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
Backlash Coming on Car-to-Car Talk?
Vehicle-to-vehicle communications will be mandated in the US, but public...
eetimes.com
Training Opportunities Abound at ARM TechCon
ARM TechCon is only a few weeks away, and if...
eetimes.com
10 Top Video Parodies on User Interfaces
There have been some interesting videos of "user interface parodies"...
eetimes.com
Making Wearables Personal
Wearables should be as unique as the person who wears...
blog.designersofthings.com
Infographic: A History of Wearable Tech
Take a stroll down wearable memory lane in this great...
blog.designersofthings.com
18 Views of the Silicon Horizon
Semiconductors are poised for high single-digit growth this year and...
eetimes.com
Power Week: Did We Just Avoid an 'Electric Armageddon?'
While a powerful solar storm this past week resulted only...
eetimes.com
Rube Goldberg Rocket Launch
For their first real-world project, a group of budding young...
eetimes.com
Makers, Engineers Mix at NY Event
Educators and engineers from across the country attended New York's...
eetimes.com
Interview with Rod Elliott from Elliott Sound Products
Meet Rod Elliott the man behind the famous sound.westhost.com audio...
eevblog.com
Boeing, SpaceX Take US Back to Space Station
NASA taps Boeing Co., the safe but expensive choice, and...
eetimes.com
Technology You Can Sink Your Teeth Into
Thanks to 3D imaging software and a special milling machine,...
eetimes.com
Does Reducing Power Consumption Actually Save Energy?
It's the law of unintended consequences again, as regulations to...
eetimes.com
Local Motors Succeeds in Test Driving First 3D-Printed Car
3D-printed car has successful test drive!...
eetimes.com
Designer of Things Keynote Speaker: Gadi Amit
EETimes is pleased to announce that Gadi Amit will be...
eetimes.com
Sensor Hubs Aided by IEEE-2700-2014 Datasheets
The first MEMS standard, the IEEE 2700-2014, will standardize data...
eetimes.com
Dr. Duino Diagnostic Shield Deduces Dilemmas in Arduino Shield Stacks
When sandwiched an Arduino Uno and a shield -- or...
eetimes.com
Asia-Pacific IC Usage Domination Growing
Asia-Pacific is the dominant market for ICs for most products...
eetimes.com
Open-Source Hardware Circa 1920
An engineer discovers amazing schematics and documentation pasted to the...
eetimes.com
Intel Core M vs. Pentium M
A comparison of the Intel's recent Core M to its...
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 +