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Voltage: Parallel and Series Circuits (2019)
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1. Introduction: LED Sign -
2. Failed Series Circuit
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Check Your Understanding: Failed Series Circuit -
Mini-Project: Voltage Investigation
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3. Parallel Circuits
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Upload a photo of a parallel circuit used to power multiple independent loads. -
Mini-Project - Shared Voltage Nodes
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Check Your Understanding: Shared Voltage Nodes
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Wire Coloring
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Check Your Understanding: Parallel Circuits
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4. Power Panels - Managing Parallel Circuits
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Mini-Project: Mounting to the Terminal Block
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Mini-Project - Terminal Block with Jumper
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Check Your Understanding: Power Panels
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Unit Project: LED Sign
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Upload Photo: LED Sign
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Upload Block Diagram: LED Sign
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Parallel Circuits
Mini Challenge Parallel Circuits
Having two "loads" (LEDs, motors, etc.) on the same "line" (electrical path) forces them to share voltage, which raises the amount of voltage required, and can complicate troubleshooting.
Did You Know? When a light bulb or LED burns out, it no longer conducts electricity through it (it becomes an "open"). If one of the lights in a series circuit burns out, it breaks the electrical path they all share and prevents any of them from lighting up. This makes it very difficult to determine which part needs to be replaced. Old strings of Christmas lights were wired in series and were famously difficult to troubleshoot for this reason!
Christmas Lights
Instead, try building a circuit with multiple paths instead, one for each LED.
Parallel LED Circuit
Parallel Circuit Diagram
Use the multimeter in voltage mode to check the voltage "across" each of the LEDs. What voltage difference do you expect to see? Is that what you actually see? Take a picture of you testing your circuit to upload later.
Explanation
A battery can send electricity down multiple paths at the same time. This lets us construct a circuit with only one LED along each path. Each path has a full 3.3V of electrical potential to work with, so both LEDs are able to light! Having both LEDs on will draw more power from the battery and cause it to drain faster.
Try It: Separated or not?
The two "mini-circuits" are not fully separate.
Try replacing one of them with a paperclip or wire that simply connects both terminals of the battery.
What happens to the other LED?