Lo-Tech Dissipater

[petemoore]

I was warming up the LM386-1's in the Little Gem MkII [nice amp].
 Yes I should get some JRC LM386-D's [I think that's the #]...but
 At any rate, I'm lookng for a Lo tech heat dissipater technique that doesn't require getting the 'heat sink lube' [white colored heat conductive 'grease'], but instead uses something like what I have around here:
 JB Weld [is this a heat insulator?]
 Super Glue
 Glycol...I don't know how conductive [electrically] anti-freeze is, possibly a very small amout would keep itself 'in place' because of surface tension, at least it won't evaporate...
  Copper: thin plate, and wire [this idea is on the front burner'}...flatten a 386's body length on a stretch of copper wire [bottom bun] under a 386 [meat] and solder the wire to one side of the plate, and tie the other side to the plate...the plate would contact the top of the OA, the wire would contact the bottom, together they wouldd 'clamp' the OA in a sandwuch.
 ...really I'm wondering about conductive Gel or Glue [or {?}], that I'd have around here to make a better heat connection to the OA's body....or any other methods you've tried.

[Arn C.]

How about a little mini fan?

You could possibly shape a sort of heat sink from some aluminum or aluminum foil and adhere it to the underside of the chip and wrap it up and over the top. Get what I am saying?- sort of anything metal, preferably aluminum, as long as it is in contact with the chip it will dissapate the heat off of it.   Just glue it in tiny spots so that most of the aluminum touches the surface without the glue interfering with the transfer of the heat.

Peace!
Arn C.

[petemoore]

Yupp Ill be trying that:
 very non liberal use of adhesive [as I would tend to think epozy is an insulator] and more liberal use of heat sink metal...I might just try to get the epoxy all the way around each side just on the edges by the pins, then touch a tiny amount of glycol in the middle portion.

[petemoore]

Didn't take much.
 To make a big difference.
 I used a 2-1/4'' inch piece of copper sheet, drilled a couple holes in it, soldered a piece of thick-er solid core wire to one hole, super glued the chip to the plate, threaded the wire through the other hole, S. glue also on the bottom tween wire and OA body. cut the copper into 'fan blades', and bent them a bit to let air through.
 Now it has the same heat output at at least a doubling in volume. Just gets warm so far, I have no gain caps [OA 1 & 8] connected, loldefinitely works better when it can be turned up more.
 With everything I like at the front end of the Little Gem, /LP, OS, N.Clipper Wnotch, 1/2 Shaka Tube, EZVibe, SDE 1000Delay,>L.G.MkII>Magnavox 8''Sp.: I've got a really great sound, it really Rocks the Living Room.
 A. big difference is an open back cab on the single speaker, then with the seat pad pushed over the back of it. Gives a great A/B of open/closed back cabs.

[Peter Snowberg]

I would try adding a 470uF NP cap (or back-to-back 1000uF electrolytics) in series with the speaker first beacuse without one there is going to be DC needlessly flowing through the 386s. You might not need to disipate extra heat after that, but if you do, I would use a piece of copper or aluminum with zinc oxide paste. Thermal conductivity is a touchy thing. It sounds like you found something there with the super glue, but I wonder how well it will hold up over time.

You might also want to try 22uF coupling caps between pins 1 and 8. I don't like what a DC path there does to the sound and that might be mis-biasing the output stage, generating even more waste heat.

Take care,
-Peter