Logic Probe With Sound


Posted on Feb 7, 2014

This logic probe can be selected to operate on TTL or CMOS logic levels, depending on switch S1. A string of resistors associated with switch S1 sets the threshold levels for a window comparator comprising IC1a and IC1b. Depending on whether the level applied to the probe is high or low, the window comparator turns on LED1 (high) or LED2 (low). Th


Logic Probe With Sound
Click here to download the full size of the above Circuit.

e 1. 2M and 680k resistors set the probe signal to a midrange value when the probe is open-circuit, thereby preventing either LED from being lit. If a pulse signal is present, the output of IC1a will toggle the clock input of flipflop IC2a. This drives LED3 which either lights for each pulse or continuously, depending on the setting of switch S2. Finally, the outputs of IC1a & IC1b are connected by diodes D5 & D6 to the base of transistor Q1 which is connected to the Reset input of flipflop IC2b. This has a piezo sounder (not buzzer) connected between its Q and Q-bar outputs so that it produces a sound which echoes the input pulse signal.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Casio cable for PC
    Audio Light Modulator circuit
    DC 2 speed Motor Controller
    Wireless-telephone-eavesdropper
    439.25Mhz Atv Downconverter Circuit
    Rockwell Jupiter GPS module
    Clap-Sensitive Relay with ON/OFF Feature
    Regulated Positive Voltage Booster
    asymmetric timer
    Triac Testing Circuit PCB
    Digital voltmeter using ICL7107



    Top