Nagpur, Maharashtra, India
Our Products
Leading Manufacturer, Supplier & Retailer of PC Based Automated School Bell With Counter, LED Dancing Light, Door Knock Musical Alarm, Microcontroller Based Smoke And Fire Detector Cum Alarm and Ultrasonic Sound Burglar Alarm.
PC Based Automated School Bell With Counter gives bell after 45 min with interval of 30 min. It also keeps a track of time interval. This is the automated type of school/college bell, which controls through program written in ‘C’ language. The program is designed for total 8 periods. The circuit automatically rings bell every after 45 minutes for first four periods. Then it gives interval of 30 minutes. After interval, bell rings again, after every 45 minutes for remaining four periods. The time period of ringing the bell is set at 5 seconds. The time duration can be modified according to requirement by simple modifications in the program. In addition the counter is designed which counts the time in minutes and display is shown on two 7-segment display. Thus when first period is over, the display shows ‘45’ and so on for remaining period. For interval also, the display shows ‘30’. As stated earlier you can also modify the time periods by simple modifications in the program.
About the Circuit :The interfacing circuit is shown in the diagram with PC’s parallel port. When program is executed, the program gives the message as: “This is the program of Automated School/College Bell with Counter. Press any key to continue…”
After some interval, program generate control signal at port-3. As port-3 is connected to clock-input of counter IC, it starts counting. The duration of clock pulse is set at 1minute in the program. After 45 minutes, counting stops and display shows ‘45’ on two 7-segment display, which is driven by counter ICs. At the same time program generate control signal at port-2. Transistor T1 drives opt isolator IC3. As a result TRIAC gets triggered and bell connected at its output rings. After this the control goes to port-4 which is connected to reset input of counter IC. As a result counter reset and display shows ‘00’ for very few seconds and again cycle repeats for next period. This procedure repeats for first four periods. Then it gives interval of 30 minutes. For this control signal generates as above but the duration is of 30 minutes and display shows ‘30’ on 7-segment display. After interval, the cycle again repeats for remaining four periods. When the program is in execution on screen, you can read messages as “Period 1 is going on”. When it is over the program gives message “Period 1 is over”. These messages are given for every period and interval also. Thus you are able to know what is going on.
LED Dancing Light is a simple 6 LEDs multi vibrator using two transistor, to give dancing light effect. LED Dancing Light is the base of LED Flashing circuit. LED Dancing Light works on the principle of charging and discharging of capacitors C1 and C2. Current from the positive of battery flows through first set of LEDs D3, D4, D5, D6, D7, D11, D12 to the collector of T2 through resistor R2, R4, R6. Resistor R2, R4, R6 limits current through the LEDs to protect them. The current through R2, R4, and R6 charges capacitor C1. It then discharges through the base of T1 and resistor R9. This gives base current to T1 and it conducts. As a result, second set of LEDs D1, D2, D5, D6, D9, D10, D13, and D14 lights as the current flows through T1. Capacitor C2 again charges and the cycle repeats. The D1, D2, D5, D6, D9, D10, D13, D14 are red LEDs and D3, D4, D5, D6, D7, D11, D12 are the green LEDs. These LEDs flashes alternately and give dancing effect.
Door Knock Musical Alarm is fitted with a Piezoelectric element that senses door knock and starts a melodious sound. This low-cost circuit uses the piezoelectric element of a piezo buzzer as the input sensor. The piezoelectric element plate is fixed at the centre of the door wing by using a cello tape. Apply a small quantity of adhesive at the edges between the plate and the door. Extend wires about 1-1.5 meters from the piezoelectric to the circuit. IC NE555 (IC1) is configured in monostable mode. When it gets an input pulse its output goes high for a period set by VR1, resistor R5 and capacitor C3. IC UM66 (IC2) is used as a melody generator. When the door is knocked at, the piezo plate generates an input pulse, which is amplified by transistor T1. The amplified signal triggers the timer IC NE555 and its output pin 3 goes high to enable the melody generator. Music is heard from the speaker LS1. After the set time period, the melody sound stops. Assemble the circuit on a PCB and enclose in a suitable case. Fix the piezo element at the door and place the speaker in a central room inside the house using long wires. The circuit works off 9-12V DC. The music time can be adjusted through VR1 by changing the R-C time constant of the timer.
Microcontroller Based Smoke And Fire Detector Cum Alarm is used to detect Fire and Smoke and give alarm when either of them occurs. This circuit is often used in Industries to detect fire and smoke that may occur at the site of hazardous processes (AT89C51). We have used ATMEL 89C51 microcontroller which has 4 Kbytes of programmable memory.
The AT89C51 provides the following standard features : 4K bytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bit timer/counters, five vector two-level interrupt architecture, a full duplex serial port, and on-chip oscillator and clock circuitry. Pin Description VCC Supply voltage (GND Ground). Port 0 Port 0 is an 8-bit open drain bidirectional I/O port. As an output port each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high-impedance inputs. Port 0 may also be configured to be the multiplexed low-order address/data bus during accesses to external program and data memory. In this mode P0 has internal pull-ups. Port 0 also receives the code bytes during Flash programming, and outputs the code bytes during program verification. External pull-ups are required during program verification.
Working of the circuit : We have interfaced the LCD to the port 0 and 2. The data is sent on P0 while the control signals for the LCD move on Port 2 pin 0, 1, and 2.
The detail functions of each of the pins are as shown below : Pin no. 18 and 19 are connected to the crystal. The function of crystal is to give pulses to the microcontroller which allows the microcontroller to do various calculations. Pin no. 9 of the microcontroller is connected to +5v through a capacitor of 10uF/50v. This causes the microcontroller to reset at Power ON and to begin execution of program from the first line. (P2.4), (P2.5) are connected to switches S1 and S2 while the other end of switches are connected to Ground. So when a button is pressed the port pins P2.4 and P2.5 get a low depending on which button is pressed and the software inside the microcontroller can take appropriate action. IC 7805 is a voltage regulator IC. It is connected in the input voltage line and limits the voltage to +5v to the circuit. Even if the input voltage goes high up to 14 volts, this IC gives only +5v to the circuit thus preventing any damage. Port 1.0 is connected to the Smoke Circuit and Port 1.1 is connected to fire circuit. The microcontroller receives the logic signal from the smoke / fire circuit when the Smoke or Fire is detected. This logic signal is read by the software and indication is given on Channel 1 or Channel 2. We have used a Hooter on Port 3.0 through a relay which is also activated on detection of smoke / fire. Two keys SW1 and SW2 are connected to the microcontroller port 2.4 and 2.5. These are used to stop the hooter (relay on Port 3.0) for smoke and fire respectively. The LCD will display ‘Channel 1 alarm activated’ when Smoke is detected and ‘Channel 2 alarm activated’ when Fire is detected. In normal case of operation the LCD will display ‘Normal Operation’. The software is written in C language.
Ultrasonic Sound Burglar Alarm gives alarm on interruption of Ultrasonic sound beam. The circuit arrangement for an ultrasonic burglar security system operates in accordance with the Doppler principle and comprises a transmitting transducer which is fed from an oscillator with an ac voltage and continuously transmits ultrasonic radiation during operation, a receiving transducer and a receiving circuit connected thereto and having an analysis circuit and a phase detector which continuously compares the signal received by the receiving transducer with the oscillator ac voltage to form a detection signal which is dependent upon the mutual phase angle. The detection signal is fed to the analysis circuit which responds to the ac component thereof. The circuit arrangement includes a phase-locked loop (PLL) which includes a further detector, a low-pass filter following the phase detector and an oscillator. The oscillator has its frequency controlled at a control input and may be formed as a voltage controlled oscillator (VCO). The cut-off frequency of the low-pass filter is designed to be such that only signals which can pass fundamentally without reduction are those whose frequency is lower than a critical frequency F.sub.c =c/E, where c is the speed of sound of the ultrasonic radiation in the area and E is the path of the ultrasonic radiation from the transmitting transducer to a reflective object located in the predetermined maximum range and back to the receiving transducer.
Ultrasonic Sound Burglar Alarm is an ultrasonic alarm, also known as a silent alarm. This system that lets out a siren that's inaudible to the human ear. Banks typically use these types of systems. As far as home security goes, having a quick response team in place like the system's corresponding call center is an essential part of this setup. This device uses sound waves that act as motion sensors within the home. The waves are projected in beams which bounce across a room's surface areas. Passive infrared detector beams are the most commonly used, capable of detecting activity, as well as temperature changes. These beams are projected out into a room's space using a coverage lens. How this lens is configured will determine how these beams are dispersed throughout the room. As these are highly sensitive systems, proper positioning and adjustment is necessary to avoid false alarms caused by sunlight and heating systems. This unique Ultrasonic Sound Burglar Alarm makes use of the invisible, inaudible ultrasonic sound beam to detect movements. Ultrasonic transducers operate at maximum efficiency when driven at 40 kHz frequency. So an ultrasonic transmitter and receiver pair operating at 40 kHz is used to control the buzzer or the relay. The transmitter unit is built around CMOS IC CD4001 (see Fig. 1). By adjusting the 22-kilo-ohm preset (VR1), the oscillator frequency can be set to approximately 40 kHz. The ultrasonic transmitter transducer is driven by two complementary buffer stages of CD4001 and its current drain is very low. The receiver unit uses a two-stage 40 kHz preamplifier followed by switching circuit, buzzer driver, etc (see Fig. 2). Adjust VR2 in the receiver circuit till the buzzer stops sounding while the receiver senses ultrasonic sound from the transmitter. When the ultrasonic beam is interrupted by the movement of a person or any other object crossing its path, NPN transistor T4 stops conducting and transistor T5 conducts. It activates the buzzer and LED1 for three to four seconds. This duration depends on the time taken by 470µF capacitor (C9) connected at the base of transistor T5 to discharge fully through resistor R14. The burglar alarm duration can be set to a desired value with the values of C9 and R14.The alarm circuit comprising transmitter, receiver and associated circuits operates off a 9-12V regulated power supply. The receiver circuit requires regulated 12V. You can also use unregulated power supply here. Align the ultrasonic transducer such that the signal falls directly on the ultrasonic receiver. The piezobuzzer (BZ1) can be replaced with a relay to control the mains-operated alarm.
Every person wants security from an unknown person in the absence specially when children are at home. Two Way Communication Security System For Household is the specially designed circuit for such type of security. The circuit is built around infrared transmitter and receiver and intercom circuit. When any object interrupts, the infrared signal transmitted by infrared transmitter the infrared sensor in receiver circuit detects this and energizes the relay connected at the output section of the infrared receiver. As relay is, energized melody generator circuit starts generating the melody sound. Thus people inside the house gets alert that someone is at your gate. Now for your security you can start communication with that unknown person. The arrangement of speaker and microphone are such that you can easily communicate with the person outside your house. Thus you are secured from an unknown person.
About the Circuit : The circuit is built around infrared transmitter and receiver, melody generator circuit and two way communication circuit as shown in the circuit diagram.
Transmitter circuit : Two Way Communication Security System For Household consists of a timer IC as IC1 connected as an astable multi vibrator, driving an output transistor, which switches the IR LED D1, ON, & OFF. The duration of the transmitted light pulses is about 10ms and the repetition rate is just less than 1 KHz. The sensitivity is adjusted by adjusting preset P1.
The power supply for the transmitter is not critical provided the output voltage is not greater than 9V as this could result in the maximum current rating of D1.
Receiver Circuit : Receiver section comprises power supply an infrared detector module, time delay circuit with noise filter, bistable flip-flop and an output section. The infrared sensor is used for sensing the IR signal from the transmitter section. In normal operation i.e. without any interruption output at pin2 of IR sensor are high, T2 remains OFF. IC4 is not triggered. When any object interrupts the IR beam falling on sensor, pin2 goes low. Transistor T2 turns ON. Consequently, capacitor C5 starts charging through resistor R9. When voltage across capacitor C5 reaches about 3.5V, pin2 of IC4 receives a high pulse. As IC4 is two input EX-OR Gate, output at pin 3 goes high. Transistor T3 conducts and low pulse is applied to trigger pin2 of IC5. IC5 being operated in monostable mode gets triggered. Output at pin3 of IC5 goes high and relay is energized. LED D2 glows which gives visual indication. Pin 3 remains high for a time set by R12/P2/C9. This time delay is set by preset P2. The NO (Normally Open) output of relay is given to melody generator circuit, which receives supply through relay. The melody sound is heard till relay is ON. Thus, the unknown person is detected through melody sound. When ON signal is available output of sensor goes high and T2 is switched OFF. Now capacitor C5 starts discharging through R8 and voltage across it decreases to zero. When another signal arrives capacitor, C5 again charges through R9 and IC4 gets triggered again. IC3 is a regulator IC that provides a regulated voltage.
Now the communication starts. The communication circuit is built around amplifier IC as IC6 and tone generator is designed using astable multivibrator IC7. As there is a two-way communication, two sets are designed. Sound signals generated due to communication are received by condenser MIC connected at audio input pin2 of IC6/IC8. These signals are amplified by audio amplifier and the amplified output generated at pin6 is given to transistor T5 and T6. The signal is again amplified and the final output is given to speaker. There is also a volume control that, can be set with the help of preset P3/P4. Switches S1 and S2 are used to start the communication. When S1 is, pressed IC7 gets triggered and oscillations start. These oscillations acts as tone input to IC6.
Digital Programmable Bell that we provide is used in various educational institutes (schools & colleges) in order to mark the beginning & end of classes. Digital Programmable Bell is also used in industries in the form of siren which provides information about the change of shifts. Our Digital Programmable Bell is easy-to-install and known for providing exceptional auditory performance.
