2SC1815Y is a very popular NPN transister made by Toshiba, and it can be replaced by any which has a current capacity about 150mA. 2SC372, 2SC945, or 2N2222 is a typical replacement. -- Yasuhiko Ohta, Nagoya Institute of Technology Gokiso-cho, Showa-ku, Nagoya 466, Japan +81-52-732-2111, ext.2432, +81-52-733-9979:Fax