- AC line: Alternating- current power distribution
line. Typically 110V-125V at 60Hz in the United States.
- Alternating current: An electrical current (produced by a voltage)
that periodically changes in magnitude and direction.
- Ampere: The unit of measurement for electrical cur rent in coulombs
(6.25 x 10^8 electrons) per second. There is one ampere of current in
a circuit that has one ohm resistance when one volt is applied to the
circuit. See Ohm's law.
- Amplifier: An electrical circuit designed to increase the current,
voltage or power of an applied signal.
- Capacitor: A device made up of two metallic plates separated by a dielectric
(insulating material). Used to store electrical energy in the electrostatic
field between the plates. It produces an impedance to an ac current,
and opposes changes to the voltage across it.
- Circuit: A complete path that allows electrical cur rent from one terminal
of a voltage source to the other terminal.
- Closed loop: When used in reference to power sup plies, the completed
circuit of the control loop wherein a portion of the output is fedback
to the input to accomplish the control of the output.
- Control loop: The circuit consisting of control de vice, power-supply
output, sampling circuit, feed back signal, error amplifier, and control
voltage. See regulator action discussion in SECTION
3.
- Conversion efficiency: The percentage of input power that a power supply
converts to useful energy at its output.
- Current (I): The flow of charge
(electrons) measured in amperes. See ampere.
- Direct Current (dc): Current in which the charge (electrons) flows
in only one direction.
- Electromagnetic interference (EMI): Disruption of the proper operation
of a radio receiver or other electronic circuit caused by electromagnetic
radiation (noise) from another circuit. This interfering noise may be
transmitted through the air or conducted as power-supply noise.
- Farad (F): The basic unit of capacitance. A capacitor has a value of
one farad when it can store one coulomb of charge with one volt across
it.
- Feedback: An electrical signal from a later processing stage in a regulated
power supply that gives an earlier stage the information it needs to
properly do its task, e.g. the sampling circuit provides a feedback voltage
to the error amplifier.
- Filter: A circuit element or group of components which passes signals
of certain frequencies while blocking signals of other frequencies.
- Frequency: The number of complete cycles of a periodic waveform during
one second, expressed as hertz.
- Ground: Refers to a point of (usually) zero voltage, and can pertain
to a power circuit or a signal circuit.
- Hertz: A unit of frequency equal to one cycle per second, named after
German physicist H.R. Hertz.
- Impedance (Z): The opposition (measured in ohms) of circuit elements
to alternating current. The impedance includes both resistance and reactance.
- Inductance (L): The capability of a coil to store energy in a magnetic
field surrounding it. It produces an impedance to an ac current, and
opposes changes in current through it.
- LC filter: Filter composed of both capacitors (usually paralleled with
the load) and inductors (in series with the load).
- Line voltage: See AC line.
- Load /line regulation: The maximum output-voltage variation allowed
by a regulated power supply in response to load-current or input (line)
variations.
- Ohm (Ω): A unit of electrical resistance, reactance or impedance.
- Ohm's law: A basic law of electric circuits. It states that the current
I in amperes in a circuit is equal to the voltage E in volts divided
by the resistance Rin ohms; thus, I = E/R.
- On time: The portion of the switching waveform during which the control-switching
device conducts.
- Off time: The portion of the switching waveform during which the control-switching
device is not conducting.
- Peak: The maximum amplitude of a voltage or current. For a sine-wave
ac, V_RMS = 1.414Vp.
- Peak-to-Peak: The magnitude of the difference be tween the maximum
positive and negative peaks of a voltage or current.
- Period: For electrical circuits, the length of time required for one
cycle of a periodic wave.
- Phase: The angular or time displacement between the voltage and current
in an ac circuit.
- Polarity: In circuits, the description of whether a voltage is positive
or negative with respect to some reference point.
- Potentiometer: A variable resistance with a wiper mounted on a rotating
shaft.
- Power (P): The rate at which energy is used (voltage times current.)
Reactance: The opposition that a pure inductance or pure capacitance
provides to a current in an ac circuit.
- RMS: An acronym for root mean square. The RMS value of an alternating
current produces the same heating effect in a circuit as the same value
of direct current. For a sine-wave, V_rms = 0.707 V_peak.
- Sine Wave: A waveform of an line alternating current or voltage. Its
instantaneous magnitude is proportional to the sine of the angle of rotation
of the coil generating the voltage.
- Voltage or Volt (V): The unit of electromotive force that causes current
when included in a closed circuit. One volt causes a current of one ampere
through a resistance of one ohm. See Ohm's law.
- Watt (W): A unit of electrical power. It is the use of one joule of
energy per second. One volt times one ampere equals one watt. See Power.
Building Power Supplies (Article Index)
AMAZON
multi-meters discounts
AMAZON oscilloscope
discounts
Also see:
Transistor Circuits (1964)
|