Tag Archives: Logic Probe

Audible Logic Probe

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We can use NE556 timer IC to make indication of static of terminal in digital logic audible.  Audible logic probe can be very useful when we have to visually inspect a part while need to check the logic state on other point apart from the part.  Here’s the circuit diagram:… Read more »

Simple Discrete Logic Probe

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This is simple logic probe circuit. Logic probe is used to determine if a point in a circuit has high or low state when the circuit is in operation.  Here is the schematic diagram of the circuit: When the probe is not touching any circuitry, this circuit consumes no current…. Read more »

Audible Logic Probe/Indicator

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Logic indicator circuit / logic probe is used to identify logic level at any point of logic circuitry. The indicator can be visual (using LED, LCD, of 7 Segments) or auditory (using beeper or speaker). This circuit has a audible indicator, with the help of  a loudspeaker to produce indication… Read more »

Darlington Transistor Pair Logic Probe

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Ideally, any testing equipment will not draw any current from the device under test. This ideal condition can be approximated by  designing a testing device with a very high input impedance for negligible loading, and this Darlington logic probe circuit could be one of this. This circuit uses two transistor… Read more »

High/Low Voltage Probe

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Simple voltage probe circuit shown in the schematic diagram below very useful in testing, testing, or troubleshooting discrete  or integrated circuits, especially logic circuitry. This voltage probe circuit gives two indication, “high” or “low”. Here is the schematic diagram of the circuit: When the “high” condition is probed, Q2 and… Read more »