Posts: 223
Joined: Fri Oct 27, 2017 11:14 pm

Very small relay?

Sun Dec 09, 2018 5:24 pm

Hi there.

I need to control a bunch of fans from a pi, too many to control from the 5v pin. So I thought I'd use either a 5v or 3v pin to trip a relay which would open a 5v or 12v (fans undecided at present) line to power them.

The relays would have to be pretty small and surface mount for proto board.

Could a kind person please recommend a couple of options?

Many thanks.

Posts: 769
Joined: Wed Jul 25, 2018 9:29 pm
Location: Netherlands

Re: Very small relay?

Sun Dec 09, 2018 5:50 pm

Is there a specific reason for you not to use a (NPN) transistor or a (n channel) MOSFET? Those components are smaller that a relais. And if you need the isolation layer. You could also use a optocoupler.

You could also use a PMW (computer) fan. Then you can control the fan speed. And if it need to be "on" or off.

To give you some ideas of a small relay. You can't connect those relais directly to the GPIO, they will destroy that pin. Because the relais coil need to much current:

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