Motorcycle Alarm #7 - Motorcycle Alarm Circuits: This is a simple transistor alarm - with a siren cut-off timer. While the thief continues to move the bike - and the normally-open trigger switch continues to open and close - the siren will continue to sound. Shortly after the bike stops moving - the siren switches off - and the alarm resets. __ Designed by Ron J.
Motorcycle Alarm #8 - Motorcycle Alarm Circuits: This transistor alarm has a siren cut-off timer - and an LED activation indicator. Shortly after the thief abandons the bike - the siren will switch off and the alarm will reset. if the LED is lighting when you return - you'll know there's been an activation while you were away. __ Designed by Ron J.
Motorcycle Alarms #5 & #6 - These are two easy to build relay-based alarms. You can use them to protect your motorcycle but they have many more applications. if you use relays with 6-volt coils they'll protect your "Classic Bike". Both alarms are very small. The completed boards occupy about half a cubic-inch 8 cc. The standby current is zero so they won't drain your battery. Circuit designed by Ron J. __ Designed by Andy Collison
Motorcyle Alarm #2 - 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. Ron has used my Asymmetric Timer as the basis for his design __ Designed by Ron J.
Multipurpose Listening Device - This circuit can detect very faint, remote sounds with a good clarity. it is useful in large conference halls, auditoria, cinema halls, lecture rooms in colleges, etc. The circuit can be...__ Electronics Projects for You
Museum Watchdog - Theft at a museum means more than just the loss of an object, as it affects the historical, artistic and scientific value of the collection as a whole. A museum watchdog...__ Electronics Projects for You
N/O: N/C Timed Burglar Alarm - This is a simple but effective alarm circuit which can reset its self after a time that you select. it has normally open and normally closed triggers which make this circuit very practical. This alarm has normally open and normally closed triggers. it's on a 555 timer so the alarm will reset it's self after a certain amount of time. The time is adjustable __
Nocturnal Animals Whisker - A low-rate flashing lamp drives away undesired visitors; Automatic on-off operation __ Contact Flavio Dellepiane, fladello @ tin.it
Novel buzzer using a relay & transformer - This novel buzzer circuit uses a relay in series with a small audio transformer and speaker. When the switch is pressed, the relay will operate via the transformer primary and closed relay contact. As soon as the relay operates the normally closed contact will open, removing power from the relay, the contacts close and the sequence repeats, all very quickly __ Designed by Andy Collison
One-button lock provides high security - 03/04/99 EDN-Design ideas (contains several designs, scroll to find this one) Figure 1 is the block diagram of an easily programmed, single-button combination lock. You operate the lock by using a series of short and long pulses from a momentary switch that masquerades as a doorbell button. The circuit uses inexpensive CMOS
logic. The retriggerable timer, T1, locks out entries made after the T1 code-entry window, thereby greatly enhancing security. The circuit in Figure 2 operates as follows: The Schmitt-trigger quad NAND gate, IC 1, debounces the code-entry switch and, with the aid of simple analog circuitry, produces separate outputs for activation times of less than and more than 0.3 sec. These outputs connect to the select gate, IC 5 __ Circuit Design by Maxwell Strange, Fulton, MD
One-Time-Only Burglar Alarm - Multi-Zone Burglar Alarm Circuits: When this alarm is activated its Siren will sound once - for up to 20-minutes. Then it will switch off and remain off. The basic circuit has a single zone with independently adjustable Exit and Entry delays. This will be adequate in many situations. However, there's also a range of Expansion Modules. These will allow you to add any number of instant Zones, Tamper Zones and Personal Attack Zones to your system. __ Designed by Ron J.
One-Time-Only Motorcycle Alarm - Motorcycle Alarm Circuits: This is a "one-time-only" alarm - with an LED activation indicator. if the bike is moved - the siren will sound for about a minute. Then it will switch off - and remain off. it won't activate a second time. it can't be activated again - until the next time the alarm is set. __ Designed by Ron J.
Opened Window or Door Alarm - Economical circuit of an electronic alarm, notifies you when your door or window is open, is presented here. This circuit wired around the Quad 2-input NAND Schmitt trigger IC 4093 (IC 1) can be powered from a standard 9V battery. Here, a normally-closed (N/C) push switch (S1) is used to monitor the door/window activity. For __ Designed by T.K. Hareendran
Oscillating Output Improves System Security - 02/06/03 EDN Design Ideas: Filter allows comparison of noisy signals - Many electronic-control systems have digital outputs that use transistors. One method of improving the security in these outputs is to use an oscillating signal to represent a logic-high state instead of a fixed voltage level (Figure 1). This type of signal, a dynamic variable, can drive the circuit shown in Figure 2 __ Circuit Design by Jorge Marcos and Ana Gómez, University of Vigo, Vigo, Spain
Over Voltage Protection - Safety devices like fuses provide protection against excess current, but do nothing for transients and short duration spikes of high voltahe on the power supply lines. This circuit uses the "crowbar" method and provides fast protection against transient voltage spikes __ Designed by Andy Collison
Panic Alarm - imagine the Panic situation in the Midnight when an intruder tries to break into the house. This Alarm will help you with its loud Police siren to abort the attempt of intrusion. With a single clap, the circuit generates the alarm for three minutes and then goes off. This is sufficient to catch the attention of neighbours. The __ Designed by D Mohankumar
Panic Plate - Useful for the elderly and ailing persons, this touch-sensitive circuit sounds a panic alarm to catch the attention of others for immediate help. The touch plate fixed on the wall near...__ Electronics Projects for You
Parked-Vehicle Highway Flasher - Often, at night, a speeding vehicle rams into another vehicle parked at the edge of a highway. Cars have parking flashers, but trucks, buses and loading rickshaws rarely have any form...__ Electronics Projects for You
Perimeter Monitor - Using a single cable such as speaker wire or doorbell cable, this circuit can be remotely positioned, for example, at the bottom of a garden or garage, and used to detect all sound in that area. The cable can be buried in a hosepipe or duct and is concealed out of sight. The mic is an ordinary dynamic mic insert __ Designed by Andy Collison
Police Car Siren - This siren circuit simulates police, fire or other emergency sirens that produce an up and down wail. __ Contact: Charles Wenzel of Wenzel Associates, Inc.
Police Electronic Siren - The sound produced imitates the rise and fall of an American police siren. When first switched on the 10u capacitors is discharged and both transistors. __ Designed by Ron J.
Police Siren - The Police Siren circuit uses two 555's to produce an up-down wailing sound. The first 555 is wired as a low-frequency oscillator to control the VOLTAGE CONTROL pin 5 of the second 555. /. __ 555-Timer
Police Siren - This circuit produces a sound similar to the police siren. it makes use of two 555 timer ICs used as astable multivibrators. The frequency is controlled by the pin 5 of the IC . The first IC (left) is wired to work around 1Hz. The 47uF capacitor is charged __ Designed by Radioland.nt.au
Powerful Security Siren-Transistors based - This circuit was requested by several correspondents. its purpose was to obtain more power than the siren circuit already available on this website (One-IC two-tones Siren) and to avoid the use of IC s. A complementary transistor pair (Q2 & Q3) is wired as a high efficiency oscillator, directly driving the loudspeaker. Q1 ensures a full charge of C2 when power is applied to the circuit__ Learning Electronics
Programmable Digital Code Lock - A programmable code lock can be used for numerous applications in which access to an article/gadget is to be restricted to a limited number of persons. Here is yet another circuit of a code lock employing mainly the CMOS
ICs and thumbwheel switches __ Designed by Radio LocMan
Programmable Home Security Alarm System. Part 1. Schematic - Part 1. in this project we design low cost high performance programmable home security system using few LDR's as an input sensors. When above sensor (s) get triggered system may dial the user specified phone number (using build-in DTMF generator) and activate the high power audio alarm and lights. All the parameters of DTMF generator, audio alarm and light interface are programmed through the RS232 serial interface.__
Programmable Home Security Alarm System. Part 2. Calibration & Testing - Part 2. Schematic Calibration and Testing. Once everything is assembled take following steps to calibrate the system, Remove IC 1, IC 2, IC 3 and IC 4 from the IC bases. Apply 18V (to 22V Max.) DC source to the power connector (J3). Check the voltage__
Protect A Vehicle-Reverse Camera - The circuit in this Design idea uses a simple comparator circuit to make a power-on time delay for an automotive rear view camera. Auto manufacturers typically power reverse-view cameras from the reverse-light circuit. in automatic-transmission vehicles, a short power pulse is applied to the camera when you shift through reverse as you go from park__
Proximity Alarm - This simple circuit is sure to have the police beating a path to your door, however, it has the added advantage of alerting you to their presence even before their footsteps fall on the doormat. The circuit transmits on Medium Wave (this is the small problem with the police). IC 1a, together with a sensor (try a 20cm x 20cm sheet of tin foil) oscillates __ Designed by Rev. Thomas Scarborough