F5 power amplifier

[cviller]

Nice.
But you need to make sure to get plenty of airflow along the fins.

Or you could make a powerhouse like this:

[a.wayne]

^^^^ Is that your new BA-2 ? ................

[bear]

erpii, I think you will need to blow air if you enclose the fins like that.

For natural convection one needs to maximize the airflow, otherwise you have to derate the heatsinks by quite a bit - which means the amp will get too hot, which means the thermistors will cut back the bias, which means it won't be in full class A anymore...

...and I think one might consider putting the board into an "H" configuration... let me try ascii:

O O
| | <---heat spreader "bars"
------ <---pcb
| |
O O <--round heatsinks (not to scale)


EDIT: when I post the spaces get chucked and the drawing squishes left justified - use your imagination??

You could use 3 per line also... and the distance between the heatsinks is only because of ascii drawing...

I dunno...

_-_-bear

[udailey]

I wish I had info to share but they have not got back to me yet. However I have to agree with bear. Airflow may be necessary. I dont think it will need much though. Even a breeze will help A LOT. Computer fans are getting very very quiet. I recently got one for about 4 bucks to waft away solder fumes. Running it on a battery and a pot. I cant hear it at all even two foot from it. I would put them below pointing up. I think it would do it because I think those sinks are less than you need but not far from what you need.
Uriah

[a.wayne]

Originally Posted by udailey

I wish I had info to share but they have not got back to me yet. However I have to agree with bear. Airflow may be necessary. I dont think it will need much though. Even a breeze will help A LOT. Computer fans are getting very very quiet. I recently got one for about 4 bucks to waft away solder fumes. Running it on a battery and a pot. I cant hear it at all even two foot from it. I would put them below pointing up. I think it would do it because I think those sinks are less than you need but not far from what you need.
Uriah

Agree ! My intention is to run fans also ....

[bear]

My LR is dead quiet.
I am in the country.
60Hz. transformer hum can seem deafening late at night especially in the winter when there are no bugs to make outside noises.

Fans are problematic. At least have the fan operation controlled by a thermistor for speed control or worst case a thermal switch or two with either resistor or control of the set pin of a 3 pin vreg so that it is quiet until it gets hot...

The quietest fans are "squirrel cage" blowers. You'd want one that is oversized and then run it way below it's intended speed, like crawling around.

I am considering doing just this via something like a clock motor or other very quiet low RPM motor and run the blower via a rubber "O ring" belt for decoupling ... not much breeze is a lot more cooling than natural convection...

_-_-

[ma_coule]

Originally Posted by bear

...other very quiet low RPM motor...

Hi bear,
what do you mean?
Maybe something like that:
Scythe Kaze Jyu Slim 1000, 100x100x12mm, 1000rpm, 25.58m³/h, 14.5dB.
Cheers,

[umut1001]

Has anyone tried using audio input transformer with F5?I do not know much about audio transformers but my friend said that it is better than using capacitors.I have a laptop that have headphone output.If i use transformer with x3 gain how can it be? Which transformer can i use 10-20$ price range ?thank you

107H Hammond Miniature Epoxy Potted Audio transformer - eBay (item 180398802167 end time Feb-15-10 22:32:28 PST) Is it reliable?

[labjr]

The F5 doesn't have a capacitor input. Why do you want to use a transformer?

[umut1001]

Ok sorry.It is only for gain.My laptop has headphone output but it is not enough.I need to get 3-4x gain