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DC Motor Controller for Electric Bicycle

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Step 5: Power Section construction details

These photos show how the FETs and power diodes are attached to the heat sink.  They must be kept electrically isolated from the heat sink.  The screws are covered with 1/8" heat shrink tubing and the FET and power  The heat sink that I used is re-purposed from an old broken PC power supply.
 
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dxr13ke2 years ago
Why do they need to be electrically isolated?
scd (author)  dxr13ke2 years ago
Because the case of the diode is electrically connected to its cathode and the case of the FET is electrically connected to its drain. If you don't isolate these from the electrically conducting heat sink, then you've just made a short from motor+ to motor- :)
dxr13ke scd2 years ago
One could use 2 separate heat sinks if one does not find the isolators.
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