[sdiy] [AH] Re: UA726 clone possible?

[Tom Wiltshire]

Somebody already mentioned the DMMT3904 matched pair:

	http://www.farnell.com/datasheets/1915879.pdf

This is available in a SOT363 package, 2 mm × 1.25 mm.

However, the other transistors in the circuit (the non-matched ones) could be something like this:

	http://www.farnell.com/datasheets/1912209.pdf

These are a truly ridiculous SOT963 package, 1mm x 1mm!

Getting the size small enough looks like it might be feasible. Finding the parts after you drop them on the carpet won't be!

Tom


On 10 Sep 2015, at 23:26, Tom Bugs <admin at bugbrand.co.uk> wrote:

> Well, yes, it is a learning project driven by curiousity rather than particular need & hopefully I can get some learnings along the way..
> My understanding is that the CA/LM3046 has lower specs for the matched pair than the LS318 (or similar AD NPN pairs) - though of course it has been used in a heater arrangement in quite a few commercial synths over the years.
> I would think that the heater element needs to produce a stable temperature (somewhere above ambient) and this temperature needs to be efficectively coupled to the matched pair - I would hope that as long as the device is potted (or using the heat transfer epoxy compound I have) this will be sufficient.
> It could equally be possible to have all components on one side and have the PCB overhang the ua726 footprint (the current design already does a little).
> Cheers, Tom
>