Junior Laboratory I
Junior Laboratory I ECE 617
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This 6 page Class Notes was uploaded by Miss Felicita Stiedemann on Thursday October 29, 2015. The Class Notes belongs to ECE 617 at University of New Hampshire taught by Staff in Fall. Since its upload, it has received 19 views. For similar materials see /class/231691/ece-617-university-of-new-hampshire in Computer Engineering at University of New Hampshire.
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Date Created: 10/29/15
E6 Series Values nanofarads microfarads 00 00000 The E6 series 10 15 22 33 47 68 Standard values picofarads pF 10 15 22 33 47 68 nanofarads nF 001 0015 0022 0033 0047 0068 150 220 330 470 680 01 015 022 033 047 068 microfarads 11F 000001 0000015 0000022 0000033 0000047 0000068 00001 000015 000022 000033 000047 000068 1000 1500 2200 3300 4700 6800 0001 00015 00022 00033 00047 00068 Industry Standard Markings 100 150 220 330 470 680 101 151 221 331 471 681 102 152 222 332 472 682 10000 15000 22000 33000 47000 68000 001 0015 0022 0033 0047 0068 103 153 223 333 473 683 100000 150000 220000 330000 470000 680000 100 150 220 330 470 680 01 015 022 033 047 068 104 154 224 334 474 684 1000000 1500000 2200000 3300000 4700000 6800000 1000 1500 2200 3300 4700 6800 15 22 33 47 68 105 155 225 335 475 685 10000000 15000000 22000000 33000000 47000000 68000000 10000 15000 22000 33000 47000 68000 15 22 33 47 68 100000000 100000 100 Function Capacitors store electric charge They are used with resistors in timing circuits because it takes time for a capacitor to ll with charge They are used to smooth varying DC supplies by acting as a reservoir of charge They are also used in lter circuits because capacitors easily pass AC changing signals but they block DC constant signals Capacitance This is a measure ofa capacitor39s ability to store charge A large capacitance means that more charge can be stored Capacitance is measured in farads symbol F However 1 F is very large so pre xes are used to show the smaller values Three prefixes multipliers are used u micro n nano and p pico u means 10396 millionth so 1000pF 1F n means 10399 thousandmillionth so 1000nF 1uF p means 103912 millionmillionth so 1000pF 1nF Capacitor values can be very difficult to nd because there are many types of capacitor with different labelling systems There are many types of capacitor but they can be split into two groups polarised and unpolarised Each group has its own circuit symbol Polarised capacitors large values 1uF Examples Circuit Symbol Electrolytic Capacitors Electrolytic capacitors are polarised and they must be connected the correct way round at least one of their leads will be marked or They are not damaged by heat when soldering There are two designs ofelectrolytic capacitors axial where the leads are attached to each end 220uF in picture and radial where both leads are at the same end 10uF in picture Radial capacitors tend to be a little smaller and they stand upright on the circuit board It is easy to nd the value ofelectrolytic capacitors because they are clearly printed with their capacitance and voltage rating The voltage rating can be quite low 6V for example and it should always be checked when selecting an electrolytic capacitor It the project parts list does not specify a voltage choose a capacitor with a rating which is greater than the project39s power supply voltage 25V is a sensible minimum for most battery circuits Tantalum Bead Capacitors Tantalum bead capacitors are polarised and have low voltage ratings like electrolytic capacitors They are expensive but very small so they are used where a large capacitance is needed in a small size Modern tantalum bead capacitors are printed with their capacitance and voltage in full However older ones use a colourcode system which has two stripes for the two digits and a spot of colour forthe number ofzeros to give the value in uF The standard colour code is used but forthe spot grey is used to mean x 001 and white means x 01 so that values of less than 10uF can be shown A third colour stripe near the leads shows the voltage yellow 63V black 10V green 16V blue 20V grey 25V white 30V pink 35V For example blue grey black spot means 68uF For example blue grey white spot means 68uF For example blue grey grey spot means 068uF Unpolarised capacitors small values up to 1pF Examples 39 Circuit symbol Small value capacitors are unpolarised and may be connected either way round They are not damaged by heat when soldering except for one unusual type polystyrene They have high voltage ratings of at least 50V usually 250V or so It can be difficult to nd the values ofthese sma capacitors because there are many types of them and several different labelling systems Many small value capacitors have their value printed but without a multiplier so you need to use experience to work out what the multiplier should be For example 01 means 01uF 100nF Sometimes the multiplier is used in place of the decimal point For example 4n7 means 47nF Capacitor Number Code A number code is often used on small capacitors where printing is dif cult I I the 1st number is the 1st digit the 2nd number is the 2nd digit the 3rd number is the number of zeros to give the capacitance in pF lgnore any letters they just indicate tolerance and voltage rating For example 102 means 1000pF 1nF not 102pF For example 472J means 4700pF 47nF J means 5 tolerance Colour Code Capacitor Colour Code A colour code was used on polyester capacitors for many years It is now obsolete but of course there are many still around The colours should be read like the resistor code the top three colour bands giving the value in pF Ignore the 4th band tolerance and 5th band voltage rating For example brown black orange means 10000pF 10nF 001 pF Note that there are no gaps between the colour bands so 2 identical bands actually appear as a wide band 0 1 2 3 4 5 6 7 8 9 For example wide red yellow means 220nF 022uF Polystyrene Capacitors This type is rarely used now Their value in pF is 47m normally printed without units Polystyrene capacitors can be damaged by heat when soldering it melts the polystyrene so you should use a heatsink such as a crocodile clip Clip the heatsink to the lead between the capacitor and the joint Real capacitor values the E3 and E6 series You may have noticed that capacitors are not available with every possible value for example 22pF and 47pF are readily available but 25pF and 50pF are not Why is this Imagine that you decided to make capacitors every 10pF giving 10 20 30 40 50 and so on That seems ne but what happens when you reach 1000 It would be pointless to make 1000 1010 1020 1030 and so on because for these values 10 is a very small difference too small to be noticeable in most circuits and capacitors cannot be made with that accuracy To produce a sensible range of capacitor values you need to increase the size of the 39step39 as the value increases The standard capacitor values are based on this idea and they form a series which follows the same pattern for every multiple often The E3 series 3 values for each multiple often 10 22 47 then it continues 100 220 470 1000 2200 4700 10000 etc Notice how the step size increases as the value increases values roughly double each time The E6 series 6 values for each multiple often 10 15 22 33 47 68 then it continues 100 150 220 330 470 680 1000 etc Notice how this is the E3 series with an extra value in the gaps The E3 series is the one most frequently used for capacitors because many types cannot be made with very accurate values