Elektronica Stynus
 

ESR-Meter

Some time ago I came across this design of an ESR meter. I then decided to build it, but for the display I wanted to use a pic + lcd.

My circuit:
schema
(Clickable)

 

Pictures:
Frontplaat ESR-Meter
ESR-Meter
ESR-Meter

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Update 22/07/08

I made a mistake in my circuit. The non inverting inputs off the opamp should be connected to 2,5V instead of the ground. I could make a new pcb, but I decided to make it myself easy and made a special ic socket with a voltage divider build in.

bugfix

bugfix

bugfix

The new circuit diagram:

schema

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Update 24/02/09

I got the code working. Apparently there is a bug in picbasic that gives problem with the AD on a 16F690. Therefore I made my own code to get the analog value.

 

The code:

  Device 16F690
Config INTRC_OSC_NOCLKOUT, WDT_OFF, PWRTE_OFF, MCLRE_OFF
XTAL = 8
OSCCON = %01110111

Dim spanning As Word
Dim
esr As Float

Declare
LCD_DTPIN PORTC.4
Declare LCD_ENPIN PORTC.3
Declare LCD_RSPIN PORTB.6
Declare LCD_LINES 2

TRISA.2 = 1
ADCON0 = %10000001
ANSEL = %00000100
ANSELH = %00000000

ADIN_RES = 10
ADIN_TAD = FRC
ADIN_STIME = 500

Symbol lcdTijd = 600
Clear
Cls
Print At
1, 1, "ElektronicaStynu"
Print At 2, 1, " ESR-Meter V1.2 "
DelayMS lcdTijd
Print At 1, 1, "lektronicaStynus"
DelayMS lcdTijd
Print At 1, 1, "ektronicaStynus."
DelayMS lcdTijd
Print At 1, 1, "ktronicaStynus.b"
DelayMS lcdTijd
Print At 1, 1, "tronicaStynus.be"
DelayMS lcdTijd

Cls
Print At
1, 1, " ESR-Meter V1.2 "
Print At 2, 1, " ESR = , "
Print At 2, 16, $FE,$40,$00,$0E,$11,$11,$11,$0A,$1B,$00



While 1 = 1
GoSub AD_in
spanning = spanning - 480
esr = spanning / 19
If esr > 27 Then
Print At
2, 9, "Open "
Else
Print At
2, 9, DEC2 esr , " "
EndIf
DelayMS
550


Wend
AD_in:
ADCON0 = %10001001
DelayMS 510
ADCON0.1 = 1
While ADCON0.1 = 1 : Wend
spanning = 0
spanning.HighByte = ADRESH
spanning.LowByte = ADRESL


Return
End

The hex file

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Update 26/03/2011

There was another adaptation on the pcb that was not in the circuit diagram above.

The LCD has to be connected differently. I don't know why anymore, but here is the new circuit diagram:


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Files

I received Eagle files from Predrag Mihajlovic for this esr meter. They can be downloaded here: Link.
Hello,
I did 2 versions. First is one based on your schematics, except that I've changed those smd capacitors for standard through hole ones. Second one is somewhat modified. I've excluded transformer and put in standard dc jack. Also, pic and display header are located so far away from other stuff so that there is enough place for display to be on the pcb. Also, you'll see that, on both versions I've also put pads for 27 and 22mm capacitors (4.7uF). Check it out and feel free to make any modifications you think are necessary. You can put it on your website if you like, maybe someone will find it useful :)
Peca.

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