# Voltage Regulator Projects

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Many electronic circuits put forth erratic voltages; those working with circuits need to control this phenomenon. Voltage regulation plays an integral role in any electronic or electrical circuit. Employ the tried-and-true technology of many solid-state devices to regulate voltage; experimenting with various circuits will allow you to stabilize an erratic voltage output. Always use caution when calculating circuit values, and with electricity in general. If you feel you need assistance to build any circuit, talk to a qualified electronics technician.

## Zener Diodes

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A Zener diode lies at the heart of every voltage regulator circuit. A regular diode allows current flow only in one direction, similar to a one-way valve in a pipe carrying water. A Zener diode, has a unique property, however: When the voltage level reaches a certain point, it "breaks over" and allows current flow in both directions. It acts much like a one-way valve with a spring that opens all the way when the water pressure in the pipe rises to a certain level—a predefined break-over point called the breakdown voltage. For example, a 12-volt Zener will break down at 12 volts, preventing the output of the circuit from exceeding 12 volts. Since the diode itself does not break, it will last for years.

## Shunt Regulation

Professor M. H. Miller at the University of Michigan designed an experiment demonstrating shunt regulation. The circuit is extremely simple, and a common one in electronic circuits. Miller placed a Zener diode across the power lines and extracted the regulated voltage from the terminals of the Zener. The phenomenon is known as "shunt regulation" because the regulator is in parallel, or connected across, the final load circuit. You can duplicate this circuit from off-the-shelf-parts; do not exceed the wattage rating of the Zener, however. Size up the current-limiting resistor accordingly; if you exceed the wattage rating, the diode itself will "fry" or maybe even explode. To build the circuit, first reduce the voltage with a current-limiting resistor connected to one terminal of a transformer. Place a Zener diode between the output terminal of the resistor and one terminal of the transformer. Extract the regulated electricity from the terminals of the Zener diode.

## CMOS Regulation

Copper metal oxide semiconductors (CMOS) integrated circuit chips have built-in Zener diodes and current rectifying circuitry as well. Tufts University experimenter Vincent Lixiang Bu presented and reported on a circuit that uses CMOS technology. The circuit incorporates a CMOS integrated circuit chip along with a power transistor controlled by the chip. This circuit is also easy to duplicate, using readily available components from any electronics supplier. It incorporates a load resistor, a Zener diode and a power transistor all in one chip. Simply connect the two output terminals of a transformer to the input terminals of the regulator. Extract the regulated electricity from the two output terminals of the regulator.

## Auto Regulator

You can use a car voltage regulator for different applications. For example, a windmill puts out erratic voltage levels. You can feed the a windmill's output into a car regulator to hold the output voltage under 12 to 14 volts—a handy feature if you use the windmill to charge up a battery bank. Nathan Eagle and Benjamin Olding at the Massachusetts Institute of Technology used a car alternator, which has a built-in regulator, to charge a battery. The researchers hooked up the regulator the same way as it would normally be in a car. They connected the generator's two output terminals to a car regulator's two input terminals, then hooked up the two output terminals of the regulator to a battery bank. They used a load-limiting resistor between the alternator and the regulator to limit current.