Abbreviations A-mW

Abbreviations used in Electronics A to mW

A (amp) Ampere AC Alternating current AC/DC Alternating current or direct current A/D Analog to digital ADC Analog-to-digital converter AF Audio frequency AFT Automatic fine tunung AFC Automatic frequency control AFC Automatic flow controller, used in controlling the flow of gasses under pressure into a vacuum system AGC Automatic gain control Ah Ampere hour Ai Current gain AM Amplitude modulation AM/FM Amplitude modulation or Frequency modulation AMM Analog multimeter antilog Antilogarithm Ap Power gain apc Automatic phase control Av Voltage gain AVC Automatic volume control AWG American wire gauge B Flux density BCD Binary coded decimal bfo Beat frequency oscillator BJT Bipolar junction transistor BW Bandwidth c Centi (10-2) C Capacitance or capacitor CAD Computer aided design CAM Computer aided manufacture CATV Cable TV CB Common base configuration CB Citizen's band CC Common collector CE Common emitter cm Centimeter cmil Circular mil CPU Central processing unit C (Q) Coulomb CR cr Junction diode CRO Cathode ray oscilloscope CRT Cathode ray tube CT Total capacitance cw Continuous transmission d Deci (10-1) D/A or D-A Digital to analog DC Direct current Di or Di Change in current DIP Dual in-line package DMM Digital multimeter DPDT Double pole double throw Dt or Dt Change in time DTL Diode transistor logic Dv or Dv Change in voltage DVM Digital voltmeter E DC or Erms Difference in potential e Instantaneous difference in potential ECG Electrocardiogram ECL Emitter coupled logic EHF Extremely high frequency EHV Extra high voltage ELF Extremely low frequency EMF Electromotive force EMI Electromagnetic interference EW Electronic warfare f Frequency FET Field effect transistor FF Flip Flop fil Filament FM Frequncy modulation fr Frequency at resonance fsk frequency-shift keying FSD Full scale deflection G Gravitational force G Conductance G Giga (109 ) H Henry H Magnetic field intensity H Magnetizing flux h hecto (102 ) h Hybrid HF High frequency hp Horsepower Hz Hertz I Current i Instantaneous current IB DC Base current IC DC Collector current IC Integrated circuit Ie Total emitter current Ieff Effective current IF Intermediate frequency Imax Maximum current Imin Minimum current I/O Input/output IR Infrared IR Resistor current IS Secondary current IT Total current JFET Junction field effedt transistor K Coefficient of coupling k Kilo (103 ) kHz Kilohertz kV Kilovolt kVA Kilovoltampere kW Kilowatt kWh Kilowatt-hour L Coil, inductance LC Inductance-capacitance LCD Liquid crystal display L-C-R Inductance-capacitance-resistance LDR Light-dependent resistor LED Light emitting diode LF Low frequency LM Mutual inductance LNA Low noise amplifier LO Local oscillator LSI Large scale integration LT Total inductance M Mega (106 ) M Mutual conductance MI Mutual inductance m Milli (10-3 ) mA Milliampere mag Magnetron max Maximum MF Medium frequency mH Millihenry MHz Megahertz min Minimum mm Millimeter mmf Magnetomotive force MOS Metal oxide semiconductor MOSFET Metal oxide semiconductor field effect transistor MPU Microprocessor unit MSI Medium scale integrated circuit mV Millivolt mW Milliwatt

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Digital Lock

Description

A multiple input combination loack using CMOS counter IC's. Flexibility and code change is allowed by changing output connections.

TO see the circuit diagram CLICK HERE

Notes

The circuit above above makes use of the CMOS 4017 decade counter IC. Each depression of a switch steps the output through 0 - 9. By coupling the output via an AND gate to the next IC, a predefined code has to be input to create the output. Each PBS switch is debounced by two gates of a CMOS4001 quad 2-input NOR gate. This ensures a clean pulse to the input of each CMOS 4017 counter. Only when the correct number of presses at PBS A will allow PBS B to become active. This is similar for PBS C and PBS D. At IC4, PBS D must be pressed 7 times. Then PBS C is again pressed 7 times, stepping from output 1 to output 8. The AND gate formed around CMOS4081 then goes high, lighting the LED. The Reset switch can be pressed at any time. Power on reset is provided by the 100n capacitor near the reset switch.



Unfortunately, this board was part of a much larger project containing multiple power supplies. One day whilst working on another circuit , I slipped with a wire and splashed 24 volts DC onto this board. There was a small spark, and puff of smoke before all this chips were cooked! If anyone does consider building such a circuit, then my advice would be to stop and look in your local electronic parts catalogue. There are now dedicated combination lock IC's with combinations many times greater than this circuit. Incidentally the numberof combinations offered here is 10 x 10 x 10 x 10 x 9 = 90,000.

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Frost Alarm

Description

A simple thermistor triggered switch with adjustable threshold. It triggers with cold temperatures so may be used as a frost alarm or cold temperature switch.

Circuit Notes

The thermistor used has a resistance of 15k at 25°C and 45k at 0° Celsius. The 100k pot allows this circuit to trigger over a wide range of temperatures.

If using a different thermistor then the control should match the new thermistor at its highest resistance, or be higher in value. The op-amp in this circuit is the ubiquitous 741. It may be catalogued as LM741, CA741 etc, all types will work. In this circuit it is used as a comparator. The non-inverting input (pin 3) is biased to half the supply voltage. The non-inverting input is connected to the junction of the thermistor and potentiometer. The control is adjusted so that the circuit is on when the thermistor is at the required temperature range. Once the thermistor is outside the temperature range its resistance alters and the op-amp output changes from near full supply to around 1 or 2 volts dc. There is insufficient voltage to turn on the transistor and the relay will not energise.

A slight amount of hysteresis is provided by inclusion of the 270k resistor. This prevents rapid switching of the circuit when the temperature is near to the switching threshold.

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Infra Red Link

Description

This is a battery powered IR Link which may be used in more than one room. The standby current is extremely low - giving a good battery life; and by shutting down in the presence of extraneous IR radiation it copes with the problem of excessive output current.

Notes:-

This circuit is not powered directly from the battery. When a remote control signal is received, the energy stored in C2 drives the emitter diode. At the same time, Q1 switches on briefly to allow the battery to recharge C2. The green LED shows that the circuit is transmitting; and the yellow LED confirms that C2 has been topped-up.
There is unwanted IR radiation in both daylight and tungsten lighting. To minimize its effect use an opaque housing and do not make the opening too large. (Try a horizontal slot measuring 2 cm X 1.5 cm.) Shade the receiver diodes by mounting them side-by-side a few centimetres deep, inside the case. The depth of shading required will depend on the lighting conditions. (Try 5 cm to start with). To reduce the effects of visible light, use receiver diodes with a built-in daylight filter ( Maplin CY91Y). Or cover the opening using a small piece of dark transparent plastic. Part of the display panel from a scrap VCR is ideal. Position the unit out of direct light and avoid reflective surfaces. If all else fails, adjust VR1 to reduce sensitivity. What you are aiming for is to ensure that in standby mode Q2 remains switched off so that C2 retains its charge. If unwanted radiation does reach the receiver it will not result in a large output current. C2 simply discharges and the circuit shuts down. When the source of the unwanted radiation is removed the unit may be reset by interrupting the power supply for a few seconds or by pushing the (optional) reset button. If you do neither then it will reset itself after about an hour when C2 has recharged through R7. With two receiver diodes wired in parallel, the operating range is up to about 1 meter. The exact distance depends on the remote you are using and on the position of VR1 (start by setting it about halfway). Correctly focused, a plastic lens from a small magnifying glass will extend the distance.

I used the high gain version of the BC337 because that was what I had available. However, the only transistor whose gain is likely to be important is the BC547C. For the infrared emitter I used a TIL38 (Maplin YH70M) at the end of 12 meters of alarm cable. However, the diode from a scrap remote control should be worth trying also. Two diodes wired in series will give improved output performance.
The circuit was designed with a small 9-volt alkaline battery in mind (PP3, MN1604, 6LR61) but the prototype worked well at 6-volts using four AA batteries. The standby current was too small to measure reliably. An earphone socket makes the unit portable; so it can be used in more than one room. If you can obtain the style of socket in the diagram (Maplin HF82D), its normally closed switch can be converted to a normally open switch by releasing the inner contact as shown. This means that it will act as an on/off switch when you unplug the lead; and because it allows you to interrupt the power supply, there is no need for a reset button.

Circuit Layout:

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IR Remote Control Modulation Detector

Description

A circuit to extract and measure the modulated carrier of an Infra Red remote control. Note that the circuit does not physically separate control pulses from modulation, but amplifies the completereceived signal allowing the waveform to be displayed ideally on an oscilloscope or a frequency counter. Modulation frequencies between 1kHz and several MHz may be measured.



Basic IR Remote Control Info:

All remote controls employing Infra Red technology use digital control signals that are modulated with a higher frequency carrier wave. The carrier wave, which is invisible to the human eye is commonly modulated between 36 and 38KHz. However,some equipment i.e. Satellite decoders may use even higher modulating frequencies. The digital control signals are relatively slow compared to the carrier frequency, typically 100 to 200 bps (bits per second). The control pulses are sent in serial format and turn the carrier on and off.

Notes

Fortunately, the control pulses of a typical remote control are long, compared to the faster modulated IR carrier wave. This very fact allows at least a few complete waveforms to be captured and measured, either on an oscilloscope or with a digital counter. As the carrier is continually being modulated, the waveform will need to be displayed with a digital counter has a variable trigger or with an oscilloscopes manual trigger control. Light interference from nearby fluorescent light sources may also interfere with the signal,so, for this reason, I recommend to place the remote control within a few inches of the photodiode.

The detector is an IR photodiode, type TIL100. This is reverse biased via the 22k resistor and produces small changes in current when subjected to light in the IR spectrum. Ambient or steady light will produce a constant current through the photo diode, a remote control produces an alternating waveform. The input signal is capacitively coupled to the first BC549C amplifier stage via a 10n capacitor. The capacitor will stop ambient light from passing,but not changes in light intensity. A signal of a few microamps can be passed from the photo diode into the amplifier. The high current gain of a BC549C and a medium load resistor will produce a voltage waveform that may be suitably displayed on an oscilloscope at this point. The magnitude will vary with the proximity from remote control to photo diode and also with type of remote control, hence an accurate reading is not possible. For anyone with an oscilloscope set the volts/division control to maximum and work backwards to minimum sensitivity.

Displaying on a Frequency Counter

The lower sensitivity of a frequency counter requires the signal to be processed further. To remove the previous amplifiers DC bias voltage, but allow only a strong modulated carrier wave to pass the last stage operates in Class D mode. In Class D amplifiers, there are no bias components, the signal from the previous stage is used as the bias source. Therefore there will be no signal output at the collector of the rightmost BC549C under quiescent conditions, but only with a strong IR signal ( in close proximity to the photo diode). The output transistor will be on when a positive peak arrives, and off for a negative peak. This crude method has also turned the original sinusoidal waveform into a digital one, there will be some phase shift from input to output, but the period of the waveform can still be measured. The signal can be buffered even further, if needed, the black triangle represents one gate of a CMOS 4050 buffer. As control pulses are combined with the carrier, a frequency meter or counter is best set to measure the period of the wave, rather than the frequency. As frequency is the reciprocal of periodic time, divide 1 by the reading on the meter or counter.



As can be seen (use a right click and choose your internet browsers view image) the periodic waveform is 26.11us. This equates to 1/26.11u = 0.0382 Mhz or 38.2KHz in the case of this Aiwa remote control.

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Basic Constants & Standards

Constants and Standards

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DIELECTRIC CONSTANTS OF MATERIALS

The dielectric constants of most materials vary for different ternperatures and frequencies. Likewise, small differences in the composition of materials will cause differences in the dielectric constants. A list of materials and the approximate range (where available) of their dielectric constants are given in Table 2-1. The values shown are accurate enough for most applications. The dielectric constants of sorne materials (such as quarfz, Styrofoam, and Teflon) do not change appreciably with frequency.

Table 2-1 Dielectric constants of Matrials
Material	Dielectric Constants (Approx.)		Material	Dielectri Constantc (Approx.)
Air Amber Asbestos Fiber Bakelite (asbestos base) Bakelite (mica filled) Barium Titanote Beeswax Cambric (varnished) Carbon Tetrachloride Colluloid Collulose Acetate Durite Ebonite Epoxy Resin Ethyl Alcohol (obsolute) Fiber Formica Glass (electrical) Glass (photogrophic) Glass (Pyrex) Glass (window) Gutta Percha Isolantite Lucite Mico (olectrical) Mica (cloor Indio) Mica (filled phenolic) Micaglass (titanium dioxide) Micarta Mycolex Neoprene	1.0 2.6-2.7 3.1-4.8 5.0-22 4,5-4.8 100-1250 2.4-2.8 4.0 2.17 4.0 2.9-4.5 4.7-5.1 2.7 3.4-3.7 6.5-25 .0 3.6-6.0 3.8-14.5 7.5 4,6-5.0 7.6 2.4-2.6 6.1 2.5 4.0-9.0 7.5 4.2-5.2 9.0-9.3 3.2-5.5 7.3-9.3 4.0-6.7		Nylon Poper (dry) Paper (paraffin coated) Paraffin (solid) Plexiglas Polycorbonate Polyethylene Polyimide Polystyrene Porcelain (dry process) Porcelain (wet process) Quartz Quartz (fused) Rubber (hard) Ruby Mica Selenium (amorphous) Shellac (natural) Silicone (glass) (molding) Silicone (glass) (laminate) Slate Soil (dry) Steatite (ceramic) Steatite (low loss) Styrofoam TefIon Titanium Dioxide Vaseline Vinylite Water (distilled) Waxes, Mineral Wood (dry)	3.4-22.4 1.5-3.0 2.5-4.0 2.0-3.0 2.6-3.5 2.9-3.2 2.5 3.4-3.5 2.4-3.0 5.0-6.5 5.8-6.5 5.0 3.78 2.0-4.0 5.4 6.0 2.9-3.9 3.2-4.7 3.7-4.3 7.0 2.4-2.9 5.2-6.3 4.4 1.03 2.1 l00 2.16 2.7-7.5 34-78 2.2-2.3 1.4-2.9

METRIC SYSTEM

The international system of units developed by the General Conference on Weights and Measures (abbreviated CGPM), commonly called the metric system, is the basis for a worldwide

Table 2-2. SI Base and Supplementary Units
Quantity	Unit	Symbol
length mass time electric current thermodynamic temperature amount of substance luminous intensity plane angle solid angle	meter kilograrn second ampere kelvin * mole candela radiant † steradiont †	m kg s A K mol cd rad sr

* The degree Celsius is also used for expressing temperature. † Supplementory units.

Table 2-3. SI Derived Units With Special Names
Quantity	Unit	Symboll	Formula
frequency (of a periodic phenomenon) force pressure, stress energy, work, quantity of heat power, radiant flux quantity of electricity electric charge electric potential, potential difference, electromotive force capacitance electric resistance concluctance magnetic flux magnetic flux density incluctance luminous flux illuminance activity (of radionuclides) obsorbed close	hertz newton pascal joule watt coulomb volt farad ohm siemens weber tesla henry lumen lux becquerel gray	Hz N Pa J W C V F W S Wb T H Im Ix Bq Gy	I/s kg'm/s2 N/m2 N*m J/s A*s W/A C/V V/A AN V*s Wb/m2 Wb/A cd*sr Im/m2 I/s J/kg

standardization of units. This International System of Units (abbreviated SI) is divided into three classes-base units, supplementary units; and derived units.

Units and Symbols

The seven base units and the two supplementary units with their symbols are given in Table 2-2. Derived units are formed by combining base units, supplementary units and other derived units. Certain derived units have special names and symbols. These units, their symbols and formulas, are given in Table 2-3. Other common derived units,- and their symbols, are given in Table 2-4.

Table 2-4. Common SI Derived Units
Quantity	Unit	Symbol
acceleration angular acceleration angular velocity area concentration (of amount of substance) current density density, mass electric charge density electric field strength electric flux density energy density entropy heat capacity heat flux density irradiance luminance magnetic field strength molar energy molar entropy molar heat capacity moment of force permeability permittivity radiance radiant intensity specific heat capacity specific energy special entropy specific volume surface tension thermal conductivity velocity viscosity, dynamic viscosity, kinernatic volume wovenumber	meter per second squored radian per second squared radion per second square meter mole per cubic meter ampere per square meter kilogram per cubic meter coulomb per cubic meter volt per meter coulomb per square meter joule per cubic meter joule per kelvin joule per kelvin watt per square meter candela per square meter ampere per meter joule per mole joule per mole kelvin joule per mole kelvin newton meter henry per meter farad per meter watt per square meter steradian watt per steradion joule per kilogram kelvin joule per kilogrom joule per kilogram kelvin cubic meter per kilogrom newton per meter watt per meter kelvin meter per second poscal second square meter per second cubic meter l per meter	m/s2 rad/s2 rad/s m2 mol/m3 A/m2 kg/m3 C/m3 V/m C/m2 J/m3 J/K J/K W/M2 cd/m2 A/m J/mol J/(mol*K) J/(mol*K) N-m H/m F/m W/(m2 -sr) W/sr J/(kg*K) J/kg J/(kg*K) M3/kg N/m W/(m*K) m/s Pa*s m2/s m 3 I/m

Some units, not part of SI are so widely used they are impractical to abandon. These units Listed in Table 2-5) are acceptable for continued uses.

Table 2-5 Units in Use With SI
Quantity	Unit	Symbol	Value
Time Plane angle volume Mass Area (land)	minute hour day week, month, year degree minute second liter metric ton hectare	min h d ° ' " L* t ha	1 min = 60 s 1 h = 60 min = 3600 s 1 d = 24h = 86,400 s l = (p/I 80) rad 1' = (1/60)° = (p 10800) rad 1" = (1/60)' = (p/648 000) rad 1 L = 11 dml = 10-3 M3 1 t = 103 kg 1 ha = 104 M2

*The international symbol for liter is the lowercase 'l', which can be confused with the number "1." Therefore the symbol "L' or spelling out the term liter is advisable.

Prefixes

The sixteen prefixes in Table 2-6 are used to form multiples and submultiples of the SI units. The use of more than one prefix is to be avoided (e.g. pico instead of micromicro and giga instead of kilomega). The preferred pronunciation of the terms is also included in the table. The accent is on the first syllable of each prefix.

Table 2-6. Metric Prefixes
Muftiplication Factor	Prefix	Abbreviation	Pronunciation
1018 1015 1012 109 106 103 102 10 10-1 10-2 10-1 10-6 10-9 10-12 10-15 10-16	exa peta tera giga mega kilo hecto deka deci centi milli micro nano pico fernto atto	E P T G M k h* da* d* C* m µ n p f a	ex'a (a as in a bout) as in petal as in terrace jig'a (a as in a bout) as in mega phone as in kilowatt heck' toe deck'a (a as in a bout) as in decimal as in sentiment as in military as in microphone nan'oh (an as in ant) peek'oh fern'toe (fem as in feminine) as in anatomy

The use 0f hecto, deka, deci, and centi should be avoided for SI unit multiples except for area and volume, and the nontechnical use of centimeter for body and clothing measurements.

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Standard color codes

Resistor Color Code Chart

A handy reference perfect for students and anyone learning electronics. Capacitor Identification Codes There are no international agreements in place to standardise capacitor identification. Most plastic film types (Figure1) have printed values and are normally in microfarads or if the symbol is n, nanofarads. Working voltage is easily identified. Tolerances are upper case letters: M = 20%, K = 10%, J = 5%, H = 2.5% and F = ± 1pF. Figure 1 A more difficult scheme is shown in Figure 2 with examples. The unit is picofarads and the third number is a multiplier. A capacitor coded 474K63 means 47 × 10000 pF which is equivalent to 470000 pF or 0.47 microfarads. K indicates 10% tolerance. 50, 63 and 100 are working volts. Figure 2 Ceramic disk capacitors have many marking schemes. Capacitance, tolerance, working voltage and temperature coefficient may be found. See Figure 3. Capacitance values are given as number without any identification as to units. (uF, nF, pF) Whole numbers usually indicate pF and decimal numbers such as 0.1 or 0.47 are microfarads. Odd looking numbers such as 473 is the previously explained system and means 47 nF. Figure 3 Figure 4 shows some other miscelaneous schemes. Figure 4

STANDARD WIRING COLOR CODES

Electronic applications (as established by the Electronic Industries Association – EIA):
Insulation Color . . . . . . .Circuit type
Black . . . . . . . . . . . . . . .Chassis grounds, returns, primary leads
Blue . . . . . . . . . . . . . . . .Plate leads, transistor collectors, FET drain
Brown . . . . . . . . . . . . . .Filaments, plate start lead
Gray . . . . . . . . . . . . . . . .AC main power leads
Green . . . . . . . . . . . . . . .Transistor base, finish grid, diodes, FET gate
Orange . . . . . . . . . . . . . .Transistor base 2, screen grid
Red . . . . . . . . . . . . . . . .B plus dc power supply
Violet . . . . . . . . . . . . . . .Power supply minus
White . . . . . . . . . . . . . . .B – C minus of bias supply, AVC – AGC return
Yellow . . . . . . . . . . . . . .Emitters-cathode and transistor, FET source

Stereo Audio Channels

Insulation Color . . . . . . .Circuit type
White . . . . . . . . . . . . . . .Left channel high side
Blue . . . . . . . . . . . . . . . .Left channel low side
Red . . . . . . . . . . . . . . . .Right channel high side
Green . . . . . . . . . . . . . . .Right channel low side

AF Transformers (audio)

Insulation Color . . . . . . .Circuit type
Black . . . . . . . . . . . . . . .Ground line
Blue . . . . . . . . . . . . . . . .Plate, collector, or drain lead. End of primary winding.
Brown . . . . . . . . . . . . . .Start primary loop. Opposite to blue lead.
Green . . . . . . . . . . . . . . .High side, end secondary loop.
Red . . . . . . . . . . . . . . . .B plus, center tap push - pull loop.
Yellow . . . . . . . . . . . . . .Secondary center tap.

IF Transformers (Intermediate Frequency)

Insulation Color . . . . . . .Circuit type
Blue . . . . . . . . . . . . . . . .Primary high side of plate, collector, or drain lead.
Green . . . . . . . . . . . . . . .Secondary high side for output.
Red . . . . . . . . . . . . . . . .Low side of primary returning B plus.
Violet . . . . . . . . . . . . . . .Secondary outputs.
White . . . . . . . . . . . . . . .Secondary low side.

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