I'm new to the DIY audio scene and I haven't figured out good sources for some of the parts I need (I'm going to be building the 3886 kit from www.chipamp.com). In particular...
A relatively inexpensive chassis. The best I've come up with so far is some from jameco.com. They fit the need and are cheap I suppose, but I'm wondering if there are other good options out there.
A stereo potentiometer. No source on this yet.
Heatsinks
Electronics miscellany. Like those very handy looking terminal strips I see running down the middle of some of the completed amps in the gallery at www.chipamp.com.
A relatively inexpensive chassis. The best I've come up with so far is some from jameco.com. They fit the need and are cheap I suppose, but I'm wondering if there are other good options out there.
A stereo potentiometer. No source on this yet.
Heatsinks
Electronics miscellany. Like those very handy looking terminal strips I see running down the middle of some of the completed amps in the gallery at www.chipamp.com.
http://www.circuitspecialists.com/prod.itml/icOid/3521
This place has several options for nice low priced enclosers. But try to order as much as possible at any one time to compensate for the shipping. They stick you on the shipping.
This place has several options for nice low priced enclosers. But try to order as much as possible at any one time to compensate for the shipping. They stick you on the shipping.
Preiter:
Alltronics has some decent enclosures -- I used one of these for my Foreplay: http://www.alltronics.com/cgi-bin/category.cgi?item=RC3120A&type=store
Regards,
Scott
Alltronics has some decent enclosures -- I used one of these for my Foreplay: http://www.alltronics.com/cgi-bin/category.cgi?item=RC3120A&type=store
Regards,
Scott
jerishi said:lots of choices for chassis... try local goodwill/ salvation army... then try looking at various ways of implementing ideas within (chosen) design ideas. It's the details that'll cause one to keep trying to get it 'perfect'... and then you're stuck. Good Luck.
While the Goodwill and SA get picked over by the tube (vacuum state) guys, you can pick up a used CD player for a couple of bucks -- just discard all the innards -- keep the power connector, etc. CD Players, like the Denons, were pretty well put together (mechanically).
you can use a small piece of Formica laminate for the front panel --this is easy to drill -- mount over the existing front panel with contact adhesive. For an amplifier you only need "ON" and "OFF" control.
My dual LM4780 120 watt bridged amp is housed in a very nice Lambda rack-mount power supply cabinet -- it was around $10
Hi ,
If you don't want hot heat sink , you must use a very large one or fans.
70 degrees celsius is quite hot to touch(still it is possible to hold fingers on it) , but is no problem at all for ICs.
If you want good thermal conductivity , mica can be used as insulator.But you will have to split it with a sharp knife to make thermal resistance smaller.For sure , thermal paste is required with it.
I think that best mounting technique is something similar to shown in picture ; it would provide more uniform force than standard bolt.Also , there is no risk of break-down between insulator and heat sink where bolt goes , if a small metal dust gets in there.
Hope this helps,
Lukas.
If you don't want hot heat sink , you must use a very large one or fans.
70 degrees celsius is quite hot to touch(still it is possible to hold fingers on it) , but is no problem at all for ICs.
If you want good thermal conductivity , mica can be used as insulator.But you will have to split it with a sharp knife to make thermal resistance smaller.For sure , thermal paste is required with it.
I think that best mounting technique is something similar to shown in picture ; it would provide more uniform force than standard bolt.Also , there is no risk of break-down between insulator and heat sink where bolt goes , if a small metal dust gets in there.
Hope this helps,
Lukas.
Attachments
you can find the "dissipation calculator" on National's website or on the data-sheet for the chip -- then use the Aavid Thermalloy heatsink calculator to work backwards the dimensions -- use 32 LFM as the velocity of air in a room.
http://www.aavidthermalloy.com/technical/thermal.shtml
here's an LM4780 on a 12 inch heatsink -- all greased up and ready to go:
and a pair of them in a 2X120Watt configuration -- using 2 heat sinks as an air tunnel:
http://www.aavidthermalloy.com/technical/thermal.shtml
here's an LM4780 on a 12 inch heatsink -- all greased up and ready to go:
An externally hosted image should be here but it was not working when we last tested it.
and a pair of them in a 2X120Watt configuration -- using 2 heat sinks as an air tunnel:
An externally hosted image should be here but it was not working when we last tested it.
David...
I have some insulating strips. for the LM 3886T
and the others without the TF backs
email me your address and I'll send you a length
no charge
Steve @ Apex Jr.
steve.apexjr@prodigy.net
I have some insulating strips. for the LM 3886T
and the others without the TF backs
email me your address and I'll send you a length
no charge
Steve @ Apex Jr.
steve.apexjr@prodigy.net
davidlzimmer said:Now my heatsink won't be "live" and I can mount them in an enclosure.
for others...
LM3886TF = isolated (plastic) backing, so it doesn't make your heatsink "hot"...
LM3886T = metal case backing
either way, it's low voltage...
elementx said:
for others...
LM3886TF = isolated (plastic) backing, so it doesn't make your heatsink "hot"...
which, translated, means that it's heat transfer from the semiconductor junction to the outside world is less efficient. TF devices should be used at lower voltages, or with a larger heat sink.
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