phoenixsilverbird wrote:After a lot more research, it turns out that some relays are simply configured for AC and some aren't.
I have no idea why the DC ones are only available from china and the USA though.
I'm awaiting a response concerning the ampere input for the relay.
All the relay coils will work on AC or DC, however there are issues with heat and the metal core.
AC types generate a 'reversing flux' which is great for cooking, DC types are normally solid and don't like AC keep switching them around.
If you have an operating voltage and a meter to measure ohms then Ohm's Law will help. Also the inrush current is about 8 times the running current.
Looking at your original choice of solenoid...
Driving it with DC seems to be best, for only a second or so. It says it is 1 amp.
You need a power supply to operate it that can deliver just over 1 amp, and even add a capacitor to help with the 'inrush' requirements.
The Pi can drive an optoisolator that will power a transistor etc etc.
Now with electric gates you sometimes get a CLOSE command to OPEN them first, WHY?
The locking bolt is mechanically restrained by the force of the gates, and a 0.5 second CLOSE command then an OPEN command "jerks" the gates to help the locking bolt retract cleanly.
Your locking bolt may require a few seconds of energy to overcome the mechanical force applied by the door. IE: what works smoothly on the test bed, may snag in situ.