3 Terminated regulator?????

[Stewart Pye]

Howdy....

I'd just run wires to a TO220 reg, bolting it to somewhere handy (with an
insulator), and possibly a heatsink.


Regards, 

Stewart Pye.

At 02:02 PM 22/01/2000 +1000, Batz Goodfortune wrote:
>Y-ellow Y'all.
>	Ok so I've just spent the past month re-writing the mixer firmware from
>scratch. The vary moment I blow the firmware into the chip and plug it in,
>the hardware dies. Needless to say I went to bed before impulse took me to
>the garden shed. Where upon I would have retrieved the 10 pound Sledge and
>done my worst.
>
>The morning brought a revelation. When powering it back up the system came
>to life. Then it dawned on me. The mixer had been turned on all the
>previous day. It was hot. The little 78L/79L regulators probably thermally
>shut down. With the addition of a quad op-amp package to the system for a
>balanced output, the little regulators were probably right on the edge. The
>whole thing should have been under 100mA but being on for a significant
>amount of time, saw them heat up just enough to go. "Ah Aar.  I'm just not
>going to play this game any more." And shut down. Obviously I need to put a
>bigger reg in there. A 78M at least. Should they still make such things?
>
>The problem is that whilst I plan to totally re-design the boards for many
>reasons, and could accommodate the new regs on the new boards, I don't have
>room on the prototype. Vertically, horizontally, anyway you look at it, I
>just can't get a TO220 in there. 
>
>Now I know that designs often call for TO92 transistors to be in thermal
>contact with something else for thermal regulation. Such as oscillators and
>biasing in power amps etc. What I'm considering is getting one of those
>little heat sinks from Can-package transistors (I don't know what they call
>those. they're like a TO5  with a built in radial heat sink.) and hijack a
>pair to try and retrofit them to the 78L/79L regulators. A kind of stop-gap
>measure.
>
>They're TO92 plastic packages so I'm not sure how effective this would be.
>Whether it's worth destroying two perfectly good transistors (and all the
>associated trouble I'd have to go to) in order to try and cool 2 TO92
>regulators. Anyone have any comments on this?
>
>There's virtually no air flow in the system... Am I wasting my time here?
>Remember this is just to keep the prototype running. I'll do it properly on
>the final item.
>
>Thanks in advance.
>
>be absolutely Icebox.
>
> _ __        _                              
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>