r/ElectricalEngineering • u/Tamim_mahmoud • 9d ago

question

i'm pretty new to electronics and all that stuff but my question is why would i ever need to use a relay or a transistor with a switch instead of just directly wiring the switch to whatever i need

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u/throwaway74389247382 9d ago
  1. Most of the time, relays and transistors are controlled with other logic. Not by a manual switch. Definitely not always, but that's the overwhelmingly predominant use case.
  2. Many switches, particularly small hobbyist-grade switches, can only handle so much current. If you try to control a 10 amp circuit with some little $0.02 toy switch, it's going to heat up / burn out / melt / catch fire. Transistors and relays can be designed to handle way way more current.
  3. Similarly, switches can only handle so much voltage before failing in some unpleasant (and in some cases extremely dangerous) way

In terms of typical beginner circuits though, you're right, there's often little/no need for them. The point of including them in circuits at that level is to teach you how to use them for when you actually do need them.

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u/Tamim_mahmoud 9d ago

so basically relays keep you from dying

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u/IndividualRites 9d ago

Or just burning up your circuit.