Re: BJT recommendation?

From: Walter Harley (walterh_at_cafewalterNOSPAM.com)
Date: 03/24/05 

Date: Thu, 24 Mar 2005 08:35:14 -0800

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:114535pd7eb7k50@corp.supernews.com...
>
> "Walter Harley" <walterh@cafewalterNOSPAM.com> wrote in message
> news:UN-dnVO829BQ99_fRVn-qQ@speakeasy.net...
>> hfe around 100 - 300 [...] need to be able to dissipate 700mW
>> continuously (inside a small chassis), without damage.
>
> Well, they're right under your nose. The 2N2219A and the 2N2905A are
> the same chips as the 2N2222A and 2N2907A, but they're in a TO-5 can and
> can dissipate something like 800mW. Sounds just right to me.

I'd be hesitant to pump 700mW through a device rated for only 800mW, in a
closed airspace. Those ratings are based on 25C ambient right next to the
device; in closed airspace, the air heats up, and you have to derate. I'd
feel more comfortable with something rated at least 1W.

> If you're willing to use Pro Electron Euro parts, the BD135 and BD136 or
> other numbers in the same series will do the trick.

Package looks perfect! It looks like min hfe is kind of low, but typical
hfe is decent; I might have to hand-screen, which would be a pain. Mouser
shows "non-stocked item"; Digikey doesn't list them. Nonetheless, I'll do a
bit of hunting for them; they might do the trick. Thanks.