Refer: Silicon Chip Magazine May 2013
Stop those annoying and intrusive phone calls when you don't want to be disturbed, say at meal or nap time for example. Set the timer duration between 15 to 120 minutes and the caller will get an engaged signal until the timer times out. Kit supplied with silk-screened PCB, black enclosure (83 x 54 x 31mm) with label, pre-programmed PIC, PCB mount components and phone lead.
Features:
• Five times settings: 15, 30, 60, 90 and 120 minutes
• Time set indication
• Time remaining indication
• Automatically returns phone to ready (on hook) after time-out
• Easy push-button timer setting
• No batteries required
• Works with multiple phone extensions in house.
• End button