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Thank you, the filter works nicely! Now I can add one of those ebay OLEDs to the unit and Arduino takes care of removing offset etc. Wonderful project of yours JayDiddy!
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I also made a similar resistance calibrator.During the calibration process, I found a problem.Whether the measured value is accurate?
I tried to adjust the 500 ohm variable resistor, but the effect is not obvious.Is it my installation failure or is the circuit originally like this?
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Has anyone created a PCB for this??
Thanks! -
I also made a similar resistance calibrator.During the calibration process, I found a problem.Whether the measured value is accurate?
I tried to adjust the 500 ohm variable resistor, but the effect is not obvious.Is it my installation failure or is the circuit originally like this?
Hi,
I just measured one my ESR meter adapters.
I first use a zero
standard like this:
With the short in place, I pressed the relative button on the DMM.
I used a resistance 'standard' like this one:
and
I measured the actual values of the resistors with a Keithley 2001 in the 4W mode.
I then use the ESR meter adapter to measure some of the resistors.
There is good agreement with the actual values.
Regards,
Jay_Diddy_B
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Hi group,
Here are few more pictures:
The zero Ohm standard
You use this so you are measuring a very short, very wide, pcb trace.
You use the short like this.
Jay_Diddy_B
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Love the idea & implementation of that simple resistance standard.
Going to make one as all I need is just bunch of resistors, the test point inserts and a piece of single sided blank PCB and sharp cutter.
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This is what I made.I will short the 4 clips (as shown).Is this wrong?
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I adjusted R22 and R6, the effect is not obvious, I don't know why?Need me to get an oscilloscope waveform?
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[ Specified attachment is not available ]More than 100 milliohms
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daisizhou.
With the connections that you have in the picture, press the REL on the Fluke meter.
Now connect a 10 1% resistor to the adapter. Adjust the potentiometer for a reading on the meter of 1.000V (corresponding to 10 ).
The adapter is now adjusted and ready to use.
You need to the zero adjustment in the future. Short the leads and press REL on the Fluke DMM.
You are not just zeroing the leads, but the offset from the opamp in the adapter.
Regards,
Jay_Diddy_B
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Yes, I am also adjusting this way.But I adjusted the R22 potentiometer and the multimeter value did not change much.
I don't know where the fault is?Actual measured values are too large -
daisizhou,
Try this procedure:
1) set R22 in the middle of range. It is a 500 pot so this is about 250
2) Short all the inputs together. Press REL on the DMM to remove the offset.
3) connect a 10 resistor to the test terminals.
4) Measure the voltage on the DMM
5) The DMM should read around 1.00V
The total resistance in the circuit is:
R4 + U2B(on) + R6 + R22 + R7 + R18
470 + 80 + 1.3K + 250 + 100 +100 = 2300
This is the total resistance in the path.
So if you are 5% high, say 1.05V, you need to increase the path by 5% or 115
so change R6 from 1.3K to 1.5K
Regards,
Jay_Diddy_B
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nice i succeeded .
Very good effect.
Is there an upgrade plan for the circuit? Such as measurement accuracy, and so on... -
nice i succeeded .
Very good effect.
Is there an upgrade plan for the circuit? Such as measurement accuracy, and so on...
I have no plans to make any improvements. For the following reasons:
1) This adapter is intended for troubleshooting and repair. A bad capacitor will have an ESR several times larger than a good one.
2) ESR is generally specified by manufacturers as a maximum value. A new capacitor is typically 1/3 or 1/2 of the maximum value.
3) ESR is temperature dependent.
4) The ESR meter adapter, presented here, has a lot of protections against damage from charged capacitors and applied voltage. A typical LCR meter will not have these protections.
If I need better accuracy I use an HP4274A LCR meter.
The DER-5000 is a reasonably priced LCR meter widely available on eBay.
What level of performance do you desire?
Why do you need these accuracy?
Regards,
Jay_Diddy_B -
I am going to measure the internal resistance of a lithium battery, such as the 18650 battery that is now widely used.
In amateur conditions, I often repair these batteries.Such as sweeping robots, remote control aircraft
In practice, these batteries are all connected in series.As long as one section of the link is damaged, the whole system will not work.
I hope to use this tool to identify the batteries that can be used and the damaged batteries.
(Battery internal resistance is generally 30 milliohms) -
Hello, have you measured the internal resistance of the 18650 battery?
I found that measuring the internal resistance of the 18650 battery with this tester is very inaccurate.
I am checking, I don't know where the problem is.
I use a 1 milliohm resistor and a 10 milliohm resistor and a 2.2 milliohm resistor as a standard.
Using these resistance measurements, multiple tests, the effect is very good,The data is accurate
But measuring the 18650 battery is not accurate. -
Hello, have you measured the internal resistance of the 18650 battery?
I found that measuring the internal resistance of the 18650 battery with this tester is very inaccurate.
I am checking, I don't know where the problem is.
I use a 1 milliohm resistor and a 10 milliohm resistor and a 2.2 milliohm resistor as a standard.
Using these resistance measurements, multiple tests, the effect is very good,The data is accurate
But measuring the 18650 battery is not accurate.
Hi,
Battery impedance is different than capacitor ESR. It is frequency dependant. It is explained here:
Link: https://batteryuniversity.com/learn/article/how_to_measure_internal_resistance
Much better than I can explain it.
It includes the comment:
For example, Li-ion in an 18650 cell produces about 36mOhm with a 1,000Hz AC signal and roughly 110mOhm with a DC load. Since both readings are valid, yet far apart, the user must consider the application.
I don't think the ESR adapter described in this thread is directly suitable for the measurement.
Thinking ….
Regards,
Jay_Diddy_B -
Hi,
I am going to show a few quick measurements that I made on a Li-ion cell. This is the cell that I tested:
This a PKCELL 2200mAh ICR18650 cell. It is a few years old. I gave it a quick charge at 4.2V before I did the testing. The battery was probably around 20% depth of discharge (80% full).
HP4328A Milliohmmeter
This an old school meter that use 1kHz sinewave excitation. The meter was set on the 100m scale. This conforms to the 1kHz test method described in the Battery University webpage.
The measured ESR was79mCorrected, see messages below, 69m.
Electronic load and oscilloscope
The battery was connected to an electronic load. A Tektronix current probe was used to monitor the current. This is the green trace.
The battery terminal voltage was measured, ac coupled, cyan trace.
The load was set to go between 0.25A and 1.25A, 1A pk-pk.
1 kHz
The peak to peak voltage is 76mV. A resistance of about 75m
10 Hz
The peak to amplitude increased to 98mV. The indicated ESR = 98m
LTspice Model
A quick LTspice model with similar behavior:
And the modeling results:
This set of test shows that measuring battery ESR different ways, you get different answers.
Regards,
Jay_Diddy_B
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My impression of ESR internal resistance testing of batteries was only for comparative testing anyway to determine the approximate aging effects, of new vs old. Like capacitors (or any component really if you consider it's variable testing conditions) the results if reproducible on single instrument aren't guaranteed to line up between instruments. But if the measurement is reproducible on the one instrument and varies between different DUTs enough to characterize good vs bad or somewhere in the middle, as far as I'm concerned job done. Otherwise if you want like for like testing then use the same testing method that defined the specification.
Btw Jay_Diddy_B that HP meter looks to be reading 69 milliohms not 79. -
Quote
Btw Jay_Diddy_B that HP meter looks to be reading 69 milliohms not 79.
+1 -
Quote
But if the measurement is reproducible on the one instrument and varies between different DUTs enough to characterize good vs bad or somewhere in the middle, as far as I'm concerned job done.
+1 -
Hi,
It is a correct observation that the ESR of cells can only be compared if the test method is the same. If the measurement is being used for selecting or matching cells stick to one method.
The popular methods are:
1) a dc measurement. You step the load current between two values and measure the change in terminal voltage with a DMM. From change in voltage divided by the change in current you can arrive at the ESR.
This method is probably the best method because it is similar to the intended application.
2) You can measure the ESR using 1 kHz sinewave, with an instrument like HP 4328A. You can use other 4-wire LCR meters if use blocking capacitors.
Keysight suggests:
3) Battery Chemists will use electrochemical impedance spectroscopy and measure the real and imaginary parts of the battery impedance. This gives them insight into what is happening inside the cell.
The impedance changes with:- temperature
state of charge
operating point
aging
They would use a frequency response analyzer, FRA, to do these measurements.
4) if you have an electronic load like the one I describe in this thread:
link: https://www.eevblog.com/forum/projects/dynamic-electronic-load-project/
and oscilloscope or even a DMM you can compare cells. You can do static dc tests or AC 1 kHz comparison tests.
Regards,
Jay_Diddy_B
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Damit ! the 74hc4053 model in kicad is wrong ! pins 14 and 15 are inverted.
my pcb just arrived from china and is wrong too ...
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Damit ! the 74hc4053 model in kicad is wrong ! pins 14 and 15 are inverted.
my pcb just arrived from china and is wrong too ...
That is unfortunate ..
here is the bad code:Code: [Select]1 EESchema-LIBRARY Version 2.3
2 #encoding utf-8
3 #
4 # 74HC4053
5 #
6 DEF 74HC4053 U 0 40 Y Y 1 F N
7 F0 "U" -50 750 60 H V C CNN
8 F1 "74HC4053" -50 -550 60 H V C CNN
9 F2 "" 0 0 60 H V C CNN
10 F3 "" 0 0 60 H V C CNN
11 DRAW
12 S -350 600 450 -300 0 1 0 N
13 X 2Y1 1 650 150 200 L 50 50 1 1 B
14 X 2Y0 2 650 250 200 L 50 50 1 1 B
15 X 3Y1 3 650 -150 200 L 50 50 1 1 B
16 X 3Z 4 650 -250 200 L 50 50 1 1 B
17 X 3Y0 5 650 -50 200 L 50 50 1 1 B
18 X E# 6 -550 -250 200 R 50 50 1 1 I
19 X VEE 7 -550 100 200 R 50 50 1 1 W
20 X GND 8 -550 0 200 R 50 50 1 1 W
21 X S3 9 -550 350 200 R 50 50 1 1 I
22 X S2 10 -550 450 200 R 50 50 1 1 I
23 X S1 11 -550 550 200 R 50 50 1 1 I
24 X 1Y0 12 650 550 200 L 50 50 1 1 B
25 X 1Y1 13 650 450 200 L 50 50 1 1 B
26 X 1Z 14 650 350 200 L 50 50 1 1 B [color=red]… this wrong J_D_B
[/color]27 X 2Z 15 650 50 200 L 50 50 1 1 B [color=red]… this wrong J_D_B
[/color]28 X 16 VCC -550 200 200 R 50 50 1 1 W
29 ENDDRAW
30 ENDDEF
31 #
32 #End Library
This may have been fixed, see this link:
https://github.com/alexisvl/kicad-schlib/commit/d514c0f8439e177c63e06c8c35dd6111535f07aa
Hopefully you can fix the board with a jumper.
Regards,
Jay_Diddy_B -
yeah I fixed it with some cutting and jumper. but this brand new pcb is already a mess !
this was also to warn other users that may use kicad to make their own esr meter.