TASC Electronics and Advanced Technologies Level 3 flashcards

43 cards. Read the term and the definition here. The deck at the top of this page is optional.

Ohm's law

Voltage equals current times resistance (V = I × R). It relates the three fundamental electrical quantities in a resistive circuit and is the basis for most circuit analysis.

Kirchhoff's voltage law

The algebraic sum of voltages around any closed loop in a circuit equals zero. It reflects conservation of energy and is used in mesh analysis.

Thevenin equivalent

Any linear two-terminal network can be replaced by a single voltage source V_th in series with a resistance R_th. V_th is the open-circuit voltage and R_th is the resistance seen with sources deactivated.

Inverting amplifier gain

For an ideal op-amp with input resistor R_in and feedback resistor R_f, the closed-loop gain is −R_f/R_in. The negative sign indicates a 180° phase inversion.

Nyquist sampling theorem

A signal must be sampled at more than twice its highest frequency component to be reconstructed without aliasing. The minimum rate is called the Nyquist rate.

De Morgan's theorem

The complement of a product equals the sum of the complements, and the complement of a sum equals the product of the complements. Used to simplify logic expressions.

Harvard architecture

A processor design with separate memory buses for program instructions and data. It allows simultaneous instruction fetch and data access, improving throughput in embedded systems.

Watchdog timer

A hardware timer that resets the microcontroller if firmware fails to refresh it within a set period. It recovers the system from software hangs and infinite loops.

Pulse-width modulation

A switching technique that varies the duty cycle of a square wave to control average power delivered to a load. Average voltage equals duty cycle times supply voltage.

Wheatstone bridge

A four-arm resistive bridge that produces zero output when R1/R2 = R3/R4. Small changes in one arm unbalance the bridge and produce a measurable voltage.

4–20 mA current loop

An analog signaling standard where 4 mA represents the minimum value and 20 mA the maximum. The live zero at 4 mA allows detection of open circuits.

LVDT

A linear variable differential transformer that measures displacement. A movable core changes coupling between primary and secondary coils, producing an AC output proportional to position.

Buck converter

A switching DC-DC converter that steps voltage down. In continuous conduction mode, output voltage equals duty cycle times input voltage.

Boost converter

A switching DC-DC converter that steps voltage up. In continuous conduction mode, output voltage equals input voltage divided by one minus the duty cycle.

Power factor

The ratio of real power to apparent power in an AC circuit, equal to the cosine of the phase angle between voltage and current for sinusoidal waveforms.

Shannon capacity

The maximum error-free data rate of a channel equals bandwidth times the base-2 logarithm of one plus the signal-to-noise ratio, in bits per second.

OSI model

A seven-layer reference model for network communication: Physical, Data Link, Network, Transport, Session, Presentation, and Application. Each layer provides services to the layer above.

TCP versus UDP

TCP is connection-oriented and reliable, using acknowledgments and retransmission. UDP is connectionless and best-effort, favoring low latency over guaranteed delivery.

PID controller

A controller whose output combines proportional, integral, and derivative terms of the error signal. Integral action removes steady-state error; derivative action reduces overshoot.

Damping ratio

A dimensionless parameter describing how oscillations decay in a second-order system. Values below one are underdamped, equal to one critically damped, and above one overdamped.

PLC scan cycle

The repeating sequence a programmable logic controller executes: read inputs, solve the logic program, update outputs. Scan time affects responsiveness to fast events.

True-RMS meter

A multimeter that computes the root-mean-square value of an arbitrary waveform, not just a sine wave. Required for accurate readings on distorted or non-sinusoidal signals.

Oscilloscope bandwidth

The frequency at which a displayed sine wave falls to 70.7% of its true amplitude. A rule of thumb is to choose bandwidth at least three to five times the signal frequency.

Four-wire measurement

A technique using separate force and sense leads to eliminate lead and contact resistance. Used for accurate low-resistance measurements such as shunts and trace resistance.

ESD wrist strap

A conductive strap worn on the wrist and connected to ground through a high-value resistor. It safely bleeds static charge from the technician without shock risk.

Lockout/tagout

A safety procedure that isolates hazardous energy sources and applies locks and tags before servicing. It prevents accidental energization and protects maintenance personnel.

Class C fire

A fire involving energized electrical equipment. Non-conductive extinguishing agents such as carbon dioxide or dry chemical are used; water is avoided until power is removed.

Superposition theorem

In a linear circuit with multiple independent sources, the total response equals the sum of responses from each source acting alone with the others deactivated.

RC time constant

The product of resistance and capacitance, denoted τ. In one time constant, a capacitor charges to about 63% of the applied voltage; in five, to about 99%.

Common-mode rejection ratio

The ratio of differential gain to common-mode gain, usually expressed in decibels. Higher CMRR means better rejection of noise present on both inputs.

Setup and hold time

Setup time is how long data must be stable before a clock edge; hold time is how long it must remain stable after. Violations cause metastability in flip-flops.

DMA controller

A peripheral that transfers data between memory and peripherals without CPU involvement. It improves throughput and frees the processor for other tasks.

Brown-out detector

A circuit that resets the microcontroller when the supply voltage drops below a safe threshold. It prevents erratic operation and memory corruption during undervoltage.

Hall-effect sensor

A device that produces a voltage proportional to the magnetic field passing through it. Used for position, speed, and non-contact current sensing.

Incremental encoder

A sensor that outputs pulses as a shaft rotates, giving relative position and speed. Quadrature outputs allow direction detection and resolution multiplication.

Linear regulator

A voltage regulator that dissipates excess power as heat. Efficiency equals output voltage divided by input voltage; it is simple and low-noise but inefficient.

Freewheeling diode

A diode placed across an inductive load to provide a path for current when the switch opens. It prevents damaging voltage spikes and protects the switching device.

ARP

Address Resolution Protocol maps a known IP address to a hardware MAC address on a local network. The result is cached to reduce broadcast traffic.

VSWR

Voltage standing wave ratio measures impedance mismatch on a transmission line. A value of 1:1 indicates a perfect match; higher values indicate reflected power.

Bode plot

A pair of graphs showing magnitude and phase of a system's frequency response versus frequency. Gain and phase margins read from the plot indicate relative stability.

Cascade control

A control strategy with an inner fast loop and an outer slow loop. The inner loop rejects fast disturbances before they affect the primary process variable.

Arc flash boundary

The distance from energized equipment at which incident energy equals the threshold for second-degree burns. It defines required PPE and approach limits for workers.

GFCI

A ground fault circuit interrupter that trips when current leaks to ground, typically at 5–30 mA. It protects personnel from electric shock in wet or outdoor locations.