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Topic: ESR meter with Arduino (Read 76 times) previous topic - next topic


:smiley-sleep: ...is there anyone who has successfully measured low ohmic values??, for example 0.1 or 0.01; appropriate values ??to an ESR meter;)


Hi Baravantan,
To answer your last question, yes, I have measured what seem to be good values in the milliOhm range. I have a 100mOhm precision resistor and have measured many capacitors with what appears to be reasonable and repeatable results.
I took a quick look at your code and all appears to be OK with the actual calcESR routine. I didn't look at your PCB layout so I can't say more than that in my proto-board build I used the schematic exactly as in the original post EXCEPT that I used a 10microFarad cap and a 110Ohm resistor in the pulse circuit (47micro and 100 Ohm in the original).
I did notice in testing that the whole thing is very sensitive to the declared supply voltage and the value of this resistor. And I noticed in your code the following...

double Vin_LO = 4700; // milliVolts
uint16_t Rs_LO = 110; // Ohms

Are you actually using a 110 Ohm resistor? And is your supply voltage really only 4,7 V? Unless these (and the Vref voltage) are well defined, the calculation can be very non-linear.
Anyway, hope this helps.


Hi, Totoro, and thanks for your help!
These days I've done some tests, including the correction of the parameters that you have shown me, but without solving the problem.

double vRef = 1.079; // Volts
double Vin_LO = 4980; // milliVolts
uint16_t Rs_LO = 99.8; // Ohms

All values ??measured with a €40 multimeter (what I have)

Considered that your ESR Meter works, surely my problem isn't in the code.
I think there is a lot of work waiting for me...

Thank you again.


May 17, 2013, 05:52 am Last Edit: May 17, 2013, 05:55 am by cepc Reason: 1

Sorry, I am just a breadboard/point-to-point/proto-board type. My main need for an ESR meter is to troubleshoot old audio gear and test equipment.

Hello  Totoro , I am having a hard time wrapping my head around which pins you hooked up to the 7 segment displays, can you possibly draw something quick showing pinouts?   i dont want to use a lcd display,  im going to make a smd version of the board and will post the results after i have a working prototype.

thanks so much!

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May 17, 2013, 06:50 am Last Edit: May 17, 2013, 07:45 am by cepc Reason: 1
ohh crap.    :smiley-red:

i need to take it easy on the drinking.. i think

let me guess:  these are the common anodes (or cathode depending on display.) going to a transistor for each.

#define PIN_DIG_0 10 // least significant digit
#define PIN_DIG_1 11
#define PIN_DIG_2 12
#define PIN_DIG_3 13

these go to their respective pins on display..

#define PIN_SEG_DP 8
#define PIN_SEG_A 3
#define PIN_SEG_B 2
#define PIN_SEG_C 9
#define PIN_SEG_D 6
#define PIN_SEG_E 7
#define PIN_SEG_F 4
#define PIN_SEG_G 5

or do i need to stop drinking???  i think i can keep drinking.  ]:D
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