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How to Resolve a Circuit With Two DC Power Sources

All electrical circuits contain at least two basic components -- a power supply and a load. It is possible to have multiple loads in the same circuit; likewise, it is possible to have two power sources. When two DC power sources are placed in series, the two power sources act as one larger power source. Two DC power sources placed in parallel will also act as one power source, but in some configurations, DC power sources in parallel can damage the circuit.

Things You'll Need

Electrical wire
Electrical pliers
2 lantern batteries, 6 volts
Digital multimeter
Soldering iron
Electronic solder
2 lantern bulbs

Instructions

Power Sources in Series
- 1
  Cut three pieces of electrical wire, with each wire piece 6 inches long. Strip 1/2 inch of insulating material from the ends of each wire.
- 2
  Twist one end of the first wire to the negative terminal on the first battery. Twist the other end of this wire to the positive terminal on the second battery.
- 3
  Twist one end of the second wire to the positive terminal on the first battery. Twist one end of the third wire to the negative terminal on the second battery.
- 4
  Turn on the multimeter, and set the measurement scale to "Volts DC." Attach the black multimeter probe to the third wire. Attach the red multimeter probe to the second wire. The two DC power sources, when wired in series, produce the sum of the voltage of each supply -- in this case, 12 volts DC. Disconnect the wires from the battery, and disconnect the multimeter from the wires.
Power Sources in Parallel
- 5
  Cut seven pieces of electrical wire, with each wire segment 6 inches long. Strip 1/2 inch of insulation from the ends of each wire segment.
- 6
  Place one end of the first wire on the metal bump at the bottom of the first light bulb. Melt a small drop of solder to both the wire and the metal bump. Smooth out the soldered joint with the tip of the soldering iron.
- 7
  
  The first wire must be soldered to the metal bump on the bottom of the light bulb.
  
  Solder one end of the second wire to the metal sleeve on the first light bulb. Solder the loose end of the second wire to the metal bump on the second light bulb.
- 8
  Solder one end of the third wire to the metal sleeve on the second light bulb.
- 9
  Connect the loose end of the first wire to the positive terminal on the first battery. Connect the loose end of the second wire to the negative terminal on the first battery. Note that the light bulbs will dimly illuminate. Disconnect the wires from the battery.
- 10
  Connect one end of the fourth wire to the positive terminal on the first battery. Connect one end of the fifth wire to the positive terminal on the second battery. Twist the free ends of both wires to the loose end of the first wire.
- 11
  Connect one end of the sixth wire to the negative terminal on the first battery. Connect one end of the seventh wire to the negative terminal on the second battery. Twist the free ends of both wires to the loose end of the third wire. Note that the light bulbs illuminate brightly. Disconnect the wires from the battery.

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