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tutorials:learn:powersupply:index.html [2010/10/25 22:59]
ladyada
tutorials:learn:powersupply:index.html [2016/01/28 18:05] (current)
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 Here is the power supply that is used in many apple products: Here is the power supply that is used in many apple products:
  
-{{:private:​m8943.jpg|}}+{{  :tutorials:​learn:​powersupply:m8943.jpg?​nolink  ​|}}
  
 Here is a classic 'wall wart' that comes with many consumer electronics:​ Here is a classic 'wall wart' that comes with many consumer electronics:​
  
-{{http://​www.ladyada.net/​images/​metertutorial/​wart_t.jpg}}+{{  http://​www.ladyada.net/​images/​metertutorial/​wart_t.jpg?​nolink ​  }}
  
 This is a massive power supply that's in a PC, usually you dont see this unless you open up the PC and look inside for the big metal box This is a massive power supply that's in a PC, usually you dont see this unless you open up the PC and look inside for the big metal box
  
-{{:private:​pcsupply.jpg?​500|}}+{{  :tutorials:​learn:​powersupply:​pcsupply.jpg?​nolink&500  |}}
  
 All these power supplies have one thing in common - they take high voltage 120V or 220V AC power and **regulate** or **convert** it down to say 12V or 5V DC. This is important because the electronics inside of a computer, or cell phone, or video game console dont run at 120V and they don't run on AC power! ​ All these power supplies have one thing in common - they take high voltage 120V or 220V AC power and **regulate** or **convert** it down to say 12V or 5V DC. This is important because the electronics inside of a computer, or cell phone, or video game console dont run at 120V and they don't run on AC power! ​
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 ====== AC/DC ===== ====== AC/DC =====
  
-{{:​tutorials:​learn:​powersupply:​acdc.png?​350|}}+{{  :​tutorials:​learn:​powersupply:​acdc.png?​nolink&350  |}}
  
 So the power coming out of your wall is high voltage AC but microcontrollers and servos and sensors all want low voltage DC. How shall we make it work? Converting between AC power and DC power requires different techniques depending on what the input and output is. We'll refer to this table So the power coming out of your wall is high voltage AC but microcontrollers and servos and sensors all want low voltage DC. How shall we make it work? Converting between AC power and DC power requires different techniques depending on what the input and output is. We'll refer to this table
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 | Low Voltage AC (eg. 20VAC) ​ | Low voltage DC (eg 5VDC)  |  Half or full wave rectifier ​ | Very inexpensive (just a diode or two)  | Not isolated ​ |  Practically all consumer electronics that have transformer-based supplies ​ | | Low Voltage AC (eg. 20VAC) ​ | Low voltage DC (eg 5VDC)  |  Half or full wave rectifier ​ | Very inexpensive (just a diode or two)  | Not isolated ​ |  Practically all consumer electronics that have transformer-based supplies ​ |
 | High Voltage AC (eg. 120V-220VAC) ​ | Low voltage DC (eg 5VDC)  |  Transformer & rectifier ​ \\ Combination of High->​Low AC & Low AC->Low DC  | Fairly inexpensive ​ |  Kinda heavy, output is not precise, efficiency is so-so  |   Every chunky wall-wart contains this   | | High Voltage AC (eg. 120V-220VAC) ​ | Low voltage DC (eg 5VDC)  |  Transformer & rectifier ​ \\ Combination of High->​Low AC & Low AC->Low DC  | Fairly inexpensive ​ |  Kinda heavy, output is not precise, efficiency is so-so  |   Every chunky wall-wart contains this   |
-| High Voltage AC (eg. 120V-220VAC) ​ | Low voltage DC (eg 5VDC)  |  Switching supply ​ |  Light-weight,​ output is often precise |  Expensive! ​ |  Every slimmer wall-wart contains this  |+| High Voltage AC (eg. 120V-220VAC) ​ | Low voltage DC (eg 5VDC)  |  Switching supply ​ | Light-weight,​ output is often precise ​ |  Expensive! ​ |  Every slimmer wall-wart contains this  |
  
 Basically, to convert from AC to AC we tend to use a transformer. To convert from AC to DC we use a transformer + diodes (rectifier) or a switching supply. The former is inexpensive (but not very precise) and the later is expensive (but precise). Guess which one you're more likely to find in a cheaply-made device? :) Basically, to convert from AC to AC we tend to use a transformer. To convert from AC to DC we use a transformer + diodes (rectifier) or a switching supply. The former is inexpensive (but not very precise) and the later is expensive (but precise). Guess which one you're more likely to find in a cheaply-made device? :)
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 To understand converters, its best to go through their design step by step. Let's start at the top with: To understand converters, its best to go through their design step by step. Let's start at the top with:
  
-   * [[transformeracdc.html|Part 1. The Transformer-based AC/DC power supply]]+   * [[http://​www.ladyada.net/​learn/​powersupply/​transformeracdc.html|Part 1. The Transformer-based AC/DC power supply]]
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