Find the Fault
Audible short-circuit finder
Published in issue 355, June 2006
Even the most experienced electronics engineer will undoubtedly come across these: short-circuits in places where they don’t belong. And they naturally occur at times when they’re least welcome. For those who are tired of scanning around a PCB with a magnifying glass, we present here a handy circuit that makes searching for short-circuits on homemade PCBs or already assembled boards a piece of cake.
Resistors
R1,R2 = 220k
R3 = 470
R4,R5,R9 = 20k0
R6,R8,R10 = 1k00
R7 = 17k4
R11,R12 = 100k
R13 = 1M
R14,R16 = 1k2
R15 = 150
R17,R18 = 27k
R19 = 12k
R20 = 68
P1 = 5k linear law mono potentiometer, small model
P2,P3 = 5k preset
Capacitors
C1 = 100pF
C2,C3 = 1nF8 MKT
C4,C5 = 2nF2 MKT
C6,C7 = 22pF
C8,C10 = 470nF
C9,C11 = 1nF MKT
C12 = 1µF MKT, lead pitch 5 or 7.5mm
C13,C14,C17,C18 = 100nF ceramic
C15,C16 = 100µF 10V radial
Inductors
L1 = 35 mH, 100 turns 0.1 mm ECW on Ferroxcube core TL10/6/4-3E5 (Farnell # 3056960) or 92 turns 0.1 mm ECW on Epcos core B64290-L38-X38 (Schuricht # 331648)
L2 = 330µH
Semiconductors
D1,D2 = LED, low-current
D3,D4 = BAT85
IC1 = TS924IN (ST), rail-to-rail I/O (Schuricht # 648226)
IC2 = 74HC132
IC3 = 74HC4040
Miscellaneous
J1 = 16-way pinheader, 1 jumper
BZ1 = AC buzzer
BT1,BT2 = 1.5-V battery with holder
Double-pole switch (power on/off)
PCB, ref. 050313-1 from The PCBShop
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Click below to download a PDF copy of this article from Elektor magazine. Please note. In view of the complexity of international markets, Elektor cannot guarantee the availability of components for this project.
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