IME -458 SPRING 2014FINAL PROJECT

FABIANO REUTERMECHANICAL ENGINEERING

CK 1000 LIGHT ALARM Project

The CK1000 Sounds an alarm when light is detected using the following: HEF14011B IC , a 4 NAND Gate IC -handles logic Photoconductive photocell a.k.a. Light dependent

resistor (LDR)- senses light Trimpot potentiometer- adjusts resistance in “tank”

circuit

Design

Logic Circuit

• The HEF14011B IC, also known as 14-pin dual inline package (14-DIP), is a quad NAND gate interconnect (there are 4 of them), 2 inputs, 2 outputs.

• It is wired up to oscillate when the input to it goes high, that is the BC557 transistor (Q2) turns on after light is detected by the LDR. The oscillating output from the HEF14011B IC turns the BC547 transistor (Q1) on and off.

• When Q1 is ON, the tank circuit (the choke and the piezo buzzer), charges up. When the Q1 turns OFF the piezo (which acts as a capacitor) discharges into the choke and makes a 'click' as it does so.

Sensing Light

The PDV-P7002 are (CdS), photoconductive photocells designed to sense light from 400 to 700 nm. These light dependent resistors (LDR) are available in a wide range of resistance values. They are packaged in a two leaded plastic-coated ceramic header.

PCB Schematic

PCB Layout

Finished Product

AssemblyAll components are through-holeSoldered to boardComponents arranged with DIP Trace to

minimize board size.DIP-14 Mount allows for replacement of the

IC unit in case of damage.

Wooden Chest

Sound turns off in about 3-5 seconds after lid is shut.

Questions?