We found this circuit in the August 1990 issue of Radio Electronics magazine. The two-digit circuit uses a pressure sensor and is powered by a 9V battery.
Found in Philips' 90s documentation, this small source can use modern transistors like the BD135...
This circuit is designed to activate an automotive alarm after 8 minutes of activation. Of course...
June 2016 - It can be purchased from Mouser Electronics the new triacs Z04 for 4 A from...