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Old 3rd February 2009, 05:43 PM   #11
lineup is offline lineup  Sweden
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No problems.
Like told.
Any variant BD140 will do well

When you use one aluminum piece heatsink per transistor, there can be no shortcut.
Even if using no TO-126 transistor insulators.
Just do not let those heatsinks come into electrical contact.

If you use eletrical insulators for mount transistors, then is no issue.
Can not be shortcuts whatever.
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Old 3rd February 2009, 06:05 PM   #12
mjf is offline mjf  Austria
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hello.
yes,you can use bd140 ,.............;
I think the heatsinks are too small,they will run hot.be carefull when you power up..........
greetings..............
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Old 3rd February 2009, 07:32 PM   #13
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Quote:
Originally posted by lineup
No problems.
Like told.
Any variant BD140 will do well

When you use one aluminum piece heatsink per transistor, there can be no shortcut.
Even if using no TO-126 transistor insulators.
Just do not let those heatsinks come into electrical contact.

If you use eletrical insulators for mount transistors, then is no issue.
Can not be shortcuts whatever.

Quote:
Originally posted by mjf
hello.
yes,you can use bd140 ,.............;
I think the heatsinks are too small,they will run hot.be carefull when you power up..........
greetings..............

Thanks guys

Crikey those transistors must get hot! Nuuk's used quite a lot of metal on his heat sinks. There must be about 9mm attached to the back of those transistors, and that's not including the bracket to both sides.

Richard
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Old 6th February 2009, 09:04 AM   #14
AndrewT is online now AndrewT  Scotland
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Quote:
Originally posted by Tripmaster
Crikey those transistors must get hot!
Hi,
measure the voltage drop across the pass transistor.
Measure the current through the pass transistor.
Multiply Volts * Amps to arrive at Watts. Choose a heatsink to suit.
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Old 6th February 2009, 03:33 PM   #15
Nuuk is offline Nuuk  United Kingdom
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Quote:
Crikey those transistors must get hot! Nuuk's used quite a lot of metal on his heat sinks. There must be about 9mm attached to the back of those transistors, and that's not including the bracket to both sides.
No they don't get hot at all. But Pedja told me to heatsink them and that's what I made up from scraps of aluminium lying around the bench.
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Old 6th February 2009, 07:55 PM   #16
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Quote:
Originally posted by Nuuk


No they don't get hot at all. But Pedja told me to heatsink them and that's what I made up from scraps of aluminium lying around the bench.
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Old 6th February 2009, 07:57 PM   #17
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Quote:
Originally posted by AndrewT
Hi,
measure the voltage drop across the pass transistor.
Measure the current through the pass transistor.
Multiply Volts * Amps to arrive at Watts. Choose a heatsink to suit.

Thanks Andrew

I will do what you suggest just so I understand. I'm sure Nick's are just fine or he would have changed them.

Richard
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Old 6th February 2009, 07:59 PM   #18
Nuuk is offline Nuuk  United Kingdom
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Friends in high places
Yes, he lives in a loft apartment!
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Old 6th February 2009, 08:04 PM   #19
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Originally posted by Nuuk


Yes, he lives in a loft apartment!

He must be popular with his neighbours!
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Old 8th February 2009, 06:17 AM   #20
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Hi Andrew

What is the formula to calculate the LM3886 power output? I will be using 2x300va transformers with 25v secondaires. Pedja's discrete PS has a dc output of about 26-27v. I am wondering if there will be enough power to drive my 8ohm 88db speakers.

I currently using an unregulated snubberized power supply, this is more than adequate.

Thanks again

Richard
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