How to Build a Rectifier

Capacitors remove ripple from the output voltage of rectifier circuits.

Rectifiers convert alternating current to direct current. These circuits primarily comprise diodes and a capacitor, but they may also use a voltage regulator to trim the output to the desired DC voltage.



There are four primary types of rectifiers: half wave, full wave, bridge, and full-wave bridge. Each has specific advantages and disadvantages. The rectifier described here is a diode bridge type that uses a zener diode to limit the output voltage to six volts, and capacitors to smooth the output to nearly perfect DC voltage.

Things You'll Need

• Small electronic project breadboard
• Long-nose pliers
• 22-gauge jumper wires
• 1N4007 silicone diodes, 4
• 470 uF 50-volt electrolytic capacitor
• 1N816 zener diode
• .01 uF 16-volt ceramic disk capacitor
• AC transformer (120 volts in, 9 volts out)
• Multimeter
• Wire strippers (optional)

Instructions

1. Use the long-nose pliers to bend a right angle into each leg of all four diodes, so that you can insert the diodes vertically between two vertical rows of the breadboard.

   Insert the diodes onto the breadboard so that each diode's cathode (the end with the line on it) aligns with the anode of the next diode.

2. Insert jumper wires to connect the diodes to each other. Connect the anode of diode 1 to the anode of diode 3. Connect the cathode of diode 1 to the anode of diode 2. Connect the cathode of diode 3 to the anode of diode 4. Connect the cathode of diode 2 to the cathode of diode 4. Connecting the diodes in this way creates a bridge rectifier.

3. Insert jumper wires to connect the AC transformer's output to the circuit. Connect one transformer output to the anode of diode 2. Connect the other transformer output to the anode of diode 4. If a center tap is present, do not use it.

4. Insert jumper wires to connect the diode bridge rectifier to the top and bottom breadboard power block positions, which you will use as the diode bridge rectifier outputs. Connect the anode of diode 1 to the set of holes along the top of the breadboard for the positive output, and the cathode of diode 2 to the bottom set of holes for the negative output.

5. Insert the electrolytic capacitor's positive terminal into the positive bridge output and its negative terminal into the negative bridge output. Insert the zener diode's anode into the positive bridge output and its cathode into the negative bridge output. Insert one leg of the ceramic disk capacitor into each bridge output.

6. Check the output with the multimeter. Set the multimeter to read DC volts. Connect the red probe to the positive bridge output and the black probe to the negative bridge output. Turn the circuit on; the multimeter should read about six volts.

Tips & Warnings

• Understand the breadboard. The vertical columns of holes are grouped five to a column. The five holes are electrically connected. Inserting a wire, a diode lead and a capacitor lead into three of the holes in a group of five connects all three components. Each group of five is separated from the other groups of five. The top and bottom blocks have two rows each which are all connected, making them ideal for use as power output or input sections.

• You can buy 22-gauge jumper wires for breadboard projects or make your own from 22-gauge solid wire. Simply cut the wire to the length you need, and use wire strippers to strip a quarter-inch of insulation from the ends.

• The transformer should have a cord and a case that does not expose the user to 120 volts of current. Only the output terminals that carry 9 volts AC should be available. Use care not to short the output terminals when the unit is turned on.

References

• All About Circuits: Rectifier Circuits: Diodes and Rectifiers
• The Electronic Club: Breadboard

Resources

• Read this Article in Spanish