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Acronym-a-Mania [Newbie Bible]

Here's a start of a list of ACRONYMS that you see everywhere here ... that are kind of daunting unless we know what they mean. I invite EVERYONE to add more. Every once in awhile, I'll consolidate the list.


A - amp
ADC - analog (waveform) to digital (bits) conversion
BJT - bipolar junction transistor. AKA "transistor". See NPN, PNP
BNC - "Banana Naval Connector" - a kind of high-reliability, low-insertion loss, positive-lock coaxial connector
C - capacitor
C core - Core that is circular, and CUT into a pair of 'C's'
CCS - constant current source
CMRR - (see PSRR) common mode rejection ratio - ability of circuit to block ripple/noise that's in common to both input pins
COAX - coaxial wire, with single (usually) conductor in center, and a braided or other wrap-around shield on outside.
COP - cost of production
CVS - constant voltage source
Class A - a SE output amplifier
Class AB - a PP output amplifier with substantial crossover overlap
Class B - a PP output amplifier, with near-zero crossover overlap
Class D - a "digital" amplifier, using PWM and NFB to control output
DA - digital audio
DAC - digital (bits) to analog (waveform) conversion
DFT - discrete Fourier tranform - similar to FFT, but much longer to execute. Easy to program though!
DI - direct "inject" - a kind of preamplifier used in sound systems, that is physically positioned near the musicians.
Direct Box - a DI
EC - electrolytic capacitor - polarized and often somewhat non-linear in action
EI - shape of the plates in a common type of transformer. One side shaped like E, other side I.
ENC - enclosure
FET - field effect transitor - one of the earliest type, relying on a gate field to modulate current flow. Like a tube/valve
FF - far field - the frequency sonics at many-meters from speakers.
FFT - fast Fourier transform - an algorith that converts N data points into N/2 frequency/phase points.
FO - fiber optic
FWB - full-wave bridge - rectifier circuit that captures both positive, and inverted - negative transformer pulses.
GND - ground
GP - ground plane
Hfe - BJT current 'multiplication'. If 1 ma into base gives 100 ma through collector, Hfe = 100/1 = 100
Hz: Hz = Hertz = full sinusoidal (or "back to beginning" for non-sinusoidal waveforms) repetions per second
Hz: GHz = giga- = 1,000,000,000x Hz ... computers, microwaves, cell phones, WiFi
Hz: MHz = mega- = 1,000,000x Hz ... broadcast radio ranges
Hz: THz = tera- = 1,000,000,000,000x Hz ... non-invasive security checkpoint imaging equipment
Hz: kHz = kilo- = 1000x Hz ... middle of audio band
IMD - intermodulation distortion - complex distortion common to many PP amplifier designs
J - usually a JFET
JFET - junction FET - having a gate in contact with the underlying conductor channel material. Sturdy, very triode like in practical applications
L - inductor
LC - inductor-capacitor combo, which in different configurations can act as a narrowband pass filter, or a cut (notch) filter, etc.
LFB - local feedback - techniques reducing gain of individual stages, increasing their linearity in process
LTP - long tail pair (a differential-input pair of BJTs/FETs/tubes using a CCS to create a complimentary output)
M - mega, often "meg ohm"
MOSFET - metal oxide FET - where the gate is separated by an oxide dielectric from the conduction channel. Sensitive to static, but can be made in very high power configurations
NF - near field - close to speaker, close to microphone
NFB - negative feedback - used to (downwardly) adjust overall gain to increase linearity and theoretically counteract cross-over (and all other) distortion
NOOB - "newbie", in a not so nice handle
NOS - new, but "old stock", not usually manufactured any more.
NPN - one of the two "polarities" found in BJT transistors. ("negative-positive-negative" doping)
OL - ohms law - E = I R where E = voltage, I = current flow, and R = resistance
OPAMP - operational amplifier - the workhorse of post 1970 'conventional' analog design
PNP - one of the two "polarities" found in BJT transistors. ("positive-negative-positive" doping)
POT - potentiometer, variable resistor, "volume" control (etc.)
PP - push-pull, utilizing 2 active devices, one for the positive signal excursions, the other for the negative.
PS - power supply
PSRR - (see CMRR) power supply ripple rejection - ability of circuit to block power ripple from propagating to the output
PWM - pulse width modulation - rapidly switching ON then OFF a power supply, the "width" of which when integrated through Ls and Cs becomes a smooth waveform
Q - usually a BJT
QIJ - quarter-inch jack - the recepticle for QIP
QIP - quarter-inch plug - common for electric guitars, "professional" audio equipment
R - resistor
R = resistance, often "ohms" for historically questionable reasons
R core - radial, wound core, not split. Very challenging to make transformers using. High quality.
RC - resistor-capacitor combo, like LC, but only "one pole" - having a much more relaxed rate of out-of-band frequency quenching (6 dB/octave)
S = siemens = amps per volt (see gm)
SCR - silicon controlled rectifier (NPNP configuration) Normally off semiconductor, triggered into conduction easily by a much smaller gate connection.
SE - single ended - an amplification section having but one active device (triode, pentode, FET, BJT). Runs hot, but reputedly sounds sweet!
SET - single ended triode - an SE with a valve/tube as the amplifying element
Scope - oscilloscope - device for capturing and visualizing waveforms in real-time.
V - volt
VOM - volt-ohm multimeter - used to be complicated, now digital and inexpensive.
VTVM - vacuum-tube volt-meter (even when FETs were used!) very sensitive VOM
WW - wire-wound - applied to resistors, using fine wire to create resistance. Often inductive.
XLR - 3 pin connector used in high quality microphone cables (and other uses)
cascode - a two-active-device amplification circuit that gives the amplifying valve a constant voltage at its plate/collector/drain pin. Counteracts the frequency sapping of Miller capacitance
dB - deciBels - which without other specification refer to (20 log( ratio )). So, 2x = 20 * log( 2 ) = 20 * 0.301 = 6 dB
dBm - decibels relative to 1 milliwatt in a 600 ohm load.
farad - unit of capacitance (amount of electrons stored in the device for a particular voltage)
gm - transconductance - tube/valve/FET current flow per unit of voltage on the grid/gate.
henry - unit of inductance (amount of magnetic field contained in the core for a particular amperage)
k = kilo, often "kilo-ohm"
mH - millihenry - 1/1000th of a henry, unit of inductance
mS = millisiemens = milliamps per volt (see gm)
ma - milliamp (almost always lower case A), 1/1000th of an amp
mf - microfarad, common in older schematics
mho = 1/ohm = unit of conductance. See S
mmf - milli-microfarad (now nanofarad), 1/1000th of a mf
mmho = confusing, but usually MICRO Mhos (inverse of ohms), older unit of gm in tubes
nf - nanofarad
ohm - unit of resistance (amount of voltage lost to heat for a particular current flow)
pf - picofarad
reactance - "resistance" of a sort, with A/C signals through capacitive and inductive circuit elements. Complex!
ripple - usually in millivolts - the amount of residual power-line A/C remaining on the rectified DC power supply output (at full power)
u = micro, often "microFarads" in circuit diagrams
ua - microamp (u instead of 'mu' greek) 1/1000th of a ma, a millionth of an amp
uf - microfarad
volt - unit of electrical potential

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