On Tue, 18 May 2010 15:04:03 -0700 (PDT), b
put finger to keyboard and composed:

It uses an STK 4152 II, pretty typical design of the period.

FWIW, there is application circuit in the datasheet:
http://www.datasheetarchive.com/pdf-...316/586035.pdf
http://www.acust.narod.ru/files/PDF/STK4152.PDF

- Franc Zabkar
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