Car Alarm Sound Booster - For car alarms, emphasis should be put on hearing the audible alert and identifying it as belonging to your ‘wheels’. Unfortunately, modern car alarm systems seem to have the more or less the same alarm sound — especially if they are from the same brand. Also. must register on this site __ Designed by Published in Elecktor July/Aug, 2010
Car Anti-Theft Alarm & Immobilizer - Automobile Alarm Circuits: This car alarm circuit features Exit and Entry delays - an instant alarm zone - an optional intermittent siren output - and an automatic Reset. By adding external relays you can immobilize the vehicle and flash the lights. __ Designed by Ron J.
Car Battery Saver - Prevents the complete discharge of the battery; when the door is left open accidentally __ Contact Flavio Dellepiane, fladello @ tin.it
Car Porch Guard - Protect your costly vehicle from theft using this electronic safety system. The system immediately switches on the porch lamp and sounds a loud alarm as soon as it detects any attempt...__ Electronics Projects for You
Cash Box Guard - Most thefts happen after midnight when people enter the second phase of sleep called 'paradoxical sleep.' Here is a smart security circuit for your cash box that thwarts the theft attempt...__ Electronics Projects for You
Chain Link Fence Alarm - Long stretches of steel fence can be monitored using the simple circuit below. An insulated wire is woven through the links in the fence. Where the fence begins, the circuit is connected to an earth ground and the security wire. At the end of the fence,. . . Circuit by Dave Johnson P.E.-October, 2005
Circuit keeps wandering children & pets nearby - 12/02/10 EDN Design Ideas: The receiver circuit in Figure 1 sounds an audio alarm when the transmitter (Figure 2) moves beyond a designated perimeter. The transmitter, a voltage-controlled oscillator, operates at approximately 915 MHz in the unlicensed iSM (industrial/scientific/me __ Circuit Design by Tom Au-Yeung and Craig Sakamoto, Maxim Integrated Products, Sunnyvale, CA
4060 Alarm - This is a single zone alarm - with automatic exit, entry and siren cut-off timers. it will accommodate all the usual types of normally-closed input devices - such as magnetic-reed contacts - foil tape - PiRs etc. __ Designed by Ron J.
4060 Burglar Alarm - Single-Zone Burglar Alarm Circuits: This is a single zone alarm - with automatic exit, entry and siren cut-off timers. it will accommodate all the usual types of normally-closed input devices - such as magnetic reed contacts, foil tape, PiRs etc. But it's easy to add a normally-open trigger. When the alarm is activated - the siren will sound for a fixed length of time. Then it will switch off - and remain off. The alarm will not reactivate. The Circuit Description offers a good introduction to both the CMOS
4060 - and the SCR. __ Designed by Ron J.
Based Motorcycle Alarm - Motorcycle Alarm Circuits: This circuit features an intermittent siren output and automatic reset. it can be operated manually using a key-switch or a hidden switch; but it can also be wired to set itself automatically when you turn-off the ignition. By adding external relays you can immobilize the bike, flash the lights etc. it's easily adapted for a 6-volt system - so it will protect your "Classic Bike". - Now With Free SiMetrix Circuit Simulation. __ Designed by Ron J.
Based Single Zone Alarm - Single-Zone Burglar Alarm Circuits: This circuit features automatic Exit/Entry delays, timed Bell Cut-off and System Reset. it has provision for normally-open and normally-closed switches and will accommodate the usual input devices (Pressure Mats, Magnetic Reed contacts, Foil Tape, PiRs and inertia Sensors). __ Designed by Ron J.
Based Vehicle Anti-Theft Alarm - Automobile Alarm Circuits: This car alarm circuit features Exit and Entry delays - an instant alarm zone - an optional intermittent siren output - and an automatic Reset. By adding external relays you can immobilize the vehicle and flash the lights. __ Designed by Ron J.
Single Zone Alarm - Single-Zone Burglar Alarm Circuits: This circuit features automatic Exit/Entry delays, timed Bell Cut-off and System Reset. it will accommodate the usual normally-closed input devices (Magnetic Reed contacts, Micro Switches, Foil Tape and PiRs). And - with a simple modification - a normally-open trigger may be added. __ Designed by Ron J.
Combination Digital Lock - A multiple input combination loack using CMOS
counter IC 's. Flexibility and code change is allowed by changing output connections. __ Designed by Andy Collison
Combination Lock - Combination lock are nice to enable alarms, but are useful for controlling a wide range of electric devices. These software keys can open gates, garages, TV sets, telephones, VCRs, well pumps in practice this circuit is capable to lock or time all the devices that can be connected to relays. __ Designed by Projects & Ideas from Nutchip.com
Combination Lock - The Circuit Board is Designed to accept 2 types of Drive transistors. I Used a 2N3906 in this schematic, but for Higher Current Drive for a Solenoid, You can use Various T0-220 PNP types of transistors. USE ONLY ONE OR THE OTHER, NOT BOTH. in the Picture, I just put a Resistor and LED, where the Solenoid should go. __ Designed by G.L. Chemelec
Combination lock - Operate your gate or something different by this simple electronic combination lock. The combination can have a chosen length of numbers or alphabets, and can be changed any time. The LCD display is optional, the circuit works fine without it. After entering the correct combination, a relay is operated for the predefined time __ Designed by Peter Jakab
Combination Locks - This circuit uses 4013 D-type bi-stable flip-flops (D stands for data). Each flip-flop has a data input and a clock input. The voltage applied to the input is transferred to the Q output at the instant when the clock input goes from 0 to 1. (We say these flip-flops are "edge-triggered".) Switches 1, 2, 3 and 4 are the switches which form the code and any number of "wrong" switches can be connected, in parallel, at the point shown. __ Designed by © David Hoult
Combination Lock - a digital lock with keypad - enter the correct code to operate a solenoid. Based around ua3731 __ Contact P. Townshend - EduTek Ltd
Combination Lock2 - a digital lock with switches. A nifty circuit i'm chuffed with, based around just 2 logic ICs ! __ Contact P. Townshend - EduTek Ltd
Current Limiting Bench Power Supply - Power Supply Circuits: This is a 1-amp variable-voltage PSU. it adjusts from about 3v to 24v: and has the added feature that you can limit the maximum output current. This is invaluable when (for example) you power-up a project for the first time or soak-test a piece of equipment. __ Designed by Ron J.
Cut Phone Line Alarm - Burglars, rapists and other criminals will often cut a phone line before they break into a home. The cut phone line will prevent many alarm systems from alerting the police. The battery powered circuit below will sound an alarm when the unit. . . Circuit by David A. Johnson P.E.-October, 2005
Cut Phone Line Detector - A while ago I got an email asking for the schematic of a circuit to detect cut phone lines. it didn't take me long to find this circuit in Electronics Now. When the circuit detects that a phone line has been cut, it activates a MOSFET which can be used to drive a relay, motor, etc. it can also be connected to a security system __ Designed by Aaron Cake
Cut Phone Line Detector - This circuit speaks for itself. When the phone line is okay, Q1 acts as a short with a very high ohms value via R1, R2, and R3 for a total of about 66 MegOhm so very high. When the phone line is cut (Tony van Roon's open) , it activates the MOSFET (Tony van Roon's Q3) via transistor Q2 to drive the load. Substitutes are fine, none of the components are critical __ Designed by Tony van Roon VA3AVR