Quantcast Current Regulators

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Custom Search
 
  
 
4-44 Q33. In figure 4-37, the voltage drop across RS and R1 determines the amount of base-emitter ____ for Q1. Q34. In figure 4-39, view A, when there is an increase in the input voltage, the forward bias of Q1 increases/decreases (which one). Q35. In view B of figure 4-39, when the load current increases and the output voltage momentarily drops, the resistance of Q1 increase/decreases (which one) to compensate. Current Regulators You should now know how voltage regulators work to provide constant output voltages. In some circuits it may be necessary to regulate the current output. The circuitry which provides a constant current output is called a constant current regulator or just CURRENT REGULATOR. The schematic shown in figure 4-40 is a simplified schematic for a current regulator. The variable resistor shown on the schematic is used to illustrate the concept of current regulation. You should know from your study of voltage regulators that a variable resistor does not respond quickly enough to compensate for the changes. Notice that an ammeter has been included in this circuit to indicate that the circuit shown is that of a current regulator. When the circuit functions properly, the current reading of the ammeter remains constant. In this case the variable resistor (RV) compensates for changes in the load or dc input voltage. Adequate current regulation results in the loss of voltage regulation. Studying the schematic shown, you should recall that any increase in load resistance causes a drop in current. To maintain a constant current flow, the resistance of RV must be reduced whenever the load resistance increases. This causes the total resistance to remain constant. An increase in the input voltage must be compensated for by an increase in the resistance of RV, thereby maintaining a constant current flow. The operation of a current regulator is similar to that of a voltage regulator. The basic difference is that one regulates current and the other regulates voltage. Figure 4-40.—Current regulator (simplified). Since use of a variable resistor is not a practical way to control current fluctuation or variation, a transistor and a Zener diode, together with necessary resistors, are used. Recall that the Zener diode provides a constant reference voltage. The schematic shown in figure 4-41 is that of a current regulator circuit. Except for the addition of R1, the circuit shown in the figure is similar to that of a series voltage regulator. The resistor is connected in series with the load and senses any current changes in the load. Notice the voltage drop across R1 and the negative voltage polarity applied to the emitter of Q1. The


Electrical News
Transactors -- Expanding the Role of FPGA-Based Prototypes
FPGA-based prototypes offer unbeatable flexibility, capacity, and speed. Extending their...
eetimes.com
Awesome 3D Electronic Sculptures
These little beauties are created using thousands of discrete components...
eetimes.com
Graphene Polymer Speeds Electron Transport
Depositing conducting polymers on graphene gives then highly desirable electrical...
eetimes.com
Vision Explosion Requires Mobile Architecture Rethink
CEVA's Eran Briman examines the explosion in vision processing and...
eetimes.com
ECC Brings Reliability and Power Efficiency to Mobile Devices
Error correcting code increases memory density and bandwidth while maintaining...
eetimes.com
Friday Quiz: Spectrum and Network Measurements
Wireless is everywhere, but not without spectral measurements....
eetimes.com
LTE-U for Small Cells Improves Wi-Fi Environment
In LTE-U, LTE technology over an unlicensed band is paired...
eetimes.com
Web Giants Dictate Road Maps
Big data centers such as Amazon, Google and Facebook are...
eetimes.com
IoT Terrain Still Shifting
The Internet of Things continues to fragment with competing networks...
eetimes.com
Infineon: CAN FD Success Goes at Expense of FlexRay
The faster version of the venerable CAN bus, CAN FD...
eetimes.com
Maker Faire Sydney – Trends in Hardware Innovation Fireside Chat
2014 Sydney Maker Faire Power House Museum 17/8/2014 Trends in...
eevblog.com
Apple's March 9 Event: Is It Time For The Apple Watch?
Apple fans and non-fans alike are waiting to "watch" what...
eetimes.com
Tessera Buys Smart Sensors for Iris Recognition
FotoNation Limited, a wholly owned subsidiary of chip packaging company...
eetimes.com
Hi-Speed Transistors from Liquid Processing
A University of Chicago lab has invented a new kind...
eetimes.com
An Appetizing Archive of Propitious & Pragmatic Resources
EE Times blogger Adam Taylor has created a website containing...
eetimes.com
ESC Boston 2015 Sneak Peek -- Open Source Electromagnetic Trackers
Here's a sneak peek at one of the presentations to...
eetimes.com
Radars Can't Spot Mysterious Drones over Paris
Unidentified drones were spotted in the skies above Paris two...
eetimes.com
18 Views of ISSCC
Engineers showed advances in lower power, higher performance and media-rich...
eetimes.com
IoT Starter Kit Connects Developer to Cloud in Moments
Seeking to simplify the prospect of creating an IoT prototype...
eetimes.com
 


Privacy Statement - Copyright Information. - Contact Us

comments powered by Disqus

Integrated Publishing, Inc.
9438 US Hwy 19N #311 Port Richey, FL 34668

Phone For Parts Inquiries: (727) 755-3260
Google +