Question T6A12
From subelement T6 - T6A
What type of switch is represented by component 3 in figure T-2?
Why is this correct?
A Single-pole single-throw (SPST) switch is a basic on/off switch that controls one circuit (single pole) and has two positions (single throw) - open or closed. This is the simplest switch type, like a light switch that either completes or breaks one circuit path. The other options are wrong because: Single-pole double-throw (SPDT) switches between two circuits, while double-pole switches control two separate circuits simultaneously.
Memory tip
Remember switch terminology using the railroad analogy: poles are input tracks (circuits controlled), throws are destination tracks (positions available). SPST = one input, two states. This naming pattern applies universally to all switch types in electronics.
Learn more
In practical amateur radio operations, SPST switches serve as power switches for equipment, antenna disconnect switches for safety during maintenance, and simple feature toggles. Understanding switch specifications becomes crucial when selecting components for homebrew projects or troubleshooting station equipment. The switch's current and voltage ratings must match your application's requirements, and contact arrangement determines functionality in your circuit design.
Think about it
Why do you think component 3 would be positioned in a power supply circuit diagram, and what would happen to the circuit's operation if this switch were left open?