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  • Fridge door Alarm circuit

    2016-02-20 20:20:0566

    This fridge door alarm is using a 3V battery supply should be placed (in a small box) in the fridge near the lamp or close to the opening. With the doo...

  • The Circuit Diagram of CMOS alarm System (SN74LS08DR)

    2016-02-20 20:14:1964

    This article describes The Circuit Diagram of CMOS alarm System (SN74LS08DR). The content is very simple, very helpful. Components in this article can ...

  • Latching relay protective burglar alarm

    2016-02-20 20:06:4868

    A latch could simply be a relay, part of whose switched current is diverted to supplement its control current. These days, it would more likely be impl...

  • Clock-Driven Triangle-Wave Generator Circuit

    2016-02-20 19:59:1063

    U2-a, 03 and R2 operate as an integrator. Q2 and Q3 are alternately switched at 256 cycles. U2-b, Q4, Q5, and R8 through Rll arc a constant current gen...

  • BELL 103 Compatible FSK Modem Circuit

    2016-02-20 19:47:2276

    This circuit usesMM74HC942, a single chip low-speed modem which is compatible with Bell 103 standard. This Bell 103 modem circuit is run at 300 baud in...

  • Door Alarm

    2016-02-20 19:07:3970

    Hangs up on the door-handle Beeps when someone touches the door-handle from outside Circuit diagram Parts: R1 1M 1/4W Resistor R2 3K3 1 or 2W Resistor ...

  • Door Knob Touch Alarm circuit diagram

    2016-02-20 18:55:5674

    This is door knob touch alarm for your home security purpose. The alarm will be activated when someone touch the metal door knod. This circuit wont wor...

  • Speed-limit Alert circuit (BZX79C7V5)

    2016-02-20 18:51:5466

    Wireless portable unit Circuit diagram: Parts: R1,R2,R19_______1K 1/4W Resistors R3-R6,R13,R17_100K 1/4W Resistors R7,R15__________1M 1/4W Resistors R8...

  • Bell Alarm(B250C1500)

    2016-02-20 18:19:00138

    This article briefly describes the Bell Alarm (B250C1500). Although this circuit is very easy to understand, but also very practical. Circuit elements ...

  • Polyphonic DoorBell circuit

    2016-02-20 18:05:4277

    Here is an AC triggered Multitone, polyphonic doorbell. It gives eight melodious tunes for 2 minutes. On each press it will give a new tone which will ...

  • Adjustable TTL clock

    2016-02-20 17:57:2187

    Symmetry of the square-wave output is maintained by connecting the right side of R2 through resistor R3 to the output of the third amplifier stage. Thi...

  • Low Frequency Oscillator Siren Alarm Circuit

    2016-02-20 17:36:1181

    Low-frequency oscillation (LFO) is an electronic signal, which is usually below 20 Hz and creates a rhythmic pulse or sweep.These self contained alarm ...

  • How to build Four Small Transistor Alarm Circuits

    2016-02-20 17:35:4070

    Alarm A Alarm A is a practical version of the circuit featured in my Introduction To The Complementary Latch. It has both normally-open and normally-cl...

  • Water level alarm circuit

    2016-02-20 17:22:3670

    Description. Here is a simple water level alarm circuit that will produce an audible alarm when the water level reaches? a preset level.The circuit can...

  • Fire alarm using thermistor

    2016-02-20 17:15:5361

    Description. Many fire alarm circuits are presented here,but this time a new circuit using a thermistor and a timer to do the trick. The circuit is as ...

  • Musical Doorbell Circuit Diagram

    2016-02-20 17:00:1195

    Musical Doorbell Circuit Diagram This musical doorbell circuit uses UM3481 A series IC.? It is intended for applications such as toys, door bells, musi...

  • A radio wave alarm circuit

    2016-02-20 16:54:3776

    This article describes a radio alarm circuit. The circuit is very simple, I hope for your help. Circuit transmission waves, IC1a, together with a senso...

  • Alarm Circuit Built for Motorcycles

    2016-02-20 16:48:2667

    Figure 1 The circuit was designed to create an early warning alarm system against any form of theft that is significant to the owners of motorcycles or...

  • Siren alarm simulates star trek red alert

    2016-02-20 16:28:22120

    The signal starts at a low frequency, rises for about 1.15 seconds to a high frequency, ceases for about 0.35 seconds, then starts rising again from a ...

  • Alarm Clock With Day Selector(4017)

    2016-02-20 15:45:1666

    This article briefly describes the Alarm Clock With Day Selector (4017). Although this circuit is very easy to understand, but also very practical. Cir...

  • How to build A Cmos 4060 Burglar Alarm

    2016-02-20 15:42:3573

    Description This is a single zone alarm - with automatic exit, entry and siren cut-off timers. It will accommodate all the usual types of normally-clos...

  • 1 Motorcycle Alarm circuit

    2016-02-20 14:44:0065

    This article describes is a motorcycle alarmcircuit. The circuit is very useful, it is worth Duokanjibian then master the principles of the theory. In ...

  • 24 Second Shot Clock

    2016-02-20 14:32:2366

    Description: This is a circuit intended to be used in basketball shot clock. Circuit diagram Notes: To start in 24 seconds; 24s LOAD SW and Reset SW sh...

  • wire loop alarm (1N4007)

    2016-02-20 14:29:0565

    This article describes a wire loop alarm (1N4007). The principle is very simple, very practical. The circuit components can help you understand better ...

  • How to build Mains Supply Failure Alarm

    2016-02-20 14:24:5164

    Description Whenever AC mains supply fails, this circuit alerts you by sounding an alarm. It also provides a backup light to help you find your way to ...

  • How to build Fridge Door Alarm Circuit

    2016-02-20 14:09:5865

    Description This circuit, enclosed into a small box, is placed in the fridge near the lamp (if any) or the opening. With the door closed the interior o...

  • FT232R Incorporating Clock Generator Output and FTDIChip-ID

    2016-02-20 13:15:4677

    The FT232R is the latest device to be added to FTDIs range of USB UART interface Integrated Circuit Devices. The FT232R is a USB to serial UART interfa...

  • Continuously change frequency warning alarm

    2016-02-20 12:41:0761

    Low-frequency oscillation (LFO) is an electronic signal, which is usually below 20 Hz and creates a rhythmic pulse or sweep. Low frequency oscillator (...

  • Morning Alarm for babies

    2016-02-20 12:36:5773

    Here is a pleasant wake up alarm for the babies. As the morning light breaks in, the alarm gently wakes up the baby with a soothing musical note. What ...

  • Boat alarm

    2016-02-20 12:31:5567

    Potential thief alarm circuit from the ship to break the R1 and R2 is connected to 12 V to ground and remove hidden lines R1 or R2. Activates the alarm...

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