 80Db, the microvolt error is caused by 10mV noise on power rail. And if the measured signal is 1mV (in some ranges even less), the error of 1uV is 0.1%.


USB connector: I can not find affordable panel mount USB connector. The requirement is, it has to cover the hole edges completely, and it happened so, that in whole industry all USB connectors are designed for injection mold enclosures. Not for sheet metal panels.  Or may be I was not looking for it well enough.


« Last Edit: August 25, 2015, 01:39:51 pm by unitedatoms »
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Offline timofonic

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #20 on: August 28, 2015, 12:22:07 pm »
Any progress on your project?

Are you considering Sigrok compatibility?

You can put it in GitHub, so we can follow it easily.

Thanks for your project and good luck with it!
« Last Edit: August 28, 2015, 12:28:41 pm by Circuiteromalaguito »
 

Offline unitedatoms

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #21 on: August 28, 2015, 11:09:21 pm »
Any progress on your project?

Are you considering Sigrok compatibility?

You can put it in GitHub, so we can follow it easily.

Thanks for your project and good luck with it!

Project is still in progress. I have made 42 digital boards out of 50. And now making the first analog board. For last 2 days stuck on 555 timer based power supply part. But resolved it OK. The analog boards will have to be changed. Most of the change is around 555 reset pins.

The Sigrok looks interesting. I will not add it to the first version (batch of 50 kits). Too late to add anything. But will consider it for next batch. The major problem with connectivity to anything is nice looking connector for USB Type B. I can not find any panel mount connector for normal price.

Update: Aug 28th. Received few more parts today and was able to run 2 boards together with half of analog board populated:

« Last Edit: August 29, 2015, 09:03:58 am by unitedatoms »
Open Hardware DIY Kit LCR/ESR Impedance meter UA315
 

Offline timofonic

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #22 on: September 20, 2015, 01:10:59 pm »
Any more news? Your project looks really interesting!
 

Offline free_electron

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #23 on: September 20, 2015, 01:26:52 pm »
uses supercomplex A/D  device , processor and lcd diplay with own graphics processor..
power supply ? 555 driven ...  :palm:
Professional Electron Wrangler.
Any comments, or points of view expressed, are my own and not endorsed , induced or compensated by my employer(s).
 

Offline timofonic

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Re: OSHW LCR/ESR Impedance Meter. DIY benchtop kit UA315
« Reply #24 on: September 20, 2015, 02:05:17 pm »
uses supercomplex A/D  device , processor and lcd diplay with own graphics processor..
power supply ? 555 driven ...  :palm:

Please....


Would you like to elaborate more about such topics and what's bad with it?

What would be the best approach?

It would be very nice to know a detailed opinion about it

Thanks in advance;


Best regards.
 


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