ScytekMS-2 Dual Zone Dual-Adjust Microwave Motion Radar Sensor

doesn't work, it won't adjust

Update 20141118: This unit never did work. It now simply oscillates at the outputs no matter what the settings are.I was sold this along with a Scytek A10 automotive alarm system (not by this vendor!), with which it is NOT plug-compatible. The outputs are active LOW, shorted to GND by open collectors of 2N3406 NPN transistors. The EXT trigger out green LED is always on, and on activation, gets brighter. That means the output on the Ext trigger never goes higher than 3.5V with a 1K load resistance, which may constitute a constant activation with a +12V security system. You could use the INT trigger output, which allows the unactivated output to pull all the way up to +12V, but it is not nearly as sensitive to motion as the EXT trigger.In my limited pre-installation testing, the unit has never falsed, even with the gain on the EXT trigger all the way up. If the gain on the INT channel is turned too high, the unit oscillates at the output with a period of a few seconds. I think that is why the limited instructions say to adjust the EXT gain first.This unit can be used in a home security system as well, but not easily. The housing size (even the bare circuit board) is too wide to fit a single receptacle box; the mounting ears are not similarly dimensioned; the sensitivity is designed for a car, not a home; and care must be taken with wiring the zone loop terminator resistor so the output activation shorts it out (The MS-2 outputs are not isolated relay contacts).