F5 power amplifier

[labjr]

I think you would need a high quality transformer like Jensen. However, I don't imagine your laptop will output good quality sound. I would try an external DAC instead.

[woodturner-fran]

Nelson has a very nice and simple circuit for controlling a fan. It uses a most and the idea is that the fan gets a shot of current to get it running but then runs at ow rpm afterwards. I think the issue was that while you get the fans running slow enough to be quiet,they won't start .

I'll see if I can find it.....


Fran

[umut1001]

Originally Posted by labjr

I think you would need a high quality transformer like Jensen. However, I don't imagine your laptop will output good quality sound. I would try an external DAC instead.

My laptop sounds nice to me.It sounds not as quality as but warmer than my emu1212m card.I will try jensen.What should input and output impedance be ?

[jackinnj]

Originally Posted by bear

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...

You're not kidding -- fans used to be a primary cause of power supply failure for telcos -- at least according to the guys who sold heat sinks!

The fan on our built in fridge just got replaced -- of course prior to this the micro-controller board was fried by a power transient, this caused the alternator board to fail as the thermal protection didn't kick in (yes, Kitchen-Aid uses a 3-phase fan, and they derive this with an SMPS) -- the failures all relate to the fan bushing which suffers premature wear. They also run these high efficiency appliance compressor fans "hot" which means shortening MTBF.

Go figure -- I run an Audio Research D-115, with a bunch of 6550's most of the time to keep the living room warm, and 4 F5's here in the lab to keep it warm and good-sounding.

[woodturner-fran]

heres that circuit - I used it to run 2 x 3" fans on the case of my mini-aleph (which I had biased the hell out of!).

It works.... but I've missed all this part about using what looks like cpu heatsinks. I would imagine for the few dollars you'd save, you'd be better served by a big chunk o' heatsink......



Fran

[a.wayne]

Originally Posted by woodturner-fran

heres that circuit - I used it to run 2 x 3" fans on the case of my mini-aleph (which I had biased the hell out of!).

It works.... but I've missed all this part about using what looks like cpu heatsinks. I would imagine for the few dollars you'd save, you'd be better served by a big chunk o' heatsink......



Fran

what controls the fan on/off via temps ....

[woodturner-fran]

No, the fan runs continuously..... but you can adjust it to low enough speeds with this circuit and it will always start. Given that the F5 produces a fairly constant amount of heat, you are going to need it running all the time anyway with undersized/forced air heatsinks.

Fran

[tinitus]

umut1001

There have been a member having trouble with connecting F5 to CD player having trafo output

Dont know if it was due to induction or whatever
I dont think i was ever stated whether it was due to the line trafo
But he did have another CD with ordinary output, and had no problem with that one

[cviller]

The F5 has very high input impedance - could be the reason.

[umut1001]

yeah maybe.Should measure input and output impedances of trafo