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university:courses:electronics:electronics-lab-capacitors [24 Jan 2013 21:12] – created Doug Merceruniversity:courses:electronics:electronics-lab-capacitors [17 Jun 2013 14:45] – minor edit to remove picture reference Doug Mercer
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-====== Capacitors ======+====== Lab Notes on Capacitors ======
  
 ===== Function: ===== ===== Function: =====
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 Examples: Examples:
  
-{{:university:courses:electronics:acap_f1.jpg?100 |}} {{ :university:courses:electronics:acap_f2.jpg?100 |}}+{{:university:courses:electronics:acap_f1.jpg?100 |}} {{:university:courses:electronics:acap_f2.jpg?100 |}}
  
 Circuit Symbol: Circuit Symbol:
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 Electrolytic capacitors are polarized and **they must be connected with the correct orientation**, at least one of their leads will be marked with a + or -. They are not generally damaged by heat when soldering but can overheat and be damaged if connected with the wrong polarity. Electrolytic capacitors are polarized and **they must be connected with the correct orientation**, at least one of their leads will be marked with a + or -. They are not generally damaged by heat when soldering but can overheat and be damaged if connected with the wrong polarity.
    
-There are two designs of electrolytic capacitors; **axial** where the leads are attached to each end (220µF in picture) and **radial** where both leads are at the same end (10µF in picture). Radial capacitors tend to be a little smaller and they stand upright on the circuit board.+There are two designs of electrolytic capacitors; **axial** where the leads are attached to each end and **radial** where both leads are at the same end. Radial capacitors tend to be a little smaller and they stand upright on the circuit board while axial capacitors can have a lower profile on a PC board but may take up more space.
    
 {{ :university:courses:electronics:acap_f4.png?100 |}} {{ :university:courses:electronics:acap_f4.png?100 |}}
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 Tantalum bead capacitors are polarized and have low voltage ratings similar to electrolytic capacitors. They can be more expensive but are very small, so they are used where a large capacitance is needed in a small space. Tantalum bead capacitors are polarized and have low voltage ratings similar to electrolytic capacitors. They can be more expensive but are very small, so they are used where a large capacitance is needed in a small space.
  
-{{ :university:courses:electronics:acap_f5.jpg?100 |}}+{{ :university:courses:electronics:acap_f5.jpg?160 |}}
  
 Modern tantalum bead capacitors are printed with their capacitance and voltage in full. However older ones use a color-code system which has two stripes (for the two digits) and a spot of color for the number of zeros to give the value in µF. The standard color code is used, but for the spot, **grey** is used to mean × 0.01 and **white** means × 0.1 so that values of less than 10µF can be shown. A third color stripe near the leads shows the voltage (yellow 6.3V, black 10V, green 16V, blue 20V, grey 25V, white 30V, pink 35V).  Modern tantalum bead capacitors are printed with their capacitance and voltage in full. However older ones use a color-code system which has two stripes (for the two digits) and a spot of color for the number of zeros to give the value in µF. The standard color code is used, but for the spot, **grey** is used to mean × 0.01 and **white** means × 0.1 so that values of less than 10µF can be shown. A third color stripe near the leads shows the voltage (yellow 6.3V, black 10V, green 16V, blue 20V, grey 25V, white 30V, pink 35V). 
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 Examples: Examples:
  
-{{:university:courses:electronics:acap_f6.jpg?100 |}} {{ :university:courses:electronics:acap_f8.png?250}} {{ :university:courses:electronics:acap_f7.jpg?100 |}}+{{:university:courses:electronics:acap_f6.jpg?100 |}} {{:university:courses:electronics:acap_f7.jpg?100}} 
 +{{:university:courses:electronics:acap_f8.png?250}} 
  
 Circuit symbol: Circuit symbol:
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 {{ :university:courses:electronics:acap_f19.gif?400 |}} {{ :university:courses:electronics:acap_f19.gif?400 |}}
  
-<WRAP centeralign> Figure 6 Capacitor Model </WRAP>>+<WRAP centeralign> Figure 6 Capacitor Model </WRAP>
  
 Stray or “parasitic” capacitance commonly occurs between parallel traces on a PC board or between traces/planes on opposite sides of a PC board. The occurrence and effects of stray capacitance- especially at very high frequencies - are unfortunately often overlooked during circuit modeling and can lead to serious performance problems when the system circuit board is constructed and assembled; examples include greater noise, reduced frequency response, even instability. Stray or “parasitic” capacitance commonly occurs between parallel traces on a PC board or between traces/planes on opposite sides of a PC board. The occurrence and effects of stray capacitance- especially at very high frequencies - are unfortunately often overlooked during circuit modeling and can lead to serious performance problems when the system circuit board is constructed and assembled; examples include greater noise, reduced frequency response, even instability.
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 | Aluminum electrolytic | High | Large values High currents High voltages Small size | High leakage Usually polarized Poor stability Poor accuracy Inductive | | Aluminum electrolytic | High | Large values High currents High voltages Small size | High leakage Usually polarized Poor stability Poor accuracy Inductive |
 | Tantalum electrolytic | High | Small size Large values Medium inductance | Quite high leakage Usually polarized Expensive Poor stability Poor accuracy | | Tantalum electrolytic | High | Small size Large values Medium inductance | Quite high leakage Usually polarized Expensive Poor stability Poor accuracy |
 +
 +==== For more info on passive components see: ====
 +
 +[[http://www.analog.com/static/imported-files/application_notes/500824934643930414583807523874018494695982855668424783486554001060AN348.pdf|AN-348: Avoiding Passive-Component Pitfalls]]
  
 **Return to Lab Activities [[university:courses:electronics:labs|Table of Contents]]** **Return to Lab Activities [[university:courses:electronics:labs|Table of Contents]]**
  
  
university/courses/electronics/electronics-lab-capacitors.txt · Last modified: 03 Jan 2021 22:21 by Robin Getz

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