Align governor sensor adaptor mount for TSA 700E helicopter

thingiverse

This is a mount for the Align magnetic governor sensor used by the TSA Infusion 700e helicopter. It provides provision for a governor sensor using magnets on the auto rotation gear, but existing mounting holes on the frame are designed for a TSA sensor no longer available, so this mount was created for an Align sensor. The mount attaches to unused holes for the rudder lead retaining clip on the side opposite where the rudder servo is typically mounted. When using the Align sensor, you must swap the red and black wires in the plug because red is ground and black is positive. Additionally, do not use the 4x1.5mm magnets that come with the sensor as they are too weak to trigger it from its mounted position (about 2mm of separation between the sensor and the magnet). Instead, obtain some 4x2mm neodymium magnets from eBay or a similar source (the sockets for the magnets are 2mm deep). "Instant" CA glue sets too quickly to install the magnets, which fit closely and may become glued in place before fully seated. I used JB weld for this purpose, also finding it necessary to use a press due to trapped air under the magnets. A small hobby vice would also be effective for this task. Apply just enough pressure to seat the magnets (they will make an audible "pop" as the air is pushed out around the magnet). Do not test fit the magnets before gluing, as they are nearly impossible to remove once installed. I recommend installing both magnets facing the direction that triggers the sensor rather than opposite directions, typical for clutch bell magnets. This is because you would only receive one pulse per revolution of the head with a single magnet. By facing both magnets towards the sensor trigger, you double the resolution of the RPM signal. The number of pulses per revolution should be set to the actual number of magnets that trigger the sensor (two if you've installed both to trigger the sensor) rather than divided by two as you would with a brushless motor sensor and the gear ratio should be set to 1:1. To attach the sensor to the mount, you will need two M2x6mm machine screws and an M3x8mm screw to attach the mount to the frame. I found that self-tapping M2.5 screws were slightly too large for the holes in the sensor, so I used machine screws instead. For the M3 screw, a self-tapping screw worked well, though a machine screw could also be used (be careful not to overtighten machine screws in plastic). The sensor mount must seat fully against the side of the frame. If the post is too large, you may need to resize it slightly. I found that if it's only slightly oversized near the bottom, you can press the mount into an M3 screw hole in a piece of CF with a vice or arbor press to correct it.