This is Electronic Stethoscope circuits. Usually the stethoscope is a medical device that listens to the heartbeat. Which we can make it with the least amount of electronic equipment so easy to make. Read more
Here are simple electronic siren circuits using transistors suitable for a beginner learning electronics. It only requires 6V to 12V power. Read more
Here is five burglar alarm circuits for you can look as idea To protect their property from thieves. simple switching, vibration systems, touch-sensitive. Read more
See Intercom circuit using LM386 and other IC. louder transistor version. And easy and cheap. With Condenser MIC and Speaker, longer cable. Read more
The Mouse and Rat repellent circuit using astable multivibrator which use sound waves or ultrasonic so it escaped away. Use transistor and piezoelectric. Read more