These BD135/136, 137/138 and 139/140 are all "the same thing", binned for voltage and Hfe rating.
http://www.fairchildsemi.com/ds/BD/BD135.pdf
These are 12'5W total dissipation parts (if properly heatsinked).
The 1'25W collector dissipation number is (in my understanding) valid for the 25°C ambient temperature, and "naked" transistor. IOW, a transistor without any heatsink in a place that doesn't exceed 25C.
I don't recommend running these DOAs without a heatsink.
some ideas here:
http://parts.digikey.ca/1/3/to-126-heatsink
While this is entirely non-scientific, I'd recommend choosing the heatsink "with a thermometer". IOW, don't let the output pair run hotter than cca. 40°C at full output into your chosen real-life load (if possible).
These DOAs are somewhat "pure" designs, so they don't incorporate any current-limiting (except base-current-starving) nor temperature stabilizing mechanisms, so the output transistor pair must be just simply heatsinked.
http://www.fairchildsemi.com/ds/BD/BD135.pdf
These are 12'5W total dissipation parts (if properly heatsinked).
The 1'25W collector dissipation number is (in my understanding) valid for the 25°C ambient temperature, and "naked" transistor. IOW, a transistor without any heatsink in a place that doesn't exceed 25C.
I don't recommend running these DOAs without a heatsink.
some ideas here:
http://parts.digikey.ca/1/3/to-126-heatsink
While this is entirely non-scientific, I'd recommend choosing the heatsink "with a thermometer". IOW, don't let the output pair run hotter than cca. 40°C at full output into your chosen real-life load (if possible).
These DOAs are somewhat "pure" designs, so they don't incorporate any current-limiting (except base-current-starving) nor temperature stabilizing mechanisms, so the output transistor pair must be just simply heatsinked.