Electronic siren circuits  using   transistors
Alarm systems
The siren circuits are what importance in various alarm system. For example, the emergency alert, burglar alarm circuits, Fire alarm circuits, Timer , sensor controls, etc. Today I would like to introduce the simple and economical simple siren circuits. It is suitable for beginners. My son will gradually build this circuit onto the PCB layout. Look at below! 4 Circuits.
IC 4060 Timer project
Mini Projects
This is IC 4060 Timer circuit. When rises time that is set, Suppose set 5 minutes time. after all time to 5 minutes. the circuit will emit a sound of buzzer once.
High Temperature fire Alarm Circuit using transistors
Meters & Detectors
This is high temperature fire alarm circuit, when the temperature rise exceeds the limit, it will sound the siren rang out. It is easy to use with transistor circuit to detects heat. Then, a loud noise of the sirens with IC packages. How it works We uses the combination between Q1 (BC109), which is silicon NPN transistor and Q2 (AC188) which is PNP germanium transistor To detect heat in case of fire. Then, the siren will sound warning beeps. The collector lead of Q1 is connected with Base lead of Q2, while the collector lead of Q2 is connected with …
Motor burn out and under voltage protection
Controls & Timers
This is AC motor burn out protection causes of under voltage input. The principle is simple, it will check for voltage at all times. Normal voltage is 220V AC. If the voltage falls below a preset. Relay will not work and the LED is a warning. Can be set to cut no-off in the voltage during the 168-227V. As AC main in normal level, the relay will be connect to apply AC line to motor. And AC-line fall down lower than 10% of normal voltage the relay will cut of load at once. Until the voltage is restored to its …