Three Flashing LED Doorbells - Battery Powered LED Circuits: These circuits combine a buzzer with one or more LED displays. When the push switch is operated - the buzzer will sound and the LEDs will flash. When the switch is released - the buzzer will stop - but the LEDs will go on flashing for another 30 seconds or so. __ Designed by Ron J.
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 __
TinyTwo Zone Alarm - Since I travel a lot during summer, I decided to build a really small alarm that could easily fit inside a pocket. However, I also demanded reliable operation, simple construction and very low power consumption. I started with CMOS
logic gates, but was soon forced to abandon the concept after a few unsuccessful (and far too complicated) takes__ copy of geocities.com/tomzi.geo page
Touch Activated Alarm - Not much to tell here as the circuit speaks for itself. The 555 can be almost any type, they are all pin-compatible. Although some CMOS
types may not have enough power to drive the transistor, in that case use an ordinary 555. C1's working voltage should be increased to 25V if you decide to go with a 12V power source. Change the value of C1 for the desired output pulse __ Designed by Tony van Roon VA3AVR
Touch switch - This circuit uses a 555 timer as the bases of the touch switch. You can learn more about 555 timers in the Learning section on my site. When the plate is touched the 555 timer is triggered and the output on pin 3 goes high turning on the LED and the buzzer for a certain period of time. __ Contact IQ Technologies
Touch Switch II - A touch switch is a switch that is turned on and off by touching a wire contact, instead of flicking a lever like a regular switch. Touch switches have no mechanical parts to wear out, so they last a lot longer than regular switches. Touch switches can be used in places where regular switches would not last, such as wet or very dusty areas. __ Contact IQ Technologies
Transistor Based Motorcycle Alarm - Motorcycle Alarm Circuits: This circuit features a timed output and automatic reset. it can be operated manually using a key-switch or a hidden switch. By adding an external relay, it will set itself automatically - and/or immobilize the machine - every time you turn-off the ignition. 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.
Transistor Based Motorcycle Alarm - Motorcycle Alarm Circuits: This is an even simpler transistor based motorcycle alarm. The circuit features a timed output and automatic reset. it can be operated manually using a key-switch or a hidden switch. By adding an external relay, it will set itself automatically - and/or immobilize the machine - every time you turn-off the ignition. 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.
Transistor based Security Siren - 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
Transistor Based Single Zone Alarm - Single-Zone Burglar Alarm Circuits: The circuit features automatic Exit and Entry delays, timed Bell Cut-off and System Reset. it has provision for normally-open and normally-closed switches and will suit the usual input devices (Pressure Mats, Magnetic Reed contacts, Foil Tape, PiRs and inertia Sensors). __ Designed by Ron J.
Two Simple Circuit Relay Based Motorcycle Alarms - Motorcycle Alarm Circuits: 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. __ Designed by Ron J.
Two-Zone Burglar Alarm - Multi-Zone Burglar Alarm Circuits: This two-zone alarm has automatic exit, entry and siren cut-off timers. So it has a particularly detailed circuit description. There's an optional One-Time-Only module. it will force the siren to switch off after the first ten minutes - and prevent the alarm from activating a second time. __ Designed by Ron J.
Ultra-Simple Circuit Voltage Probe - Detects 1.8 to 230 Volts DC or AC Minimum parts counting. Circuit diagram: Parts: D1 5 or 3mm. Red LED D2 5 or 3mm. Green or Yellow LED LP1 220V 6W Filament Lamp Bulb P1 Red Probe P2 Black Probe Device purpose: This circuit is not a novelty, but it __ Designed by Flavio Dellepiane
UltraSonic Radar - This is a very interesting project with many practical applications in security and alarm systems for homes, shops and cars. it consists of a set of ultrasonic receiver and transmitter which operate at the same frequency. When something moves in the area covered by the circuit the circuitís __ Contact IQ Technologies
Ultrasonic Sound Beam Burglar Alarm - This unique burglar alarm makes use of the invisible, inaudible ultrasonic sound beam to detect movements. Ultrasonic transducers operate at maximum efficiency when driven at 40kHz frequency. So an ultrasonic transmitter...__ Electronics Projects for You
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
Water level buzzer - Water Level Buzzer is a simple kit which will buzz when water reaches the sensor level. __ Contact IQ Technologies
Water Level Indicator with alarm - This circuit not only indicates the amount of water present in the overhead tank but also gives an alarm when the tank is full. The circuit uses the widely available CD4066, bilateral switch CMOS
IC to indicate the water level through LEDs. When the water is empty the wires in the tank are open circuited and the 180K resistors pulls the switch __ Designed by Radioland.nt.au
Whistle Responder - Beeps when hears your whistle; A gadget suitable for key-holders, games etc __ Contact Flavio Dellepiane, fladello @ tin.it
Window Charger - Keep away intruders with this compact electrified window charger. The charger produces non-lethal shocks that are strong enough to threaten intruders. The circuit uses IC CD4047 as a free-running astable multivibrator. Capacitor...__ Electronics Projects for You
Wire Loop Alarm - This circuit is a simple wire loop alarm that can be used in doorways, hallways, or any other place the tripwire will be broken by intruders. The circuit has a built in siren, but it can be replaced by a relay to drive an external siren, commercial alarm, etc __ Designed by Aaron Cake
Wire Loop Security Alarm - A wire is looped through various objects which are to be monitored. The loop wire is typically an aircraft cable but could also be any insulated stranded wire. The loop is attached to a table or desk. Should the loop be cut, the alarm is sounded . . . Hobby Circuit designed by David A. Johnson P.E.-December, 2004