Atlas track un-couplers. Note that it adds a small hole in the center track power.
Note that this device picks track common and requires power to a momentary push button to energize the coil. Hold too long you could burn the magnetic coil. IMO I believe these are provided with the push button.
Thumb tack uncouplers. Top is an electro-coupler. The magnet pull the thumb tack down, releasing the coupler jaw which is spring loaded.
Additional note. On the Fort Pitt Hi-Railer Time saver modules there are several un-couplers, older, maybe Gargraves. Basic wiring is relatively simple as noted. It was interesting to note that these devices can draw a lot of current to operate. We eventually use a spare Z4000 track circuit to power them. At that point we could reliable open the thumb tack couplers. IMO. 
Mike CT
