Engineering Dictionary of Electronic Terms
"A" "B" "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
"N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"

"R" to "Rad", "Rai" to "Rea", "Rec" to "Relat",
"Relay" to "Resol", "Reson" to "Rh", "Ri" to "Rm", "Ro" to "Rz"

Ribbon Cable. Any cable constructed as a ribbon or flat cable with parallel elements [wire]. Insulated parallel wires attached together by means of adhesive with a plastic covering. Ribbon cable may use twisted or un-twisted wire pairs. Ribbon Cable may also be twisted on a per pair basis, but normally the twisted pairs go to parallel wires about every foot or so, so that even a twisted-pair Ribbon Cable can be used with an Insulation Displacement Connector [Definition of IDC]. Also refer to Companies making Ribbon Cable.

Right Angle Connector. Any style of connector that makes a 90 degree turn. The SMA connector is just one of many possible examples. Right Angle Connectors may be cable to cable board to cable or board to board.
SMA Definition
Manufacturers of Connectors

SMA Right Angle Connector per mil-prf-55339-53
Right Angle SMA

Right Hand Rule. Indicates the relationship that exists between the direction of the current in a conductor and the direction of the magnetic field surrounding the conductor. The fingers show the direction of the magnetic lines of force and the thumb indicates the direction of current. See the diagram to the right for more information.

Rigid Coaxial Line. A coaxial line consisting of a central insulated wire (inner conductor) mounted inside of a tubular outer conductor.

Rigidity. The tendency of the spin axis of a gyro wheel to remain in a fixed direction in space if no force is applied to it.

Ring Counter. A shift register which has its output connected to its input, so that the output of the last stage feeds the input of the first stage.

Ringing. RF oscillations caused by shock excitation of a resonant circuit or cavity. A damped oscillation embedded on an output signal as a result of an abrupt change in the input signal.

Ripple. The voltage from a power supply Harmonically-related to the input voltage frequency.

Ripple Counter. A counter with the different stages connected in series. So that as one stage, or flip flop, changes it effects the next flip flop in line which then effects the next, so that a change in the final stage needs to ripple through all the preceding stages first.

Ripple Factor. The ratio of effective value of the alternating components of the rectified voltage or current to the average value; rf = Irms/Idc.

Ripple Filter. A Low-Pass filter designed to suppress the ripple voltage frequency but pass DC.

Ripple Frequency. The frequency of the ripple current. In a full-wave rectifier it is twice the input-line frequency. [Full-wave Rectifier Circuit and waveform]

Ripple Rejection. The ratio of rms input ripple voltage to the rms output ripple voltage.

Ripple Voltage. The alternating component of a unidirectional voltage. (This component is small compared to the direct component.) The AC voltage riding on top of a DC voltage. In a dc voltage, the alternating component that is residually retained from rectification of ac power, or from generation and commutation.

Ripple Waveform
Ripple Voltage Waveform

Riser. A riser is a power line pole that connects an overhead system to an underground system. A riser has a conduit from the ground up the pole where heads are used to connect to the overhead lines.

Rise Time. The time required for the leading edge of a pulse to change from 10 to 90 percent. Read more on Pulse Characteristics. In the approximation of a step function, the time required for a signal to change from a specified low value to a specified high value.

RLC Circuit. An electrical circuit that has the properties of resistance, inductance, and capacitance.

RL Differentiator. An RL circuit in which the output is taken from the inductor.

RL Integrator. An RL circuit in which the output is taken from the resistor.

RMS. Abbreviation of root mean square. The Direct Current [DC] equivalent of an Alternating Current [AC] waveform. The voltage equivalent of an AC waveform.

Square Wave: IRMS = (Tp/T)1/2
Sawtooth: IRMS = Ipk / (3)1/2
Clipped Sawtooth: IRMS = Ipk * (Tp/3T)1/2 [even pulses missing]
Half Sine Wave: IRMS = Ipk * (Tp/2T)1/2 [even pulses missing]
Full Sine Wave Rectified: IRMS = Ipk / (2)1/2
Alternating Sine Wave: IRMS = Ipk / (2)1/2
Square Wave: IRMS = Ipk
Triangle Wave: IRMS = Ipk * (Tp/3T)1/2

Tp = Pulse Width, T = Period, Ipk = Peak Current value

PC motherboard

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