Each sensor uses a pipe clamp, wing-nut, plastic sewing machine
bobbin and some #28 magnetic wire and cost less than $2 each.
A 10 ft. section of Cat-5 ethernet cable terminates in a
miniature audio jack in the cabin:
Each pipe clamp goes around a single MG1 or MG2 power cable with
the carriage bolt passing through the wire-wound, plastic bobbin.
The original nut is affixed and the wing nut used to lock the
This makes a simple transformer with the primary being one-turn of a
power leg and the bobbin providing the secondary and generating
the output voltage.
Earlier tests indicated a 100 turn bobbin would generate voltage in the 100 millivolt range for MG1. The MG2 bobbin has only 55 turns to keep it in the same voltage range as MG1. Experimental data using hard accelleration shows MG2 generated just under 500 millivolts. The goal is to plug the sensors into the microphone input of a Macintosh G3 Wallstreet which is rated at 2 V. max input into 6.8 k Ohms and use audio recording software to capture the data.
This example shows the detail available from an 11 minute trip.
The route was from a parking lot; up a short hill to a stretch of 55 mph;
an exit zone at 35 mph; another short hill and stretch of 65 mph; an
off ramp; a 40 mph urban street; and ended at an electronics store.
Others have already shared a lot of data about the MG1/MG2 operation but this data will help develop an automatic "Pulse and glide" system to augment the cruise control. It could also drive a couple of small speakers and give audio clues for "Pulse and glide" driving to avoid watching the energy display.