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Capacitor ESR Tester

the good, the bad and the leaky…

Capacitor ESR Tester
How about an in-circuit capacitor tester to take the strain out of tracking down faulty capacitors? No need to solder out any capacitor, simply check it in-circuit, from thousands of microFarads down to a hundred nanoFarads. In most cases, parallel coils or low value resistors are no problem. Even shorted caps may be revealed in-circuit and polarity is irrelevant for the tester. High ESR? Replace!The most significant property of a capacitor is its capacitance but besides that there’s another important factor, namely the so called ESR, or Equivalent Series Resistance. An ideal capacitor is a purely reactive component with a 90-degree phase angle between current and voltage. In the real world, however, a capacitor needs to be modelled as an ideal capacitor in series with a resistor representing the losses introduced by the component.
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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor Members can exclusively download these files for free as part of their Membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service. Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

R1,R13,R14,R17,R18,R19,R31 = 10kOhm
R2 = 4kOhm 7
R3 = 1kOhm 8
R4,R24,R28 = 22kOhm
R5 = 33kOhm
R6,R7,R8 = 2kOhm 2
R9-R12 = 56Ohm
R15,R16,R20,R22,R29 = 1MOhm
R21 = 47Ohm
R23,R25,R27,R30 = 100kOhm
R26 = 1kOhm
P1,P4 = 5kOhm multiturn preset, vertical mounting, side adjust (Bourns 3266X, Farnell #347-747)
P2 = 100kOhm multiturn preset, vertical mounting, side adjust (Bourns 3266X, Farnell #347-784)
P5 = 1kOhm multiturn preset, vertical mounting, side adjust (Bourns 3266X, Farnell #347-723)
P3 = 1kOhm preset, horizontal mounting
C1 = 180pF
C2,C9-C13,C16,C18 = 100nF
C3,C4,C5 = 10µ F 10V radial
C6 = 100µ F 16V radial
C7 = 220nF
C8 = 10nF
C15 = 1nF
C17 = 220nF
D1-D4 = 1N4002
IC1 = 4093
IC2 = 74ACT74 PC
IC3 = 74VHC4066
IC4 = LF412-CN
IC5 = LM2931-5,0
IC6 = 4070
IC7 = ICL7660
IC8 = LM358-N
IC9 = ICL7106-CP
LCD1 = 3.5 Digit LCD with LO-BATT indicator, e.g., Varitronix VI-302 DPRC (Farnell #478-660)
S1 = pushbutton, 1 make contact
Battery holder
On/off switch
2 miniature probes, e.g., Hirschmann PRUF1 (Farnell #523-483)
Length of 2-core screened cable
ABS enclosure with LCD window and battery compartment, e.g. Multicomp type BC4, (Farnell # 645-758)
40-pin IC socket cut in half (see text)
PCB, order code 012022-1
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