Do we really need relay to interface with Pi's GPIO?

[lilzz]

Is relay a must have? If not , at what condition is it needed?

http://nwazet.com/nwazet-pecan-pi-relays

A relay is nothing more than a switch right?

[FLYFISH TECHNOLOGIES]

Hi,

Is relay a must have?

No.
There are just few things which are a must have,... air, water, some food and sun come to mind first.

If not , at what condition is it needed?

Typically, when you need to switch high voltage / high current load.

A relay is nothing more than a switch right?

Yes. An electronically-controlled switch.


P.S. Google can answer this kind of questions very well...


Best wishes, Ivan Zilic.

[Richard-TX]

Relays are used when a "switch" is needed. Since the Pi can only handle ttl loads that makes it a starting point. My rule of thumb is like this:

When switching main voltages a solid state relay is tops. Silent, able to be triggered by the Pi directly, plus UL/CE approved.

When switching lower voltages and/or currents a small relay works. While not silent, the noise level is acceptable.