For TO-220 transistors used as drivers, not in the PS or for other duties.
Is there an ideal operating temperature range? At what point would you choose to add a heat sink?
Can running either too cool, or too warm, compromise performance in any way?
Is there an ideal operating temperature range? At what point would you choose to add a heat sink?
Can running either too cool, or too warm, compromise performance in any way?
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MJE15032 data saz 25C ambient + 2W/(0.016W/degC) = 150C, the maximum storage temp. And the Tc=25C max is 50W and 0.4W/degC so the case to ambient thermal resistance is 62.5deg/W - 2.5deg/W = 60deg/W. So the case temp will be 25 + 60p. For 1 watt that would be 85C. But a hot driver is a thermal stability liability, so unless they run cooler than the main outputs, you need to heatsink them.
If the schematic is sensible at Hfe than the schematic is bad.
For a good schematic, this variation of Hfe with the temperature it doesn't matter.
For a good schematic, this variation of Hfe with the temperature it doesn't matter.
Even driving one pair class AB output transistors at 60 w/ch, good reputation brands put a heatsink on the drivers. This is diyaudio, coming in $1 less than the competition is not a goal. The labor to install a heat sink in a factory is a lot of the price, and our diy labor is free. Spend $1/driver for purchased heatsinks, or do as I have done, saw off 1.5 cm of aluminum screen channel and drill some holes in it. it is the edge of a metal body that transfers heat to the air, and holes or slots filed in an aluminum edge increase the length of edge. I use #4 or #6 machine screws and elastic stop nuts so the nuts don't come loose.
Extreme cold can break internal bond wires in semiconductors. A metal case (TO3, TO5, TO39) shrinks at a different rate than the silicon die. Operate consumer electronics above freezing where possible.
