Digital and electronic inks

Digital and electronic inks

Non-impact printing (NIP) technology ('plateless printing') is becoming popular these days, with the proliferation of computers, office copiers, fax machines and laser printers, and home and office ink jet printers. By definition, NIP accepts electronic input (for example, digital) and uses 'impactless' electrostatic, dielectric inkjet, thermal transfer or magnetic printing technologies to put an image onto substrates. Digital printing is the merging of the graphic design system (scanner or computer) with the printing unit.
Inkjet technology is the fast growing segment in the NIP sector (Chem. Br., August 2000, p39). Here an electrical pulse forces the printer to eject an ink drop. The ink for this purpose has the same general composition as other inks, but has some special characteristics: for example, very small particle sizes are required to pass through the fine nozzle and very low viscosity is needed for free ink flow. Drop on Demand (DOD) and Continuous Ink Jet (CIJ) are the two main inkjet printing technologies. Piezo Ink Jet DOD technology, in which a piezo crystal pushes a drop of the ink when prompted by a frequency regulated energy impulse, dominates the market.
Electronic inks represent the latest development in inks that is expected to change the concept of printing itself. These inks are now used in sign boards, and the display can be changed electronically, without resorting to liquid crystal displays (LCDs) or light emitting diodes (LEDs). Electronic inks change colour when an electric field is applied to them. The ink is made up of tiny bubbles of a dark coloured dye in which light coloured particles are suspended. These plastic-encapsulated particles are printed on a conductive material and some look light and some look dark when electricity is applied, so creating images. Normally the ink is not visible and reveals images only on applying electricity. Microcapsules of proprietary particulate materials mixed with the appropriate binders form the main constituents of these inks.

Capacitor

Capacitor

A device used to store charge in an electrical circuit. A capacitor functions much like a battery, but charges and discharges much more efficiently (batteries, though, can store much more charge).
A basic capacitor is made up of two conductors separated by an insulator, or dielectric. The dielectric can be made of paper, plastic, mica, ceramic, glass, a vacuum or nearly any other nonconductive material. Some capacitors are called electrolytics, meaning that their dielectric is made up of a thin layer of oxide formed on a aluminum or tantalum foil conductor.
Capacitor electron storing ability (called capacitance) is measured in Farads. One Farad is actually a huge amount of charge (6,280,000,000,000,000,000 electrons to be exact), so we usually rate capacitors in microfarads (uF = 0.000,001F) and picofarads (pF = 0.000,000,000,001F ). Capacitors are also graded by their breakdown (i.e., smoke) voltage. Capacitors rated for lower voltages are generally smaller in size and weight; you don't want to use too low a voltage rating, though, unless you enjoy replacing burnt-out capacitors in your creation.
For BEAMbots, you'll need to know about 2 main types of capacitors:

Non-polarized fixed capacitor A non-polarized ("non polar") capacitor is a type of capacitor that has no implicit polarity -- it can be connected either way in a circuit. Ceramic, mica and some electrolytic capacitors are non-polarized. You'll also sometimes hear people call them "bipolar" capacitors.


Polarized fixed capacitor
A polarized ("polar") capacitor is a type of capacitor that have implicit polarity -- it can only be connected one way in a circuit. The positive lead is shown on the schematic (and often on the capacitor) with a little "+" symbol. The negative lead is generally not shown on the schematic, but may be marked on the capacitor with a bar or "-" symbol. Polarized capacitors are generally electrolytics.
Note that you really need to pay attention to correctly hooking a polarized capacitor up (both with respect to polarity, as well as not pushing a capacitor past its rated voltage). If you "push" a polarized capacitor hard enough, it is possible to begin "electrolyzing" the moist electrolyte. Modern electrolytic capacitors usually have a pressure relief vent to prevent catastrophic failure of the aluminum can (but don't bet your eyesight on this).

Capacitor types

 Capacitor types

There are many different types of capacitor that can be used - most of the major types are outlined below:

• Ceramic capacitor:   The ceramic capacitor is a type of capacitor that is used in many applications from audio to RF. Values range from a few picofarads to around 0.1 microfarads. Ceramic capacitors are by far the most commonly used type of capacitor being cheap and reliable and their loss factor is particularly low although this is dependent on the exact dielectric in use. In view of their constructional properties, these capacitors are widely used both in leaded and surface mount formats Read more about the ceramic capacitor
• Electrolytic capacitor:   Electrolytic capacitors are a type of capacitor that is polarised. They are able to offer high capacitance values - typically above 1μF, and are most widely used for low frequency applications - power supplies, decoupling and audio coupling applications as they have a frequency limit if around 100 kHz. Read more about the electrolytic capacitor
• Tantalum capacitor:   Like electrolytic capacitors, tantalum capacitors are also polarised and offer a very high capacitance level for their volume. However this type of capacitor is very intolerant of being reverse biased, often exploding when placed under stress. They must also not be subject to high ripple currents or voltages above their working voltage. They are available in both leaded and surface mount formats. Read more about the tantalum capacitor
• Silver Mica Capacitor:   Silver mica capacitors are not as widely used these days, but they still offer very high levels of stability, low loss and accuracy where space is not an issue. They are primarily used for RF applications and and they are limited to maximum values of 1000 pF or so. Read more about the silver mica capacitor
• Polystyrene Film Capacitor:   Polystyrene capacitors are a relatively cheap form of capacitor but offer a close tolerance capacitor where needed. They are tubular in shape resulting from the fact that the plate / dielectric sandwich is rolled together, but this adds inductance limiting their frequency response to a few hundred kHz. They are generally only available as leaded electronics components.
• Polyester Film Capacitor:   Polyester film capacitors are used where cost is a consideration as they do not offer a high tolerance. Many polyester film capacitors have a tolerance of 5% or 10%, which is adequate for many applications. They are generally only available as leaded electronics components.
• Metallised Polyester Film Capacitor:   This type of capacitor is a essentially a form of polyester film capacitor where the polyester films themselves are metallised. The advantage of using this process is that because their electrodes are thin, the overall capacitor can be contained within a relatively small package. The metallised polyester film capacitors are generally only available as leaded electronics components.
• Polycarbonate capacitor:   The polycarbonate capacitors has been used in applications where reliability and performance are critical. The polycarbonate film is very stable and enables high tolerance capacitors to be made which will hold their capacitance value over time. In addition they have a low dissipation factor, and they remain stable over a wide temperature range, many being specified from -55°C to +125°C. However the manufacture of polycarbonate dielectric has ceased and their production is now very limited. Read more about the polycarbonate capacitor
• Polypropylene Capacitor:   The polypropylene is sometimes used when a higher tolerance is necessary than polyester capacitors offer. As the name implies, this capacitor uses a polypropylene film for the dielectric. One of the advantages of the capacitor is that there is very little change of capacitance with time and voltage applied. They are also used for low frequencies, with 100 kHz or so being the upper limit. They are generally only available as leaded electronics components.
• Glass capacitors:   As the name implies, this type of capacitor uses glass as the dielectric. Although expensive, these capacitors offer very high levels or performance in terms of extremely low loss, high RF current capability, no piezo-electric noise and other features making them ideal for many performance RF applications.
  

Standard Capacitor Values

Over time, a series of standard capacitor values have evolved, just as with resistors and inductors. Capacitors are available in a huge range of package styles, voltage and current handling capacities, dielectric types, quality factors, and many other parameters. Still, they largely hold to this range of values.

Capacitors are one of the four fundamental types of passive electronic components; the other three are the inductor, the resistor, and the memristor. The basic unit of capacitance is the Farad (F).

In order to obtain other values of capacitance, it is necessary to use parallel and/or series combinations. Often, complex combinations are used in order to satisfy multiple requirements such as handling large voltages while still providing the correct amount of capacitance.

If it is necessary to provide occasional tuning of a circuit, then it is necessary to use a variable capacitor. That can take the form of a manually adjusted capacitor, or an electrically tuned capacitor like a varactor diode (varicap).

These fixed capacitor values are the most commonly found
pF	pF	pF	pF	µF	µF	µF	µF	µF	µF	µF
1.0	10	100	1000	0.01	0.1	1.0	10	100	1000	10,000
1.1	11	110	1100
1.2	12	120	1200
1.3	13	130	1300
1.5	15	150	1500	0.015	0.15	1.5	15	150	1500
1.6	16	160	1600
1.8	18	180	1800
2.0	20	200	2000
2.2	22	220	2200	0.022	0.22	2.2	22	220	2200
2.4	24	240	2400
2.7	27	270	2700
3.0	30	300	3000
3.3	33	330	3300	0.033	0.33	3.3	33	330	3300
3.6	36	360	3600
3.9	39	390	3900
4.3	43	430	4300
4.7	47	470	4700	0.047	0.47	4.7	47	470	4700
5.1	51	510	5100
5.6	56	560	5600
6.2	62	620	6200
6.8	68	680	6800	0.068	0.68	6.8	68	680	6800
7.5	75	750	7500
8.2	82	820	8200
9.1	91	910	9100

Common Capacitor Working Voltages (DC), By Capacitor Type
Ceramic	Electrolytic	Tantalum	Mylar (Polyester)	Mylar (Metal Film)
	10V	10V
16V	16V	16V
		20V
25V	25V	25V
	35V	35V
50V	50V	50V	50V
	63V
100V	100V		100V
	160V
			200V
	250V			250V
	350V
			400V	400V
	450V
600V
				630V
1000V

Circuit Schematic Symbols

Note: The schematics symbols for most major electrical components can be found in this table. However, each component may have numerous possible representations. In cases where there is more than one common symbol we have tried to give an alternate representation.

COMPONENT	SYMBOL	ALTERNATE
Ammeter
And Gate
Antenna, Balanced
Antenna, General
Antenna, Loop, Shielded
Antenna, Loop, Unshielded
Antenna, Unbalanced
Attenuator, Fixed
Attenuator, Variable
Battery
Capacitor, Feedthrough
Capacitor, Fixed, Nonpolarized
Capacitor, Fixed, Polarized
Capacitor, Ganged, Variable
Capacitor, General
Capacitor, Variable, Single
Capacitor, Variable, Split-Stator
Cathode, Cold
Cathode, Directly Heated
Cathode, Indirectly Heated
Cavity Resonator
Cell
Circuit Breaker
Coaxial Cable
Crystal, Piezoelectric
Delay Line
Diode, General
Diode, Gunn
Diode, Light-Emitting
Diode, Photosensitive
Diode, Photovoltaic
Diode, Pin
Diode, Varactor
Diode, Zener
Directional Coupler
Exclusive-Or Gate
Female Contact, General
Ferrite Bead
Fuse
Galvanometer
Ground, Chassis
Ground, Earth
Handset
Headphone, Double
Headphone, Single
Inductor, Air-Core
Inductor, Bifilar
Inductor, Iron-Core
Inductor, Tapped
Inductor, Variable
Integrated Circuit
Inverter
Jack, Coaxial
Jack, Phone, 2-Conductor
Jack, Phone, 2-Conductor Interrupting
Jack, Phone, 3-Conductor
Jack, Phono
Key, Telegraph
Lamp, Incandescent
Lamp, Neon
Male Contact, General
Microphone
Nand Gate
Negative Voltage Connection
Nor Gate
Operational Amplifier
Or Gate
Outlet, Utility, 117-V
Outlet, Utility, 234-V
Photocell, Tube
Plug, Phone, 2-Conductor
Plug, Phone, 3-Conductor
Plug, Phono
Plug, Utility, 117-V
Plug, Utility, 234-V
Positive Voltage Connection
Potentiometer
Probe, Radio-Frequency
Rectifier, Semiconductor
Rectifier, Silicon-Controlled
Rectifier, Tube-Type
Relay, DPDT
Relay, DPST
Relay, SPDT
Relay, SPST
Resistor
Resonator
Rheostat
Saturable Reactor
Shielding
Signal Generator
Speaker
Switch, DPDT
Switch, DPST
Switch, Momentary-Contact
Switch, Rotary
Switch, SPDT
Switch, SPST
Terminals, General, Balanced
Terminals, General, Unbalanced
Test Point
Thermocouple
Thyristor
Transformer, Air-Core
Transformer, Iron-Core
Transformer, Tapped Primary
Transformer, Tapped Secondary
Transistor, Bipolar, npn
Transistor, Bipolar, pnp
Transistor, Field-Effect, N-Channel
Transistor, Field-Effect, P-Channel
Transistor, Metal-Oxide, Dual-Gate
Transistor, Metal-Oxide, Single-Gate
Transistor, Photosensitive
Transistor, Unijunction
Tube, Diode
Tube, Pentode
Tube, Photomultiplier
Tube, Tetrode
Tube, Triode
Unspecified Component
Voltmeter
Wattmeter
Wires
Wires, Connected, Crossing
Wires, Not Connected, Crossing