How about "metal, clamped, and use lock washers."
More seriously, anything you can do to provide airflow is good.  Of
course you have to keep the grass clippings from collecting on the
TO220s.  If your motor has a fan and you can duct the intake over the
transistors it will help cooling a lot.

Sherpa Doug

> -----Original Message-----
> From: Byron A Jeff [mailto:byron@CC.GATECH.EDU]
> Sent: Tuesday, August 28, 2001 9:17 AM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: [OT]: How to heatsink a lot of power electronics?
>
>
> After years of development ;-) I've finally have my prototype
> robotic lawnmower
> platform to a usable state. The most valuable lesson I learned is that
> everything in the drive path must be metal, clamped, and use
> lock washers.
>
> Next on the agenda is motor control for the drive motors. Bob Blick's
> discrete h-bridge is a natural for the project. But of course
> you end up
> with 8 power transistors, plus another one for the cutting motor.
>
> I wanted to get some ideas of the best way to heatsink a
> bunch of power
> transistors.
>
> TIA
>
> BAJ
>
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