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MCU88

Programmable Continuity Tester to Build

Easy DIY Continuity Tester With PCB & Schematic.

  1. MCU88
    [​IMG]

    :: FEATURES ::
    • Will not see diodes and other semiconductors as shorts ...
    • Programmable thresholds of resistance to measure using multi-turn trimmer
    • Responds to continuity of a few ohms or kilo ohms denoted by setting of trimmer
    • Audible indication via buzzer and visual by virtue of an LED
    • Low Cost & Easy-to-Build
    • Voltage clamping protection from accidental measurement of voltage
    • Power switch and low power consumption

    [​IMG]
    :: PCB :: (See attached for PDF @100% size to print from laser printer)
    [​IMG]

    :: PCB Overlay Parts Placement ::
    [​IMG]

    :: Parts List ::

    Semiconductors
    IC1 LM393
    IC2 LM78L05
    D1-D2 1N4007
    D3 7V5 Zener
    Q1-Q2 BC547
    Q3 BC557

    Resistors
    2 x 10K
    1 x 100R
    1 x 470R
    1 x 220R
    1 x 2K2

    Capacitors
    1 x 10uF
    1 x 100nF

    Miscellaneous
    8-Pin IC Socket
    SW1 Slide Switch SPDT PC-Mount
    VR1 50K 25-Turn
    Red LED 5mm
    5 Volt PC-Mount Buzzer (Internal Driver Circuit)
    Black Alligator Clip (32mm)
    Red Alligator Clip (32mm)
    9 Volt Batery Snap Connector
    250mm Length of 26AWG Red Hookup Wire
    250mm Length of 26AWG Black Hookup Wire

    Attached Files: