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*LM35 Temperature Sensor
 
*LM35 Temperature Sensor
 
*555 Timer astable oscillator
 
*555 Timer astable oscillator
*[[current mirror]]
+
*diode for forward drop bias voltage
**Transistor Current Mirror
+
*row and collumn connection
 
*charge pump
 
*charge pump
*diode for forward drop bias voltage
+
*transformer
 +
*voltage multiplier
 
*diode logical or
 
*diode logical or
 +
*RC timer
 +
*diode full wave bridge
 
*H Bridge
 
*H Bridge
  
An H bridge is an electronic circuit that causes current to flow in one direction or the other ( from a single ended power supply ).  Often used for motor control [[motor driver]].
+
An H bridge is an electronic circuit that causes current to flow in one direction or the other ( from a singel ended power supply ).  Often used for motor control [[motor driver]].
 
It is an electronic double pole double throw switch.
 
It is an electronic double pole double throw switch.
**[http://code.rancidbacon.com/Electronics] See Section on ''H-Bridge''
+
[http://code.rancidbacon.com/ElectronicsElectronics] See Section on ''H-Bridge''
**[http://roko.ca/robotics/h-bridge-fundamentals H-Bridge Fundamentals]
+
 
*integrator
+
*Simple Oscillator circuits
*diode full wave bridge
+
*Current mirrors
*RC timer
 
 
*RF Mixers
 
*RF Mixers
*diode rounding circuit
+
*Tranistor Current Mirror
*row and collumn connection
 
*sample and hold  http://en.wikipedia.org/wiki/Sample_and_hold
 
*Simple Oscillator circuits
 
*transformer
 
*voltage multiplier and voltage doubler
 
 
 
 
 
 
*[[Colpitts Oscillator]]
 
*[[Colpitts Oscillator]]
  
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See the sections on:  Op amp Non Inverting Amplifier, Op amp Unity Gain Buffer ....
 
See the sections on:  Op amp Non Inverting Amplifier, Op amp Unity Gain Buffer ....
  
*[http://www.amplifiersite.com/ AmplifierSite.com]
+
[http://www.amplifiersite.com/ AmplifierSite.com]
*[http://electronicdesign.com/Portals/0/TI_Wp_AudioGuide_Aug2011.pdf  Guide to a lot of amplifier and other audio circuits]
 
  
 
== Current Sense Resistor ( Shunt Resistance ) ==
 
== Current Sense Resistor ( Shunt Resistance ) ==
  
A current Sense Resistor is a low value of resistor that is placed in series with some other circuit.  We can then measure the voltage across the resistor to compute the current.  If the resistor has a low value compared to other components we can ignore the effect on the circuit.  We use the word shunt when the voltage is measured by a device that has a fairly low resistance itself.  We then have to do a more careful calculation of how the current is shared by the two devices.
+
A current Sense Resistor is a low value of resistor that is placed in parallel with some other circuit.  We can then measure the voltage across the resistor to compute the current.  If the resistor has a low value compared to other components we can ignore the effect on the circuit.  We use the word shunt when the voltage is measured by a device that has a fairly low resistance itself.  We then have to do a more careful calculation of how the current is shared by the two devices.
  
 
Circuit:
 
Circuit:
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Where
 
Where
 
*R shunt resistor used to sense the current  ( and divert it from the meter ).  Usually much less in value than the internal resistance of the meter.
 
*R shunt resistor used to sense the current  ( and divert it from the meter ).  Usually much less in value than the internal resistance of the meter.
*METER  meter or other device used to measure the voltage across the shunt resitor.  Often the resistance of the meter is ignored ( if high ).
+
*METER  meter or other device used to measure the voltage across the shunt reistor.  Often the resistance of the meter is ignored ( if high ).
 
*BATTERY  a battery or other voltage source.
 
*BATTERY  a battery or other voltage source.
*BULB  an incandescent light bulb
 
  
 
Discussion:
 
Discussion:
  
In the old days a sensitive meter, say 50 mv full scale, would be used with a set of shunt, some looking like metal bars, to measure a wide range of currents, up to and exceeding 50 amps.  Sometimes a meter came with a set of shunts for measuring different currents.  See links.  A completely different way to measure currents is to use a hall effect sensor.
+
In the old days a sensitive meter, say 50 mv full scale, would be used with a set of shunt, some looking like metal bars, to measure a wide range of currents, up to and exceeding 50 amps.
  
 +
There are many inaccuracies in this entry. A current sense resistor must go in series in order to carry the same current as the load. Putting the resistor in series guarantees that it will carry the same current as the load because of Kirchoff Current Law (KCL).  The current in the current sense resistor can then be determined from the voltage across it by Ohm's Law, and this will be the same as the current in the load. The technique described in this entry would only work if the the impedance of the network which the sense resistor was connected across was precisely known. However if the impedance of the network is known, there is no need for a current sense resistor as Ohms Law could give the current directly. Finally, the schematic omits a load and the symbol for the battery is upside down (assuming the author intended ground to be the lowest node on the schematic and voltages to be positive). -LPM
  
Links to More information:   
+
More information:   
 
#[http://www.scienceshareware.com/bg-current-monitoring.htm  Scienceshareware.com's How A Precision Resistor Is Used to Measure / Calculate Current and Power in an Electrical Circuit.]
 
#[http://www.scienceshareware.com/bg-current-monitoring.htm  Scienceshareware.com's How A Precision Resistor Is Used to Measure / Calculate Current and Power in an Electrical Circuit.]
 
#[http://www.maxim-ic.com/appnotes.cfm/appnote_number/746/ High-Side Current-Sense Measurement: Circuits and Principles]
 
#[http://www.maxim-ic.com/appnotes.cfm/appnote_number/746/ High-Side Current-Sense Measurement: Circuits and Principles]
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Discussion:
 
Discussion:
  
The idea here is that R2 is a current sense resistor.  When the sense voltage across R2 reaches about .7 ( for silicon transistors ) Q2 begins to conduct and diverts the base drive from Q1 cutting its output current.  So the max. current from the circuit is reached when I*R2 = .7.  This circuit can be used to protect amplifiers ( including push pull amps. ), power supplies and other circuits; or it can be used as a constant current circuit.  It is not a precision circuit, but it is cheap, simple, and effective circuit.
+
The idea here is that R2 is a current sense reistor.  When the sense voltage across R2 reaches about .7 ( for silicon transistors ) Q2 begins to conduct and diverts the base drive from Q1 cutting its output current.  So the max. current from the circuit is reached when I*R2 = .7.  This circuit can be used to protect amplifiers ( including push pull amps. ), power supplies and other circuits; or it can be used as a constant current circuit.  It is not a precision circuit, but it is cheap, simple, and effective circuit.
  
  
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#[http://freecircuitdiagram.com/2008/08/27/variable-adjustable-current-limiter-circuit/ Variable (Adjustable) Current Limiter Circuit ]  This is a bit more complicated version using a transistor to drive a darlington transistor, with the limit being adjustable.
 
#[http://freecircuitdiagram.com/2008/08/27/variable-adjustable-current-limiter-circuit/ Variable (Adjustable) Current Limiter Circuit ]  This is a bit more complicated version using a transistor to drive a darlington transistor, with the limit being adjustable.
 
#[http://forum.allaboutcircuits.com/showthread.php?t=32709 Current Source for Resistance Measurement]
 
#[http://forum.allaboutcircuits.com/showthread.php?t=32709 Current Source for Resistance Measurement]
#[http://powerampdesign.net/images/AN-12_The_Problem_with_Current_Limit.pdf The Problem with Current Limit] Discusses this circuit as applied to a power amplifier.
+
#[http://docs.google.com/gview?a=v&q=cache%3Axoux8Ax7B_UJ%3Awww.powerampdesign.net%2Fimages%2FAN-12_The_Problem_with_Current_Limit.pdf+amplifier+current+limit&hl=en&gl=us&pli=1 The Problem with Current Limit] Discusses this circuit as applied to a power amplifier.
 
#[http://www.instructables.com/id/Constant-current-LED-Tester/ Constant current LED-Tester] Simple application of the circuit as an LED tester.
 
#[http://www.instructables.com/id/Constant-current-LED-Tester/ Constant current LED-Tester] Simple application of the circuit as an LED tester.
  
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The amount of ripple in a simple circuit like this can be determined from the supply frequency voltage, output current, and the capacitance.  The amount of time without any input voltage is 1/2f.  Given an output current I, the charge transferred is is I/2f.  The voltage sag is then just the charge divided by the capacitance, or I/2fC.  An inductor added to this circuit will compensate for voltage sag by inducing a voltage if the current starts to drop.
 
The amount of ripple in a simple circuit like this can be determined from the supply frequency voltage, output current, and the capacitance.  The amount of time without any input voltage is 1/2f.  Given an output current I, the charge transferred is is I/2f.  The voltage sag is then just the charge divided by the capacitance, or I/2fC.  An inductor added to this circuit will compensate for voltage sag by inducing a voltage if the current starts to drop.
  
<!----------More Information:
+
More Information:
 
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== High Side Switch ==
 
 
This circuit switches a load at the high side away from ground.  With a simple switch it is easy, just wire the switch into the high side.  Using transistors is not so easy.  There are integrated circuits that make it easy again. But this is not a basic circuit.  Contrast with [http://opencircuits.com/Basic_Circuits_and_Circuit_Building_Blocks#Transistor_Low_Side_Switch Transistor Low Side Switch]
 
  
 
== Light Emitting Diode ( with current limiting resistor ) ==
 
== Light Emitting Diode ( with current limiting resistor ) ==
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*[http://www.evilmadscientist.com/article.php/throw Some thoughts on throwies] interesting notes on the resistor normally used with an LED.
 
*[http://www.evilmadscientist.com/article.php/throw Some thoughts on throwies] interesting notes on the resistor normally used with an LED.
  
== Op Amp Non Inverting Amplifier ==
+
== Op amp Non Inverting Amplifier ==
 
Use this circuit where the signal you have is not as large as you want, or cannot provide enough current.  It is called non inverting because a positive input produces a positive output ( An inverting amplifier produces a negative output when given a positive input ).
 
Use this circuit where the signal you have is not as large as you want, or cannot provide enough current.  It is called non inverting because a positive input produces a positive output ( An inverting amplifier produces a negative output when given a positive input ).
  
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More Information:
 
More Information:
 
*[[OpAmp Links]]
 
*[[OpAmp Links]]
<!--------------------------------------------------------------------->
 
 
== Op Amp Precision Rectifier ==
 
Draft - Incomplete  Use this circuit where you wish to get very accurate rectification.  Precision means that most of the usual forward voltage drop of a diode circuit goes away.  Results look good down into the mv range.
 
 
 
Circuit:
 
[[Image:opamp_pr.png | Op Amp Precision Rectifier ]]
 
 
Where
 
*D1 Diode....
 
*R2 resistor 2 or any other 2 terminal component.....
 
OPAMPA  Any general purpose op amp, often connected to + and - power supplies
 
 
Discussion:
 
more comming
 
 
Th
 
 
More Information:
 
*[[OpAmp Links]]
 
*[http://sound.westhost.com/appnotes/an001.htm Precision Rectifiers Rod Elliott (ESP)]
 
 
 
 
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Discussion:
 
Discussion:
 
The values of RIN and RFB are not very critical and are normally 0 ohms, just a straight connection.  The op amp here is a quad or 4 op amp part, we are using just one section of it.  Power needs to be supplied to pin 8 and 4 in the usual way for op amps.
 
The values of RIN and RFB are not very critical and are normally 0 ohms, just a straight connection.  The op amp here is a quad or 4 op amp part, we are using just one section of it.  Power needs to be supplied to pin 8 and 4 in the usual way for op amps.
This circuit uses very large feedback (unity) and for this reason has poor stability margins. This may cause the output to go into oscillations when connected to certain loads (typically capacitive). Check the datasheet of individual opamps for details and remedies.
 
  
 
More information:   
 
More information:   
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Discussion:
 
Discussion:
  
I you have a lot of components that use the same voltage put them in parallel.  This is how most lights in a house are wired.  Each individual light can be turned on and off without changing the current or voltage in the other lights.  With a bit of math you can show that the two resistors act like one resistor of value R = (R1*R2)/(R1 + R2).  When you need a resistor of a different value than you have you can sometimes “make it up” using a parallel connection of resistors you do have.  Two identical resistors in parallel are equivalent to one of half the resistance.  A parallel circuit can have more than 2 resistors, there can be 3, 4, ... You can find out more about parallel circuits in the references.  This circuit should be contrasted with the Series Circuit.  Parallel circuits can also be used with other components, the equations vary, for capicators the capacitances add in a parallel circuit.
+
I you have a lot of components that use the same voltage put them in parallel.  This is how most lights in a house are wired.  Each individual light can be turned on and off without changing the current or voltage in the other lights.  With a bit of math you can show that the two resistors act like one resistor of value R = R1 + R2 /( R1 * R2 ).  When you need a resistor of a different value than you have you can sometimes “make it up” using a parallel connection of resistors you do have.  Two identical resistors in parallel are equivalent to one of half the resistance.  A parallel circuit can have more than 2 resistors, there can be 3, 4, ... You can find out more about parallel circuits in the references.  This circuit should be contrasted with the Series Circuit.  Parallel circuits can also be used with other components, the equations vary, for capicators the capacitances add in a parallel circuit.
  
 
More information:   
 
More information:   
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*[http://www.seattlerobotics.org/encoder/mar97/basics.html  Very Basic Circuits]
 
*[http://www.seattlerobotics.org/encoder/mar97/basics.html  Very Basic Circuits]
 
*[http://www.dnatechindia.com/index.php/Tutorials/8051-Tutorial/Switch-Interfacing.html Interfacing Switch to Microcontroller]
 
*[http://www.dnatechindia.com/index.php/Tutorials/8051-Tutorial/Switch-Interfacing.html Interfacing Switch to Microcontroller]
*[http://blog.makezine.com/archive/2009/07/ask_make_pull-up_resistor.html Ask MAKE: Pull-up resistor]
 
  
 
Debouncing Discussion:
 
Debouncing Discussion:
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Discussion:
 
Discussion:
 
Just a variation on the Pull Up and Switch.
 
Just a variation on the Pull Up and Switch.
 
Links:
 
 
* [http://roguescience.org/wordpress/?page_id=11 Roguescience Arduino Tutorials 4.2 Pull-up/down resistors, debouncing]
 
<!--------------------------------------------------------------------->
 
 
<!--------------------------------------------------------------------->
 
 
== Rectifier - Power ==
 
this is a stubb, almost no useful content
 
 
Use this circuit when you want to convert AC to DC at significant current in order to provide DC power to another circuit component, it can be also used as a very low precision "precision rectifier".  Basically similar circuits are sometimes used as demodulators for AM signals.
 
 
Discussion:
 
 
There are many variations of this circuit, sometimes in combination with center tapped transformers, sometimes with multiple diodes ( as in bridge circuits ).
 
 
<!--------------------------------------------------------------------->
 
 
== Rectifier - Signal and Absolute Vaue Circuit ==
 
this is a stubb, almost no useful content
 
 
Use this circuit when you want to know the peak voltage of an AC of time varying DC voltage of just its absolute value.  It typically differes from a power rectifier in that the circuit needs
 
its own source of power, it does not pass thru the power of the input voltage, it also differes in that the typical voltage drop of the power diode ( in the range of .5 to 2 volts ) is largely eliminated. This is a signal processing circuit.
 
 
Discussion:
 
There are a ton of ways to do this a common way is to include a diode with a forward voltage drop in the feedback loop of an operational amplifier.  There are lots of circuits that can be used, see links for discussion of different circuits and there advantages and dis.
 
 
 
Links:
 
 
* [http://www.analog.com/library/analogDialogue/archives/44-04/absolute.html More Value from Your Absolute Value Circuit—Difference Amplifier Enables Low-Power, High-Performance Absolute Value Circuit]
 
* [http://www.ti.com/lit/an/sboa068/sboa068.pdf PRECISION ABSOLUTE VALUE CIRCUITS By David Jones (520) 746-7696, and Mark Stitt]
 
* [http://i.stack.imgur.com/kUIO3.jpg Images]
 
 
 
 
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*[[Relays]]  
 
*[[Relays]]  
*[http://en.wikipedia.org/wiki/Solid_state_relay Solid state relay]
 
 
*[http://en.wikipedia.org/wiki/snubber "snubber" from Wikipedia, the free encyclopedia]
 
*[http://en.wikipedia.org/wiki/snubber "snubber" from Wikipedia, the free encyclopedia]
 
*[http://en.wikipedia.org/wiki/flyback_diode "flyback diode" from Wikipedia, the free encyclopedia]
 
*[http://en.wikipedia.org/wiki/flyback_diode "flyback diode" from Wikipedia, the free encyclopedia]
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Discussion:
 
Discussion:
  
The circuit above is very basic.  Practical circuits normally include filter capacitors on both the input and the output.  Most regulators protect against both over temperature and over current.  Regulators come in various voltages both positive and negative.  They also vary in maximum current output. There are also adjustable regulators, ways of using regular regulators as adjustable ones, and ways of boosting the current output.  The spec sheets often describe how to do these things.  Voltage regulators “use up” a couple of volts of the input voltage, low drop out regulators have use less, cost more.  It is a good idea to check the specification for any regulator you are going to use.  The LM78xx ( positive ) and LM79xx ( negative ) are quite common.  Most three terminal devices are "linear" they disappate the excess power in the input as heat, thus they are not very efficient.  Switching regulators can be much more efficient, but are not normally 3 terminal devices ( although you and make it one by putting the entire circuit in a box with just 3 wires coming out ).
+
The circuit above is very basic.  Practical circuits normally include filter capacitors on both the input and the output.  Most regulators protect against both over temperature and over current.  Regulators come in various voltages both positive and negative.  They also vary in maximum current output. There are also adjustable regulators, ways of using regular regulators as adjustable ones, and ways of boosting the current output.  The spec sheets often describe how to do these things.  Voltage regulators “use up” a couple of volts of the input voltage, low drop out regulators have use less, cost more.  It is a good idea to check the specification for any regulator you are going to use.  The LM78xx ( positive ) and LM79xx ( negative ) are quite common.
  
 
More information:   
 
More information:   
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*[http://en.wikipedia.org/wiki/7805 7805 From Wikipedia, the free encyclopedia]
 
*[http://en.wikipedia.org/wiki/7805 7805 From Wikipedia, the free encyclopedia]
 
*[http://www.tkk.fi/Misc/Electronics/circuits/psu_5v.html Simple 5V power supply for digital circuits]
 
*[http://www.tkk.fi/Misc/Electronics/circuits/psu_5v.html Simple 5V power supply for digital circuits]
 +
  
 
== Transistor Low Side Switch ==
 
== Transistor Low Side Switch ==
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A low side switch is one which switches a circuit on and off at the ground or low side of the circuit.  The advantage of a low side switch is that when using a transistor as the switch the voltage to drive the transistor is itself a low voltage.  It is often the easy way to drive LEDS, motors, and other high current devices from such low power devices as PIC output ports.  Low side switches are popular and there are many integrated circuits for them as well as this circuit.
 
A low side switch is one which switches a circuit on and off at the ground or low side of the circuit.  The advantage of a low side switch is that when using a transistor as the switch the voltage to drive the transistor is itself a low voltage.  It is often the easy way to drive LEDS, motors, and other high current devices from such low power devices as PIC output ports.  Low side switches are popular and there are many integrated circuits for them as well as this circuit.
  
Circuit with switch:
+
Circuit:
 
 
[[Image:low_ss.png | Transistor Low Side Switch ]]
 
 
 
Circuit with transistor:
 
  
 
[[Image:Tran_lss.jpg | Transistor Low Side Switch ]]
 
[[Image:Tran_lss.jpg | Transistor Low Side Switch ]]
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An example calculation would be nice, and will appear later.
 
An example calculation would be nice, and will appear later.
  
This circuit is sometimes called "grounded-emitter configuration". Note that this circuit can be realized with a bipolar transistor or fet.  The bipolar transistor has a lower drive voltage ( usually well under 2 volts ) the fet can easily need 10 volts of drive -- use a logic level fet to reduce the drive voltage.
+
This circuit is sometimes called "grounded-emitter configuration".
 
 
Some characteristics:
 
 
 
*Useful ( with simple circuits and common components ) for currents from a max of a few amps and voltages of 10's of volts.
 
*Can be very fast, into the Mega Hz.
 
*Can be very cheap at the low end.
 
*Small, simple.
 
*Some integrated circuit drivers like the  are basically multiple transistor low side switches.
 
 
 
  
 
More Information:
 
More Information:
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== Transistor High Side Switch ==
 
== Transistor High Side Switch ==
  
Use this circuit when you wish to turn a load on and off with a voltage at a low current.  Note that low side of the load is grounded.  The voltage to turn on the switch is equal to the supply voltage ( or perhaps just a bit larger )
+
Use this circuit when you wish to turn a load on and off with a voltage at a low current.  Note that low side of the load is grounded.  The voltage to turn on the switch is equal to the supply voltage ( or perhaps just a bit larger )
  
A high side switch is one which switches a circuit on and off at the supply voltage or high side of the circuit (the high side can be negative, it is a side away from ground).  The advantage of a high side switch is that the load is grounded on one side.  Compared to the low side switch it needs a higher voltage to drive it, but it also eliminates one resistor of that circuit.  It the voltage to drive it is available it may be the circuit of choice.  It is often the easy way to drive leds motors and other high current devices from such low power devices as PIC output ports.  
+
A high side switch is one which switches a circuit on and off at the supply voltage or high side of the circuit.  The advantage of a high side switch is that the load is grounded on one side.  Compared to the low side switch it needs a higher voltage to drive it, but it also eliminates one resistor of that circuit.  It the voltage to drive it is available it may be the circuit of choice.  It is often the easy way to drive leds motors and other high current devices from such low power devices as PIC output ports.  
 
 
Here is a high side switch with a push button:
 
 
  
 
Circuit:
 
Circuit:
  
[[Image:high_ss.png | High Side Switch ]]
+
[[Image:tran_hss.png |thumb|450px| Transistor High Side Switch ]]
 
 
 
 
   
 
Circuit with a transistor:
 
 
 
[[Image:tran_hss.png | Transistor High Side Switch]]
 
       
 
 
 
  
 
Where
 
Where
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No resistor is needed into the base of the transistor because as the load draws current the voltage at the base will rise and limit the base current.  The input voltage should be about equal to VPLUS_VDD, high compared to that needed for the low side switch.
 
No resistor is needed into the base of the transistor because as the load draws current the voltage at the base will rise and limit the base current.  The input voltage should be about equal to VPLUS_VDD, high compared to that needed for the low side switch.
  
This high side switch usually requires the base voltage of Q to be VPLUS_VDD plus the turn-on voltage of the transistor to turn all the way on. Another approach to the high side switch that requires a lower turn-on voltage is to use a PNP transistor as the switch. The base of the PNP is pulled up to VPLUS_VDD and connected to the collector of a small signal NPN transistor, Q2. Q2's emitter is connected to ground and its base is connected to the input signal through a current limiting resistor -- now the problem is that a high voltage is required to turn the switch off.
+
This high side switch usually requires the base voltage of Q to be VPLUS_VDD plus the turn-on voltage of the transistor to turn all the way on. Another approach to the high side switch that requires a lower turn-on voltage is to use a PNP transistor as the switch. The base of the PNP is pulled up to VPLUS_VDD and connected to the collector of a small signal NPN transistor, Q2. Q2's emitter is connected to ground and its base is connected to the input signal through a current limiting resistor.
 
 
 
 
=== bootstrap circuit ===
 
 
 
Often H-bridges use n-FETs in all 4 arms, to reduce cost.
 
Unfortunately, power n-FETs require a gate voltage much higher -- many power n-FETs require 10 V higher -- than both of their other two legs in order to keep them turned hard on (necessary for efficient power H-bridges).
 
Since the drain of the high-side n-FET is generally already connected to the highest voltage available from the batteries,
 
where are we going to find that even higher voltage?
 
Often we use a bootstrap circuit.
 
(see
 
Mamadou Diallo from Texas Instruments.
 
[http://www.ti.com/lit/an/slua887/slua887.pdf "Bootstrap Circuitry Selection for Half-Bridge Configurations".
 
2018.
 
)
 
 
 
Historically
 
The Intel 4004 uses a bootstrap circuit[http://insanity4004.blogspot.com/2015/10/puzzling-out-bootstrap-load_13.html]
 
which is apparently one of several reasons
 
the 4004 has a minimum clock rate (maximum cycle time).
 
Reece Pollack is translating the design to a static-logic implementation[http://insanity4004.blogspot.com/2012/09/full-circle.html].
 
(a fully-static system makes it possible to pause the system indefinitely,
 
which is very convenient for debugging).
 
Today we have several alternatives to bootstrap circuits:
 
* If you're building digital logic out of discrete transistors, you might as well replace the 2-transistor bootstrap load circuit with an actual physical discrete resistor, which works better (?).
 
* If you're building digital logic out of FPGAs or full-custom ASICs, you're probably using CMOS -- both nFET and pFET -- and a single nFET works better than a 2-p-FET bootstrap load, and a single pFET works better than a 2-n-FET bootstrap load.
 
* If you're building a H-bridge, even today it is often better to use all-n-FET rather than both n-FET and p-FET; the bootstrap circuit gives a minimum PWM frequency (maximum PWM cycle time) and a minimum and maximum duty cycle (one step less than 100%); replacing that circuit with an independent oscillator and charge pump allows you to go all the way to 100% forward or 100% reverse.
 
 
 
 
 
  
 
== Transistor Emitter Follower ==
 
== Transistor Emitter Follower ==
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*R_LOAD represents the resistance of the load
 
*R_LOAD represents the resistance of the load
 
*Q is a npn bipolar transistor  
 
*Q is a npn bipolar transistor  
*VPLUS_VDD  is the power supply for the Load
+
*VPLUS_VDD  is the power supply for the LED
  
 
The current to drive the circuit is approximately the current to drive the load divided by the beta of the transistor.  Use a Darlington connected transistor for a very high beta.
 
The current to drive the circuit is approximately the current to drive the load divided by the beta of the transistor.  Use a Darlington connected transistor for a very high beta.
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*[http://en.wikipedia.org/wiki/Common_collector Common collector From Wikipedia, the free encyclopedia]
 
*[http://en.wikipedia.org/wiki/Common_collector Common collector From Wikipedia, the free encyclopedia]
 +
  
 
== Transistor -- Push Pull Circuit ==
 
== Transistor -- Push Pull Circuit ==
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*[http://chungyan5.no-ip.org/vc/trunk/AltiumDesigner6ProjectFiles.zip?root=7segment_LEDs&view=log AltiumDesigner6ProjectFiles]
 
*[http://chungyan5.no-ip.org/vc/trunk/AltiumDesigner6ProjectFiles.zip?root=7segment_LEDs&view=log AltiumDesigner6ProjectFiles]
 
*[http://www.dnatechindia.com/index.php/Tutorials/8051-Tutorial/7-Seg-Interfacing.html Interfacing Seven Segment to Microcontroller]
 
*[http://www.dnatechindia.com/index.php/Tutorials/8051-Tutorial/7-Seg-Interfacing.html Interfacing Seven Segment to Microcontroller]
i need a clear explanation about schmitt trigger and also need the operation details about that circuit...if i give the input of the schmitt trigger is 0v means what is the output of  the circuit?
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== Schmitt Trigger ==
 +
Use this circuit when you want to sense if an input is either high or low.  The circuit elmininate inputs that are "in between" and stops small noise signals from causing the input to rapildy oscillating from high to low.
 +
 
 +
 
 +
Circuit:
 +
[[Image:opamp_st.png | Schmitt Trigger ]]
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 +
Where
 +
*RIN input resistor -- when this inputs more current than the positive feedback resistor the output switches to the voltage at the input, else it stays at the output voltage it has already reached. Typically lower in value than RFB.
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*RFB positive feedback resistor the output voltage is feed back to the input and keeps the output at its current voltage.
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 +
 
 +
Discussion:
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 +
The circuit is used to switch between two states even in the presence of noise.  This is an somewhat unusual op amp circuit as it uses positive not negative feedback. See the references for a better explanation and variations on the circuit.
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Schmidt Triggers are also available as integrated circuits which require no external components.
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More Information:
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*[[OpAmp Links]]
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== Oscillators ==
 
== Oscillators ==
Line 729: Line 625:
  
 
Used to generate a voltage that depends upon light level.  With the LDR on the "high side" the voltage will go up when the amount of light goes up.
 
Used to generate a voltage that depends upon light level.  With the LDR on the "high side" the voltage will go up when the amount of light goes up.
You need to use a resistor in series with the light dependent resistor, this combination lets a variable current flow through the circuit.  The voltage across the resistor will vary with the light brightness ( so will the voltage across the LDR, the two will total the input voltage. )  What size resistor should you use?  A rule of thumb:  Put the LDR in medium brightness and measure its resistance with a ohm meter.  Use that value resistor then in medium light you will get 1/2 the input voltage at the output.
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You need to use a resistor in series with the light dependent resistor, this combination lets a variable current flow through the circuit.  The voltage across the resistor will vary with the light brightness ( so will the voltage across the LDR, the two will total to input voltage. )  What size resistor should you use?  A ruel of thumb:  Put the LDR in medium brightness and mesure its resistance with a ohm meter.  Use that value resistor then in medium light you will get 1/2 the input voltage at the output.
  
 
Circuit:
 
Circuit:
Line 768: Line 664:
 
*[http://itp.nyu.edu/physcomp/sensors/Schematics/WheatstoneBridge Wheatstone Bridge]
 
*[http://itp.nyu.edu/physcomp/sensors/Schematics/WheatstoneBridge Wheatstone Bridge]
 
*[http://physics.kenyon.edu/EarlyApparatus/Electrical_Measurements/Capacitance_Bridge/Capacitance_Bridge.html Capacitance Bridge] This one is an antique.
 
*[http://physics.kenyon.edu/EarlyApparatus/Electrical_Measurements/Capacitance_Bridge/Capacitance_Bridge.html Capacitance Bridge] This one is an antique.
 
== current mirror ==
 
 
(FIXME: fill in details)
 
 
[[Wikipedia: current mirror]] http://en.wikipedia.org/wiki/Current_mirror
 
  
 
== Further Reading ==
 
== Further Reading ==
Line 788: Line 678:
 
shows a "simple" noninverting gain circuit,
 
shows a "simple" noninverting gain circuit,
 
and explains what all the "extra" parts do.
 
and explains what all the "extra" parts do.
 
* Philip C. Todd. "Snubber Circuits: Theory , Design and Application". 1993. [http://www.ti.com/lit/an/slup100/slup100.pdf] has more complex snubber circuits.
 
* [http://electronics.stackexchange.com/questions/17731/choosing-components-for-a-triacs-snubber "Choosing components for a triac's snubber"] has more complex snubber circuits.
 
  
  
 
[[Category:Components]][[Category:Schematics]]
 
[[Category:Components]][[Category:Schematics]]

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