Security Circuits

Infrared light trap circuit

This infrared light valve has more parts, so it works better and more reliable for alarms. The circuit responds less ambient light. The light valve consists of a transmitter and a receiver. The transmitter consists of a NE 555 which provides pulses to the infrared LED (D1) are fed. The frequency of the pulses is set to P1. On the receiver side we see the photo transistor T1 receives the pulses from D1. The pulses through C4 to the positive input of op amp IC2 led. Between the output of IC2 and the minus input is an RC network that ensures the lowest at about 7.2 kHz amplitude issues. ..

Wireless Bug detector

This fairly simple circuit makes it possible to place such a wall as a conduit to locate. It is a conduit for power, no water or gas-seeker. The only requirement is that there is tension on the line. The antenna in the table can consist of a simple piece of copper wire. The correct adjustment is done through R7, in order to prevent the buzzer and LEDs still light up even though there is no leadership in the area. ..

LED flasher with two transistors

This circuit will flash a bright LED 5000mcd as an intention getting device or fake car alarm...

Optical switch detector with 555

When the phototransistor is stroken by IR light it conducts and the voltage between the 1Mohm resistor(arbitrary) and the phototrans drops from VCC to lower values. When the voltage drops lower than VCC/3 the 555 is triggered and goes high (from 0 TO VCC). The amount of light that strike the phototrans necessary to bring his collector to VCC/3 is determined by the resistor (Vdrop = Icollector * R , so , if Vdrop= 2*VCC/3, the resistance needed to set the threshold on current is R=2*VCC/(Icollector*3)). ..

FM Bug detector 80 - 150 MHz

This Mini FM Bug Detector is basically a broad-band receiver. It picks up the complete band from below 80Mhz to 150MHz and almost anything that transmits in that band will be detected. If a bug with a sensitive microphone is transmitting nearby, the result will be a feedback whistle. The Bug Detector will not determine the output power of a bug as it is detecting the sensitivity of the microphone. However it will prove the carrier section is working (this is the section that produces the 88MHz frequency) and also the audio section. ..

RF wireless allarm magnetic switch PIC16F84

This circuit was formed to create a wireless alarm from a normal magnetic contact. By fixing the magnet to the leaf of a door, or swing of a drawer, it is easy to reveal the opening. To transmit the signal to a control anti-theft we modify the circuit of a remote control to activate it only for as long as necessary . Without the change, leaving the door open for the batteries would run out in a few hours! This transmitter is powered by a battery of 9 volts for a period of one year. You can connect to any kind of contact , including that of infrared sensors (PIR) to create a wireless burglar alarm. Every time one of its three entrances is closed, is a radio code to entremets Nutchip or any other circuit compatible with the encoding MM53200 , UM3750 or UM86409 . This diagram illustrates a remote fixed codes , ready to work immediately without adjustments. Moving a jumper, you can also get codes like...

Electric Fence circuit

A circuit design, based on a C-mos chip to Drive a Car Ignition Coil. This is a Very Simple and Efficient Design for an Electric Fence. It puts out a Very high Voltage Current pulse, yet it draws a very small average Current from the battery or supply. As Accurate as I can Measure, the "AVERAGE Current Draw" varies between: 20 uA at at Slow Pulse setting to about 85 uA at the fast pulse setting. So Battery life is "Really Good" and this makes a Good Electric Fence. Due to a High Peak Current Draw, this Fencer will NOT work properly, just running from a Power Adapter or a work-bench power supply. This Electric Fence Should be powered by a 12 Volt Battery and this battery. Should have a Trickle Charger on it. ..

Video Camera switcher MAX454

The video switcher described here can display the output of two, three, or four cameras on a single monitor. The number of cameras is set by a DIP switch on the circuit board. That feature avoids blank displays if less than four cameras are used by sequencing through only the inputs that are connected to a camera. In the automatic mode, the cameras are switched at a rate that can be varied with a panel mounted control. The switching rate can be set from about once per second to about once every 20 seconds. In the manual mode, one camera output is displayed continuously. A momentary-toggle switch is then used to step through the various cameras. The heart of the video switcher is a Maxim MAX454...

Door electronic lock with Keypad

It is a relatively simple circuit of electronic lock of safety with code of 7 digits. It should is given attention in the time that will be stepped the keys, that shape code and it does not exist it delays. With the right step of keys and if code is right then is activated exit Q7 for roughly 4 seconds, driving the transistor Q2, which with the line can drive one relay, for the opening of door, or any other circuit. With LED D we can have optical clue of activation. The code of circuit, as it has been given have been:1704570 but can change, if we change the connections between in the exits of IC1 and the switches...

Limit Temperature Buzzer

The circuit is small regulatorof temperature, us warns for the increase of temperature. The control of temperature becomes from the thermistor TH1, that is negative factor. His resistance is altered between in the 10K in temperature 25° C and roughly in the 1K in their 94° C. The trimmer TR1 regulates the precise temperature in which the Q1-2, connected as darlington, conduct, making him relay K1 close also the buzzer BZ, sound. The alarm is activated when the temperature becomes bigger than predetermining. The thermistor it should he is placed far from the remainder circuit, in order that this is not in danger from the temperature...

Magnetic Card Reader with PIC12F675

The reader mechanism shown was purchased from All Electronics for $1.50. The unit provides the magnetic head on a spring mechanism along with low level head signal amplifiers and data slicers. Three signal lines comming from the unit provide card presence, clock, and data. When actively reading a card, it draws about 50ma of current at 5 volts...

PC interfaced Security System

Creating a modular, networked, home control system was greatly simplified by using common 4-wire phone cable with stake-on connectors. The cable feeds both power and network signals to the various modules. Each module is made on a single sided circuit board with RJ-11 connectors (for the network / power) along with other connectors as needed. This eliminates the need for placing power feeds (wall worts) for each of the modules. The entire system runs on one power feed. Since the power feed is at least 12 volts (unregulated), very long cable runs can be used to connect to various modules. Each module has its own 5 volt regulator to run the circuit. It also means that the entire system can be run from a single 12 volt battery if the power is out...

Coil Driver/launcher circuit

This is a fun and non-dangeros project for those people who like to throw projectiles magnetically. It simply works by placing a ferromagnetic projectile at one end of a coil and pulsing some power in it. The trick is to switch off power when the projectile is at the middle of the coil, there are some ways to do it but it isn't important now. The second trick is to use a coil as close as possible to projectile to waximize coupling and the third to avoid saturation, that means keeping the current not to high. I've been messing with coil launchers for a year. The first model was a straw with some wire wrapped on it and an electrolityc capacitor (200V) pulsed in it. Lots of sparks and metal flying but was able to shoot a nail accross my room...

Fingerprint based attendance system with 8051

This project gives you a fingerprint based attendance system with 8051 microcontroller. The SM630 fingerprint module is used for fingerprint matching. It can store a max of 768 fingerprints. The admin can add/delete records from the PC through the VB application. There is an infrared LED and photo diode to sense the finger placed over the fingerprint module. All the attendance details are stored over the PC. The admin can generate reports and also he can print the reports...

The Generator cell must have reasonable surface area on the Plates to generate a reasonable amount of Hydrogen/Oxygen. And a Typical construction would use Stainless Steel for the Electrodes to prevent them from being Quickly eaten away...