Heatsink in Capacitance Multiplier?

[roger-k]

I'm making an amplifier: JLh 2x10W.
The output transistors is MJ15003.
I will also use the same transistors in the Capacitance Multiplier powersupply.

So my question is:
Do the transistors in the Capacitance Multiplier produce the same heat as the output transistors? (The bias is about 3A)

Will it be bad to have these transistors at the same heatsink as the output transistors? Or is it enough with a much smaler heatsink?

[richie00boy]

The capacitance multiplier should not make as much heat. I would use a separate heatsink as then you don't have two different thermal systems on the same block, also you could be making the cap mult transistors hotter than they need to be.

[janneman]

They will dissipate the product of current and voltage. P=I*V. Capacitance multipliers normally have only a few volts across them. So, at, say 3V across the series transistor, at 3A, P=9W. For the output transistors that is the supply voltage * bias. What's the supply, some 24V? That will be 24 * 3 = 72W.
Putting the cap multiplier series transistor on the same heatsink as the output transistors is probably a good strategy.

Jan Didden

[roger-k]

Thanks for the answers.

Yes it is maybe a good strategy tu put the cap multiplier series transistor on the same heatsink as the output transistors.
But as richie00boy tells maybe the mult transistors are getting hotter than they need to be.....??

Any who have some experience with this?