In this project a protoype circuit which can switch on the device when the light falls on it. For this I will use LM358 IC which is operational amplifier. I have made the circuit with LDR and few more components. But when I interchange the LDR with photodiode, phototransistor and transistor (L14F1) my circuit works well without changing any other components. Before understanding the circuit which I have developed, first let’s have a look on the components used in the circuit.LM358 consists of two independent, high gain operational amplifiers in one package. Important feature of this IC is that we do not require independent power supply for working of each comparator for wide range of power supply. LM358 can be used as transducer amplifier, DC gain block etc.
Fading LEDs
The circuit described here can be used to develop a fake alarm. In this system, LED’s glows slowly, becomes brighter and then dims again. This circuit is based on LM358 IC which is an operational amplifier.LM358 consist of two independent high gain operational amplifier in one package. Important feature of this IC is that we don’t need independent power supply for working of each comparator for wide range of power supply. LM358 can be used as transducer amplifier, DC gain block etc.LM358 has large dc voltage gain of 100dB. This IC can be operated on wide range of power supply from 3V to 32V for single power supply or from ±1.5V to ±16V for dual power supply. And it also supports large output voltage swing.The circuit described here uses an opamp to produce a triangular wave, which makes LED’s glow slowly, get brighter and then slowly become off. Similar cycle is repeated.
Suitcase Security Alarm
This small alarm circuit protects your valuables from thefts by engaging the alarm when somebody attempts to pick up your suitcase.It can be operated with the [[wysiwyg_imageupload::]]help of 3V therefore power consumption is also very less.It uses very less components that why it can be easily fit on the suitcase. Due to its small size you can easily carry this small alarm while you are travelling.The circuit is build around IC LM358 which is a low power transducer amplifier. The important component of this circuit is piezo sensor. Piezo sensor converts vibration or pressure into electrical signal. This same piezo element can be found inside the buzzer or you can purchase the same from market. Its working is somewhat similar to capacitors. Piezo element holds the charge when potential applied, until it is mechanically disturbed or some vibration will be there.