BC847BS (was Re: Components with potential)

[Ian Fritz]

Here are a couple of other ideas from recent catalogs. Mouser carries
the NTE replacement series NTE42,43,44,45 dual pairs. Digi-key carries
Zetec surface-mount pairs -- about a dozen different kinds, including 2
x NPN, 2 x PNP and NPN/PNP.

I've looked at some of the NTE42's. V_be matching was better than I
could measure, i.e. < 0.2 mV. h_fe values were less than speced (at
least according to my multimeter's built-in tester). Values were in the
300-350 range and matched to within 2% or so. For under $2 (US) this
seems like a decent chip.

I've also looked at some recently purchased CA3046 and CA3083 (Harris)
arrays. V_be matching was generally better than .2 mV across *all* the
transistors in each array. Just one out of six 3046 arrays had 
measurable offsets of about 0.5 mV. The 3046's had dissapointing h_fe's
of around 60. This is within spec, but lower than the value of 270
measured on an old LM3046. The 3083's h_fe's were around 200-220.

  Ian

jorgen.bergfors at idg.se wrote:
> 
> >> As a new item they have the BC847/857. It is a matched dual transistor
> from
> >> Philips. It is available as both PNP and NPN and is dirt cheap (SEK
> 2:42 /
> >> $0.30 for one). Has anybody tried these? Unfortunately they only seem
> to be
> >> available in surface mount package (SOT363-6). But it should be
> possible to
> >> solder it to a component carrier and put it in an ordinary IC socket.
> 
> >This is *very* interesting !
> >Especially the pnp pair (which one of the two is it ?).
> >This might be the key to build expo converters for 3080's, or even
> >SSM2040's
> >without matching transistors - hey, if they are SMD, that's at least no
> >disadvantage for *this* application ...
> >I saw it listed at RS Components, too. DM 2,- (one dollar), but still
> >ok if they are what we think they are.
> >There is no description, not even that it is a dual type, just the
> >number and price.
> >Do you have more details ?
> 
> >JH.
> 
> You can get the datasheets from the Philips website
> http://www-us.semiconductors.philips.com/search/.
> Just search for BC847BS and BC857BS. Note that the BS at the end is important.
> It turns out that there are single transistor versions of the BC847/857 too.
> 847 is the NPN and 857 is the PNP (see the analogy to BC547/557?).
> Unfortunately the datasheets don't say much. They say "closely matched current
> gain" but nothing about Ube or any figures. I suppose somebody have to buy a
> bunch and measure. Luckily they are cheap. The price I mentioned is if you buy
> one. If you buy 25 or more, they are even cheaper.
> 
> /Jorgen