electronic card lock system
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14-01-2011, 01:57 PM

I am Kiruba,doing my engineering course,and I am want to know about the circuit diagram details of Electronic Card Lock System and its explanation.
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17-01-2011, 11:29 AM

for more on Electronic Card Lock System , please go through the following thread.

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30-10-2012, 01:07 PM


.docx   ELECTRONIC CARD.docx (Size: 521.64 KB / Downloads: 30)


The circuit presented here can be used as a lock for important electronic/electrical appliances. When card is inserted inside its mechanism, depending upon the position of punched hole on the card, a particular appliance would be switched on. The card is inserted just like a floppy disk inside the disk drive. This card should be rectangular in shape with only one punched hole on it.
The circuit uses four LDR and four white LED’s. When there is no card in lock then light is fall on LDR, the strength of LDR is adjusted by variable resistor (1kΩ). When light is fall on LDR, the resistance of LDR varies according to the incident light, so the resistance of LDR becomes low and current starts flowing through it. The LDR is connected to comparator IC (LM-324) and other input is given directly. At pin 4 and 11 the supply input is given, 5 Volt and 0 Volt respectively. The output is taken from pin no. 1, 7, 8 and 14. These output is connected to the ULN2003 and corresponding red LED’s. The ULN2003 IC works at 12 volt which is given at terminal 9 and terminal 8 makes ground. When output of LM324 is given at terminal 1, 2, 3, 4 then output is obtained at terminal 16, 15,14, 13 respectively means corresponding output is obtained and Relay’s is connected to these outputs for driving the corresponding appliances.
When card for appliance 1 is inserted then LDR of corresponding card is working and then comparator IC compare both the inputs, if output is high the signal is given to the ULN2003 and corresponding LED is glow and corresponding output of ULN is obtained at other side. Relay is connected between the ULN and appliance. When signal is applied at the Relay, it connects to the corresponding appliance for working and the appliance start working.



A light dependent resistor is a small, round semiconductor. Light dependent resistors are used to re-charge a light during different changes in the light, or they are made to turn a light on during certain changes in lights. One of the most common uses for light dependent resistors is in traffic lights. The light dependent resistor controls a built in heater inside the traffic light, and causes it to recharge over night so that the light never dies. Other common places to find light dependent resistors are in: infrared detectors, clocks and security alarms.


A light dependent resistor is shaped like a quarter. They are small, and can be nearly any size. Other names for light dependent resistors are: photoconductors, photo resistor, or a CdS cell. There are black lines on one side of the light dependent resistor. The overall color of a light dependent resistor is gold. Usually other electrical components are attached to the light dependent resistor by metal tubes soldered to the sides of the light dependent resistor.


Main purpose of a light dependent resistor is to change the brightness of a light in different weather conditions. This can easily be explained with the use of a watch. Some watches start to glow in the dark so that it is possible to see the time without having to press any buttons. It is the light dependent resistor that allows the watch to know when it has gotten dark, and change the emissions level of the light at that time. Traffic lights use this principle as well but their lights have to be brighter in the day time.


Variable resistors consist of a resistance track with connections at both ends and a wiper which moves along the track as U turn the spindle. The track may be made from carbon, cermet (ceramic and metal mixture) or a coil of wire (for low resistances). The track is usually rotary but straight track versions, usually called sliders, are also available

CAPACITOR (2200uf, 110uf):-

A capacitor is a passive electronic component consisting of a pair of conductors separated by a dielectric (insulator). When there is a potential difference (voltage) across the conductors, a static electric field develops in the dielectric that stores energy and produces a mechanical force between the conductors. An ideal capacitor is characterized by a single constant value, capacitance, measured in farads. This is the ratio of the electric charge on each conductor to the potential difference between them.


A light-emitting diode (LED) is a semiconductor light source. LEDs are used as indicator lamps in many devices, and are increasingly used for lighting. When a light-emitting diode is forward biased (switched on), electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence and the color of the light (corresponding to the energy of the photon) is determined by the energy gap of the semiconductor. LEDs present many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved robustness, smaller size, faster switching, and greater durability and reliability. Light-emitting diodes are used in applications as diverse as replacements for aviation lighting, automotive lighting (particularly brake lamps, turn signals and indicators) as well as in traffic signals. The compact size, the possibility of narrow bandwidth, switching speed, and extreme reliability of LEDs has allowed new text and video displays and sensors to be developed, while their high switching rates are also useful in advanced communications technology. Infrared LEDs are also used in the remote control units of many commercial products including televisions, DVD players, and other domestic appliances.


Voltage regulation is required. In the past, the task of voltage regulator design was tediously accomplished with discrete Devices, and the results were quite often complex and costly. Today, with bipolar monolithic regulators, this task has been significantly simplified. The designer now has a wide choice of fixed, low V Diff and adjustable type voltage regulators.
These devices incorporate many built–in protection features, making them virtually immune to the catastrophic failures encountered in older discrete designs.
The switching power supply continues to increase in popularity and is one of the fastest growing markets in the world of power conversion. They offer the designer several important advantages over linear series–pass regulators.These advantages include significant advancements in the areas of size and weight reduction, improved efficiency, and the ability to perform voltage step–up, step–down, and voltage–inverting functions. Motorola offers a diverse portfolio of full featured switching regulator control circuits which meet the needs of today’s modern compact electronic equipment.

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