Post by zappytheviking on May 16, 2016 16:56:53 GMT
The parts are arriving from all over the globe, there is a pile of notes with ideas, a few good ones hopefully
Just got a veritable truckload of goodies from Colin with a few bonuses, much appreciated.
I will be posting thoughts, picture and progress. Some dumb, some usable, feel free to give me pointers. This is a sizeable project for me but, as it is said, I think I can I think I can .
First on the task list is get the amp and cooling going, test things out. Picking a case, leaning towards having a shop bend 3mm aluminium and doing wooden sides, not sure yet. Getting a passive cooling 20kg behemoth case is not in the budget until later so will be committing HiFi heresy, might as well put PC case LED strips in there, nice red blinky lights.
The PSU and protection boards will get done a few months on, got to dimension the case for it ahead of time.
Wooo excited, I suspect this will displace my old workhorse the illustrious Pioneer A-509R .
Post by zappytheviking on May 16, 2016 17:10:05 GMT
Today started with polishing some old LGA775 heatsinks, get them all nice n spiffy.
Did a test on those heatsinks, they are supposed to handle a 100W TDP CPU. Made an emergency resistor out of kanthal thread that drew 50W, standing up and passive the heatsink got 65C(20C ambient). Totally different story with a fan on it, immediately dropped to 30C. From what I understand the max heat output of a full module is 100w, I assume it's 50W for Fet and 50W for darlington.
I am hoping to put a button on the front of the case, go from passive low power 10W, then switching on fan circuits to get ~30W, thermistor cools down and turns up the juice.
Just flip on the fan circuit and whammo more power. No fans might overheat the PSU board, will have to see when its time, with luck the passive draft will be enough.
Got a bit lazy with the last ones, but hey, they are flat now.
Nice use of CPU coolers there, makes it much lower cost than it might have been. You can run the fans on low voltage (I often run 12V fans on 5V, it makes them whisper quiet but they still do a good job of cooling).
Post by zappytheviking on May 16, 2016 20:15:30 GMT
MartinT Thank you, yes it most certainly was a saving, paid 8e per heatsink. Thats a good tip, I imagined I would need at least 9V. They are 1300rpm fans so they shouldn't be too horrible.
Will start out with 2 fan controller boards from our chinese friends, a bit paranoid they will introduce a bunch of RFI from some junky PWM chip or something, fingers crossed. Also the fan stall alarm is at 7-800rpm .
It doesn't need a fan speed controller, just an NTC thermistor in line with the fan feed, connected to the heat sink.
That would be so much simpler, I tried calculating voltage drops etc. What value, 100ohm? Most of them had a max dissipation of 450mW, voltage drop of ~6v gives 0.7w, so would have to get a few of those , make a little grid. Close?
I remember you can get power thermistors which can bolt onto casework, but I last did this many years ago. Or look at the PC application market where temperature controlled fans often have a thermistor in the air flow.
I used a bridge rectifier and a small cap with a series resistor in the cap not the Fan so the peak volts on the crest are about 15V but the DC due to ripple is only 4.8V, this kicked start the Fan but makes it run slow,now with simple mod a thermistor driving a Emitter Follower would work and thus a small thermistor.
Great thread Zappy, looks like your doing a Stirling job. I've got to get my arse in gear and crack on with my build, but I've had a couple of wee issues to get out of the way first. Best of luck with the build.
Source Components: DDDAC Amplification: Stereo Coffee pre amp on steroids, Rather large Colin Wonfor Class A power Amp Speakers: Lampizator P17 Open Baffles Accessories: Klotz 500 DIY Interconnects & DIY speaker cable sounding better than anything commercial. All powered from a Mother Trucker BPS with a dedicated consumer unit with 10mm armoured radial back to the house tails after the meter.