A Panic Alarm Circuit is used to send an emergency signal immediately to the people in a nearby location to call for help or to alert them. The possible panic situation can be any, it is not restricted to a few situations. One could possibly keep the push button at a hand reachable distance or comfortable place it to carry out quick action in silence by pressing a single button. The indication of emergency can either be in the form of a visible or audible signal, which can be fixed at a few meters away through a wire.
Add a Teacher Note to share how you incorporated it into your lesson.
Step 1: Required Hardware
The following components have been used:
1. 555 Timer IC – 1
2. Transistor BC547 – 1
3. Buzzer (6-12V) – 1
4. LED – 1
5. Tactile switch – 2
6. 9V Battery with holder – 1.
7. Resistors (10kὨ – 2; 220Ὠ - 1; 1KὨ - 1)
8. Ceramic capacitor(0.01uF) – 1
9. 2 pin connector-1
10. Dc jack -1
Step 2: Circuit Schematic & Working
The image above shows the circuit schematic of the Panic Alarm Button Circuit using 555 Timer IC
There are three popular configurations of 555 timer IC,
1. Astable multivibrator
2. Monostable multivibrator
3. Bistable multivibrator
They differ by the number of stable states in the circuit. In our case, we need two stable states. One state is alarm ON and another one is alarm OFF. So here we have configured 555 in Bistable mode. On pressing a button, a signal should be sent to the location in audible and visible form. In order to turn OFF the alarm we use another button either at our place or at the place of indication. Here a Simple Panic Alarm with a low operating current is done.
Step 3: PCB Design
The image above shows the circuit PCB Design of Panic Alarm Button Circuit using 555 Timer IC
Parameter consideration for PCB design
1. Trace width thickness is minimum 8 mil.
2. The gap between plane copper and copper trace is a minimum of 8 mil.
3. The gap between a trace to trace is a minimum of 8 mil.
4. Minimum drill size is 0.4 mm
5. All the tracks which have current path need thicker traces.
Step 4: Sending the Gerber for Manufacturing
You can draw the PCB Schematic with any software as per your convenience. Here I have my own design and Gerber file attached. After you generate the Gerber file you can send it for fabrication.
I have uploaded it onto LIONCIRCUITS. They are based in India. I would recommend you to order from them. They provide Low-cost prototypes and their UI is really good and easy to use. Just place an online order and get your prototypes in just 6 days.
I will write part-2 of this inscrutable in the coming week after I receive the fabricated board.