I am looking for a set of radios to monitor my IIS (Ignition Interlock System) when I am warming up my car on cold mornings. Some people use a baby monitor but the problem I am finding on most setups is that the parent unit is battery operated but the baby unit is AC powered. What I am specifically wanting is to have the radio/walkie talkie that is in the car placed near the IIS to be “always listening” so I know when the re-test begins and starts the 5 min. countdown. Does anyone know of any low-cost (around $20-$30) radios (preferably on Amazon) that let me set one of the units to always listen like a baby monitor without having to push the talk button to monitor sound? I have considered forcing the button to stay pushed in with glue or wrapping something around it but if it becomes un-pushed or malfunctions and I don’t hear it, I will get a violation.
Any leads would be greatly appreciated!