Hi Olie, I am using EMX Industries CarSense 202. It’s online at a reasonable price, is self contained, can be installed parallel alongside the driveway or perpendicular under the driveway, uses a wide range for a power supply - I got several Altronix 12 volt dc power supplies with battery backup to serve multiple devices - and only 12mA of detection current with 0.25 mA standby current. I use it in a monitored zone in OP 2. It’s sensitive enough to pick up the ferrous mass of a bicycle (and a car obviously) but not a pedestrian (unless they are right on top of it with steel boots) and it does require motion to activate it - I think if you move at literally a snails pace it won’t activate. There are lots of other options out there, but this seemed to be a good fit for me.