Power Supply C. Board -1: Proposed changes to TR712/715 for improved cooling
Oilmaster and others have proposed and alternate location for TR712/715 to gain efficiency in cooling. This seems to be a very interesting modification considering the heat generated by both these particular components and overall design. And while the option to mount these just beneath the panel meters on the horizontal flat plate would appear to be a good one, it seems a location requiring less modification may be appropriate as well. This led me to consider the primary heat sink. It seems that if you could fabricate a bracket that would attach to the existing bolts, extend horizontally, then elbow down, so that the transistor could use the external surface for both a mount and cooling, you would improve overall cooling in a manner less invasive to the original design. Upon further consideration, I decided to make a quick prototype (see pics below) to get the old
creative juices flowing. I took some scrap 1/8" aluminum, some quick measurements, and began to cut and bend. I was worried that the heatsink bolts would not be long enough to add another 1/8" created by the aluminum, but I was able to get a few turns and secure both the bracket and heatsink back to the frame. Unfortunately, 1/8" is the maximum height you can add, which leaves no room for anything isolating this bracket if desired.
CONSIDERATIONS:
This location appears to be extremely appropriate at first glance but I believe its necessary to consider the effects of heat developing from the main heatsink and its transmission to the bracket, ultimately heating the transistor. It seems obvious that the transistor rate of cooling would need to outpace the heat transmission from the main heatsink. I feel the design of the bracket, along with it's coupling to the main heatsink, can reduce or eliminate this issue entirely. An insulator of some kind inserted between the bracket and main heatsink would significantly reduce the transfer of heat. Adding additional surface area should also help the heat generated by the transistor AND heatsink for which it's mounted, cool much quicker, therefore, cutting some "fins" into the sides would seem appropriate (see hand sketches below).
Overall, I believe this is a reasonable idea but am certain it can be better, especially with the input from those monitoring this thread. I also believe it makes this thread more interesting, which is always a good thang! Please understand, I'm well aware that these modifications are not nearly as necessary as those associated with the CR2020, I'm simply enjoying the hobby and viewing this modification as a way to build skills. Hopefully this idea will peak some interest and get everyone's
creative juices flowing and the net result is something for all to use. So, please comment freely and provide as much direction and constructive advice as possible.
Prototype Pics
Hand Sketch of Proposed Changes