Dilshan R Jayakody’s Web Log

This is a simple electronic project which we implemented for some local event to guide audience automatically with some prerecorded voice messages. The core component of this unit is ISD1820PY voice record/playback chip which is manufactured by Nuvoton Technologies . Except for ISD1820PY, this unit use commonly available low power LASER and LDR assembly to detect people. To drive the loudspeaker we use popular LM386 audio power amplifier. Thanks to ISD1820PY and LM386 this system can be implemented on a breadboard or on stripboard with a minimum number of external components. This circuit is designed to drive using 6V or 9V DC battery but it can also drive with 6V or 9V DC regulated power supply. To get 3.3V we use an LD1117V33 voltage regulator, but this can also be replaced with some commonly available 3.3V regulators such as LD33V, MC33269-3.3, etc. For the speaker, we use 4-inch 8Ω full-range speaker. A prototype version of electronic voice messenger. This unit can be u...

These days many verities of alarm systems are available in the market. Some of them get triggered through touch and some type where a wire needs to broken to get triggered.  Both of these types of alarms have some limitations and problems. Wire based alarms are easily avoidable, noticeable and need some regular maintenance. Touch type alarms often pickup RF waves and get activated (because of that it need some controlled environment to function properly). In this project we design and develop LASER based burglar alarm system. Instead of wire(s) this system use LASER light wave and it can effective for more than 50m. Core features of this alarm system are: High audio output power (Max. 3W PMPO) Master light override switch Inbuilt alarm test functionality Memorized power state Quick response time (aprox. 10ms ~ 30ms) Support for wide input voltage range (15V – 25V DC) Easy to build and calibrate Compact size (aprox. 130 × 200 × 60mm) This alarm system is specifically ...