BATH ALARM

Here is the block diagram, for a bath alarm which will sound an alarm before the water in the bath overflows:

The float sensor consists of a voltage divider with a float switch at the top and a 100 k pull down resistor at the bottom. If the water level rises above a critical level, the float switch closes and the output of this subsystem becomes HIGH, logic 1.                                                                          
The astable, or pulse generator, produces pulses. Its output alternates repeatedly from HIGH to LOW. The float sensor provides a control input to the AND gate. If the control input is LOW, the output of the AND gate remains LOW. However, if the control input goes HIGH, the output of the AND gate starts to produce pulses, alternately HIGH and LOW, following the astable.
The transducer driver is needed to provide enough current to drive the buzzer. When the bath is full, the buzzer pulses ON and OFF.
It is easy to model this system using the system blocks provided by Crocodile Technology ©:

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Speed Controller For DC Motor

Speed control for dc motor (electric motor) can be implemented using open loop or closed loop. Closed loop controller, also known as servo controller, or a feedback control, gives the best performance since the loop will maintain the actual speed to follow the reference. In simple application, an open loop controller can be enough if the load is constant, such as in fan control (PC fan speed control). This dc motor control circuit uses PWM (pulse width modulation), gives a better efficiency than using linear driver. Here is the schematic diagram of this PWM motor controller. The LM/NE 555 timer is use to generate the PWM pulse which duty cycle is control by the potentiometer use in the circuit.

The report and transient response is download by electrodata.

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DESIGINING OF OVERHEATING ALARM USING 555 TIMER IC

The overheating alarm is use for detecting a high temperature in any system where it is use. It contains a buzzer which is on when a system attain a temperature level. It is simple circuit which have easily installation. Overheat alarm circuit consists a thermistor i.e. a heat sensor which detects the raise on heat and within some mechanism buzzer produces sound. We know thermistor is a kind of resistor,used as heat sensor which offers low resistance at high temperature and high resistance at low temperature and the same concept is used here for detecting overheat. The difference in values of op amp 324 inverting and non inverting terminal voltages  decides the switching on and off for the circuit to drive IC 555 for generating pulse train which produce beep alarm by buzzer.. At normal temperature, the resistance of the Thermistor is approximately 10 kilo-ohms, which reduces to a few ohms as the temperature increases beyond 100 C. The circuit uses readily available components and can be easily constructed on any general-purpose PCB.

                                    

Here i give the link of the report file regarding of this minor project     

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