Posted by Circuits Arena on Wednesday, 11 May 2016
Electronic Alarm Reminder Circuit is the artlcle explaining Electronic Alarm Reminder Circuit This easy-to-build electronic alarm will remind you of an impotant task after a preset time. It...
Electronic Alarm Reminder Circuit
This easy-to-build electronic alarm will remind you of an impotant task after a preset time. It is particularly useful for housewives and busy professionals. All you have to do is set the time in minute swith the help of two thumbwheel switches (S3 and S4) and press and release start switch. Precisely after the time set by you is over, there is an audio as well as visual indication to remind you that the time you set has elapsed. The gadget is portable and operates off a 9V battery.
At the heart of this circuit are two counter ICs CD4029 (IC4 and IC5). These are programmable up/down 4bit binary/decade counters belonging to CMOS family of digital integrated circuits. The information present on them is fed to inputs P0 through P3 in parallel. It is loaded into the counter when the PL input is high, independent of the clock pulse input. In this circuit, IC4 and IC5 count in up/down mode when the up/down input is high/low. These have been wired as 4-bit binary counters in countdown mode with B/D input low. The counter advances by one count on every low-to-high transition of the clock pulse.
