A GPIO pin opening/closing a high power circuit?

Question

sorry if this a very beginner question but I'm still quite new to the field of electronics generally.

I have a requirement to connect a Raspberry Pi to an existing electronic lock, and hopefully use a signal from one of the GPIO pins to cause the lock to unlock. I've been advised that the electronic lock is a 1A circuit, at (I think) 12V, and that any time the circuit is closed, the lock is triggered. Meanwhile, the RPi operates at 3.3V, with a 2-20mA output per pin and a 50mA limit.

Given this, what solutions do I have for allowing a logic signal from the RPi to control the much higher-power lock circuit? Initial research seems to suggest simply a transistor or relay of some sort would suffice, but my attempts to understand how I'd wire these together have been spectacularly unsuccessful. All my programming for the RPi is fine, I can drive the pin (or several pins if needed) high or low at the appropriate time - I just can't figure out how to let it control a 1A circuit. Do I need a full circuit of some sort that connects to both, or is there a way to just use a single component here?

Answer 1

This would be one simple solution. Note that the relay contacts should be rated for 2 or 3 times the load current so the contacts will last a long time.

If you use a logic-level MOSFET to drive the load directly be sure the MOSFET is rated for several times the load current and has a heatsink if it gets hot to the touch. Also a snubber or 'flywheel' diode is mandatory.

^{simulate this circuit – Schematic created using CircuitLab}

Answer 2

At 1 A level, I think relay will be overkill. I think FET will be good for this application and will be cheaper solution. Replace lamp with your lock in this circuit.

(Image source: "An example of using the MOSFET as a switch" at Electronics Tutorials)