This page contains various more or less documented (small) electronic circuits.
If you have some usefull schematics lying around, please send'em and they'll be included on this page.

Smartcard programmer	Very simple smartcard (16x84/EEPROM based) programmer, for use with, (and powered by), a standard COM-port.
Linedriven offhook detector	Small, linedriven circuit for use on the PSTN. Shows if the line is in use (if a parallel-connected phone is off-hook).