Below a look and an integrated system I developed. I’m holding a front alternator bracket. Threaded into the bracket is a very high quality sensor for a tach. It is tripped by two small AN-3 bolts, in precision CNC drilled holes in the ring gear. This is a compact arrangement using parts like the bracket and ring gear which are already doing a primary task. This gives 2 pulses per revolution, compatible with virtually all glass cockpits.
The sending unit is not cheap. It is made in the US by a very reputable company. I have it on my website as a service, the price I sell them for is $2 over what it costs me to buy them hand have them shipped to my place. But I like the way it works with the other parts to be a very simple and elegant installation. If you got a ring gear from me in the last few months, it came with the 3/16″ holes, alternator brackets have the 3/8-24 thread for the sensor. If you have earlier brackets or ring gear, you can drill these holes carefully in your shop. I’ll include the locations in a later video.
Several months ago I shared a look at testing eight different pickups and various locations on the ring gear. The is the final result for anyone building a plane with a glass cockpit.