Electronic Engineering Dictionary

Modulator. A device that imposes a signal on a carrier. A device that produces modulation; that is, a device that varies the amplitude, frequency, or phase of an ac signal. A circuit used in servo-systems to convert a dc signal to an ac signal. The output ac signal is a sine wave at the frequency of the ac reference voltage. The amplitude of the output is directly related to the amplitude of the dc input. The circuits function is opposite to that of a DEMODULATOR. In radar, it produces a high-voltage pulse that turns the transmitter on and off. Also see the separate section on Definitions relating to Radar.

Modulator Switching Diode. Controls the on (discharge) and off (charge) time of the modulator.

Module. A circuit or portion of a circuit packaged as a removable unit. A separable unit in a packaging scheme displaying regularity of dimensions.

Modulus. A number representing the states a counter will cycle through.

Monitor. An LCD or CRT display which is used with a computer or some other system. A display not receiving TV signals.

Monochrome. Black and White Television.

Mono Jack. A jack designed to handle one channel of sound. There are many different sizes and styles of mono jacks, one example is shown below. Example Op Amp Mono amplifier circuit.

1/8 inch Mono Phono Jack

Monolithic Capacitor. A capacitor formed on the silicon substrate of an integrated circuit.

Monolithic Circuit. A circuit where all elements (resistors, transistors, and so forth) associated with the circuit are fabricated inseparably within a continuous piece of material (called the substrate), usually silicon.

Monolithic IC. ICs that are formed completely within a semiconductor substrate. Silicon chips.

Monolithic Microwave Integrated Circuit. [MMIC]

Monophonic. Audio playback or receiving audio on only one channel.

Monostable. A circuit or component that has one stable state and one quasi-stable state. A one-shot. A circuit that takes one stable state until it receives a trigger pulse, and than moves to a quasi-stable state.

Monostable Multivibrator. A multivibrator that has one steady state [graphic in side-bar]. A signal (trigger) must be applied to cause change of states. A 74221 One Shot IC. Also refer to a 555 Monostable Circuit, or Transistor Monostable Multivibrator Circuit.

Monotonic. Meaning of increasing order. With Analog to Digital Converters Monotonic means the output does not count backwards with an increasing analog signal. With Digital to Analog Converters Monotonic implies and increase in output current for each increment in the binary word of the input.

Monotonicity. Is the measure of a component [DAC or ADC] to be Monotonic. DAC Manufacturers.

Morse Code. An out-dated form of communication using 'dot' and 'dashes'. A dash is equal to three dots. Spaces between parts of the same letter is equal to 1 dot. Space between 2 letters is equal to 3 dots. Spaces Between 2 words is equal to 5 dots. The chart provides Morse codes for letters A to Z & numbers 1 to 0.

Morse Code

The Federal Communications Commission [FCC] has dropped the requirement to know Morse Code for all amateur radio licenses in 2007. The US navy may still use Morse code for ship-to-ship signal light communications. Morse code was also used as an international standard for maritime communication until 1999, when it was replaced by the Global Maritime Distress Safety System [GMDSS]. The International Telecommunication Union [ITU] dropped the Morse code requirement in 2003.

MOSFET. [Metal Oxide Field Effect Transistor] A semiconductor device that contains diffused source and drain regions on either side of a P- or N-channel area. Also contains a gate insulated from the channel area by silicon-oxide. Operates in either the depletion or the enhancement mode. See MOSFET and FET Manufacturers.

MOSFET

MOS Transistor. The general term to refer to a Metal Oxide Semiconductor Transistor, and refers to either an N-Type or P-Type device with any type of structure. See MOS symbols below.

Most Significant Digit. [MSD] The MSD is the digit whose position within a given number expression has the greatest weighting power.

Motor. A machine that converts electrical energy to mechanical energy. It is activated by ac or dc voltage, depending on the design. Manufacturers of Motors.

Electrical Motor

Motherboard. A Printed Circuit Board [PCB] that is large compared to the smaller PCBs that attach to it. The Motherboard holds smaller size boards called Expansion Cards [as in PC mother-board] or Daughter cards, or Mezzanine cards [as in embedded systems]. Manufacturers of Motherboards

Motorboating. A type of low frequency sound head from an amplifier in [unwanted] oscillation. Noise generated in a audio frequency amplifier so called because of the similarity to the sound of a motor.

Motor Load. Any device driven by a motor. Typical loads are drills, saws, water pumps, rotating antennas, generators, and so forth. The speed and power capabilities of a motor must be matched to the speed and power capabilities of the motor load.

Motor Reaction. The force created by generator armature current that tends to oppose the normal rotation of the armature.

Motor Start Capacitor. A capacitor which is in series with a motors startup winding only while the motor is being started, other wise it is automatically removed from the circuit. A Motor-Start Capacitor increases the phase shift of the winding allowing the motor to start under heavy load. May also be called a Motor Run Capacitor; however a Motor-Run Capacitor is left in the circuit.

Motor Starter. Large resistive devices placed in series with dc motor armatures to prevent the armature from drawing excessive current until armature speed develops counter emf. The resistance is gradually removed from the circuit either automatically or manually as motor speed increases.

Mounting Hardware. Any hardware required to secure a device or component to another device in the system. Companies making mounting hardware.

Mounting Hole. The cut-out in a panel or other component required for a part. An example panel cutout for a BNC connector is shown to the right.

BNC Cut-out