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Electronic Speed Control

Bob Harbour

This document describes an electronic speed control designed to drive two DC motors from a 7.2 Volt battery pack to be controlled by a commercial multi channel model radio control system. Conceived for a tank-like vehicle, one motor drives the left side wheels or tracks and the other motor drives the right side. As it is shown here, there is a left-right steering input and a forward-backward throttle input, like would be used on a model car radio unit. It is designed using analog circuits rather than a micro-controller or FPGA to allow construction with ordinary breadboarding techniques and no specialized device pro-grammers. It will require a good voltmeter and an oscilloscope to perform the initial checkout and calibration. After designing and testing this project, it became pretty obvious that discrete analog is a painful way to do this due to the high parts count and the some-what involved setup and calibration procedure, but there is still value in having a controller that can be built with no exotic equipment. An additional feature of this design is that it can be built in several configurations due to the modularity of the design. It has been con-figured with separate right and left throttle controls like a bulldozer, and it has been set up with direct wired controls instead of the radio link. Note: This is a work in progress and is evolving as work is done on this project.

[Editors Note: I would really like to thank Bob for this submission. The only format this document was available in is a .PDF file, which is linked to below. It is worth downloading and reading!]

To read the rest of this article, please follow this link: spctl3.pdf (approx 500kb of good stuff!).