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Transistors as switches

news.ycombinator.com

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Transistors as switches

#1
how do transistors work as switches? i understand how it uses a small current to change the conductivity properties, and thus to control a larger current; i dont understand how the smaller current is controlled in the first place.

Re: Transistors as switches

#2
They have a base, a collector and an emitter. The low current from the base makes the atoms between the collector and the emitter to allow the electric current to pass. However it may be easier and more safe to use optocoupler if using low amperage and a relay for high amperage.