[sdiy] CA3086 and CA3046?

[Jim Patchell]

Christian wrote:

>
> I managed to get quite a few (10) 3086's and I shall test the
> transistors to attempt to get the best match. When all said and done,
> if the VCO works and is stable then it doesn't matter what you use.
> If she drifts like a ship lost at sea then I shall think again.
>

    The 3086 is exactly the same die...just not tested for matching.  I am
willing to be you will find they match quite well.

>
> Another question. Anyone doing anything fancy with Pin 13 (substrate)?
> I am currently tying all spare transistor bases and emitters to ground
> (which includes that pin).
>

    Pin 13 MUST go to the lowest DC potential that any of the pins on the CA3046
will see.  The transistors are isolated with basically a reversed biased diode
junction.  You also have to remember that the breakdown voltage of this part is
only 20 volts, so choose wisely, although, I have stretched this and have run
them at 27.5 volts.  What I really need to do myself is set up a little rig to
test the breakdown voltage....

>
>
> Thanks
> Christian.

    -Jim