Just sharing....
You know the little hole in a TO220 tab?
Just a 1/2" to 1" machine screw with nut tightened to it does a very respectable job of sinking heat.
Stays in place well and doesn't shift either like the press on types at a sub-penny price. Of course, you need to have the room for the screw to protrude.
Anyone else do this?
(snip)
You should have a quantitative idea of how much additional power this bolt gets rid of, by doing some testing. I guess the 1/2 inch long one adds a quarter watt of capability and the 1 inch one adds a little more than a half watt, at maximum allowable temperature. Not much help for that much ugly. And not better than the watt or so capability of small clip on heat sinks.
A TO-220 on no heat sink, at right angles to the board gets rid of about 2 watts if it is 100C above ambient, but something like 40 watts if it is mounted om a huge heat sink. So, I think your bolt idea is incrementally helpful.
My favorite trick, like this, for axial lead diodes, is to solder a small loop in the lead, before soldering it into a board, giving it Mickey Mouse ears. Also incremental, but there is no real good alternative for heat sinking axial leaded parts, except for soldering them between copper planes.
-- Regards, John Popelish
I used to use the transistor as a mounting point for the board and use a spacer and place the heat sink side of the transistor touching the chassis with and insulator if needed.
Bob
I like the fender washer idea.
There available in a zillion sizes and CHEAP.
I use threaded spacers as heatsinks fairly often. It is the same idea but lighter for how much heat it can carry way. If you put the screw in from below the PCB, it will works as the holding nut and the heatsink too.
On Mar 9, 7:32 am, John Popelish wrote: [....]
You can solder brass washers onto their legs.
You can stand them up and solder them to a brass object of some kind.
You can put them on the back of the PCB and press them down onto Gappad
Somewhere I saw a board that had long slots routed for the diodes (generous air space on each side of the cylinder), with the rather long leads soldered onto large copper pours (maybe a square inch, each).
I guess you can get something like 6 amps average from a large axial silicon diode that way, without mounting a heat sink. Cheap, but it eats board area.
-- Regards, John Popelish
I would also attach a thin piece of aluminum I cut to whatever heat dissipation is needed. If its flat on a board, I would try a brass screw.
greg
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