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
Carmakers Raise Stakes in Map Battle vs. Google
BMW, Audi and Mercedes -- to purchase Nokia's HERE map...
NI Week: Videos From Opening Day
NI Week opened today with a two-hour exhibit opening. Here's...
What Will Make Wearable Technology Take Off?
Wearable technology will take off when people can wear it,...
Expansion of Information Technology Agreement Big Deal for Semiconductor Industry
The recent ITA deal is a huge shot in the...
OmniVision Shareholders Approve Seagull Takeover
The shareholders of CMOS image sensor vendor OmniVision Technologies Inc....
Indian Fab Project Hires Former GloFo Exec
Indian foundry fab will be located near Indore in Madhya...
NASA Preps Venus ICs
NASA is sending a mission to Venus, where the surface...
Will The World Coalesce Around USB Type C?
USB Type C is still too new for any market...
Agile Design for Hardware, Part III
In the final installment of a three-part series, two Berkeley...
EMI Antennas Come in Many Shapes & Sizes
EMI antennas are needed for compliance and precompliance emissions and...
The ACM/IEEE International Conference on Information Processing in Sensor Networks...
Silicon Valley's Longest-Serving CEO Beginning New Chapter
With the impending close of Microchip's $840 million acquisition of...
EEVblog #774 – Low Battery Discharge Testing Part 1
Dave shows how to do discharge testing on AAA and...
Perambulating & Texting -- Dazed & Confused
It seems that walking while texting is becoming endemic; so...
IBM Takes A Second Turn at PCM Drift
Another approach taken by IBM and Macronix to address phase...
The Next Big Thing Is The Continuum
What will come next for us? Internet of Everything, wearables,...
Making EDA Exciting Again
There are still plenty of exciting challenges out there for...
Turing Test -- Are You Talking to a Human or a Machine?
Imagine you are allowed to pose five questions to determine...
MediaTek Cautions 'Weak Demand' for Handsets
MediaTek has pared its expectations for 2015 as a result...
Patent Search Supports View 3D XPoint Based on Phase-Change
Is 3D XPoint non-volatile memory really just a version of...

Privacy Statement - Copyright Information. - Contact Us

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

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