Top Circuits Page 38
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The limitation of car supply voltage (12V) forces to convert the voltages to higher in order to power audio amplifiers. This supply is intended for two channels with 50W max each (of course it depends on the amplifier used). Though it can be easily scaled up....
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The operating principle of the circuit is very simple. The first Led D1 is placed in series with the resistor R2 and diode D4.An only be lit this LED indicates that the battery is ypofortismeni. For this reason Led D1 is red. If the voltage is greater than....
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As a keen cyclist I am always looking for ways to be seen at night. I wanted something that was a novelty and would catch the motorists eye. So looking around at my fellow cyclists rear lights, I came up with the idea of 'NITE-RIDER'. NINE extra bright....
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This charger will quickly and easily charge most any lead acid battery. The charger delivers full current until the current drawn by the battery falls to 150 mA. At this time, a lower voltage is applied to finish off and keep from over charging. When the....
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R1 controls the trip-point of the circuit. adjust it accordingly. to reverse the logic (have the led light up when the battery has at least X amount of power,) connect the led to ground through R4...
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this circuit uses the LM3914 and should be powered by its own battery, otherwise you might get an innacurate reading. hook the to-be-monitored battery to pin 5 of the chip...
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An LM556 dual oscillator/timer, U1, configured as a two-tone oscillator drives U2, a dual 4-watt amplifier. One of the oscillators, pins 1 to 6, contained in U1 produces the upper frequency signal of about 200 Hz, while the second oscillator, pins 8 to 13,....
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This is easy to install to the usual system. You have to find a wire which has a voltage in position `1` and then
You cut that wire. After that You install the "ADAPWIPE" between the break of wire
just like the circuits diagram....
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This small but useful circuit is a DC voltage convertor for using 6V devices with car battery voltage. The maximum output current is dependent if the T1 is covered with a proper heat sink or not. You can use the circuit to drive devices that they sink....
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This 3 volts Car Adapter circuit is based on a standard LT1074CT switching regulator IC. The schematic shows the LT1074CT used as a positive step-down or ‘buck’ converter. The ‘switcher’ is used to convert a +12-volt car battery voltage down to +3 volts for....
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The Car Voltage Gauge is based on 3 parts. The input circuit is an Analog to Digital Converter (IC2 CA3162E). The purpose of this chip is to sample an analog voltage and convert it to a decimal value which is read by a Display/Decoder Driver (IC1 CA3161E).....
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The Car Temperature Gauge is basically the same circuit as March's project with some minor changes to the input circuit. This circuit will display the water temperature to 1 degree resolution...
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A Selective Amplifier 10dB for FM/VHF region. Note that some devices to be used SMD components and may have a minimum sales volume. Device works very well as an FM external amplifier "when used for example in car / boat etc . Thanks to GF3 filter, amplifier....
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Its based on inductive pickup and very easy to install. Have a look at the pic. (remove LED and connect transistor collector to pin4). I hope it will exactly suits to your tachometer...
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Pin 3 defines the Display type: Common Cathode or Common Anode. Connect this pin to GROUND if you are using common cathode 7-segment led displays. To use common anode displays, connect it to VCC (positive)
Pin 4 is the signal input, you can use optical....
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Basically, this is a frequency-current converter. It is used as frequency meter. Calibrating it can be used as tachometer. Please be aware this is an experimental project, I didn't use it connected on any vehicle but it should work fine after calibration. It....
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Our present car controller runs on a single PIC16F870 micro and provides functions for remote door locks, headlight reminder, and car finder. It is constructed using wire-wrap to allow for future expansion and is mounted using Velcro on the passenger side....
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The usual chargers of battery automotive, are simple and cheap appliances that charge continuously the battery, with a rythm of few amperes, for the time where the appliance is ON. If the holder do not close in time the charger, the battery will overcharge....
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In Fig.1 see a DC current ? sensing switch, in which the current is applied from an 8 to 16 Volt supply. The R1 value is chosen so that it generates roughly 100 mV at the required trip current. In Fig. 2 shows how the above circuit can be made to act as a....
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The circuit, is a comparator, can measure with step of 1Volt, the voltage of battery of car. The clue of voltage become after comparison of voltage of battery, that is applied in the inverting inputs of amplifiers, with voltages of reference that are....
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This Charger Can't be used as a Power Supply, Without having a battery in place. The Battery MUST be Connected to get power out. Note: This Charger Features a Reverse polarity Indicator. Instructions: Before plugging this charger into the 110 volt line (or....
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This 3A charger was originally designed to work with small batteries like those used in motorcycles. In principle it
can be used to charge car batteries also but will take a lot longer.
The charger below charges a battery with a constant current to....
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The circuit is drawn for measurement of acceleration from 1000 mg until + 1000 mg. It can be placed in kantra'n the car and be supplied from the sheath of electric lighter. The circuit includes one indicative LED and a screen LCD. The measurement of....
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If you do not like the whip antenna on your car, you may try this alternative circuit. A one-turn loop is installed in the windscreen of the car, keeping possibly away from the metal structure of the car. This loop is terminated in a 6.5mm ring core suitable....
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This design is based on the video DVM design. Furthermore, it adds support for color, so you will get red and green semaphore lights (as those in formula 1) and sound: you will even hear the starting-horn sound! Up to 3 times are displayed on YOUR TV....
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A continuously working wiper in a car may prove to be a nuisance, especially when it is not raining heavily. By using the circuit described here one can vary sweeping rate of the wiper from once a second to once in ten seconds. The circuit comprises two....
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This very simple circuit uses a transformer ,two diodes , a capacitor and an ammeter.
To charge a battery just connect the + and - terminals of the circuit to the corresponding terminals of the battery.
When the battery is not charged, the ammeter reading....
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This charger will charge any 12V lead acid battery including flooded, gel and AGM. It is fully automatic and will charge at a rate up to about 4A until the battery voltage reaches a preset point at which it will switch to a very low current float charge. If....
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This circuit measures the distance covered during a walk. Hardware is located in a small box slipped in pants' pocket and the display is conceived in the following manner: the leftmost display D2 (the most significant digit) shows 0 to 9 Km. and its dot is....
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Multi-spark ignition is very useful especially in the case of startings at low temperature and at low rpm range. Basic idea, is to apply to spark plugs instead of only one spark, a spark-burst” having big energy. In this case, combustion of air/fuel mixture....
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The operating principle of the circuit is very simple. The first Led D1 is placed in series with the resistor R2 and diode D4.An only be lit this LED indicates that the battery is ypofortismeni. For this reason Led D1 is red. If the voltage is greater than....
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Here's a circuit to create a buzzcoil using a standard automotive ignition coil. A 556 dual timer is used to establish the frequency and duty cycle of the coil current. One of the timers is used as an oscillator to generate the 200 Hz rectangular waveform....
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Automotive electronic locks circuit principle is shown in Fig. ICl dedicated lock IC 5G058, it O ~ feet respectively external key switch to the positive power supply, which is ..
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Circuit car wipers speed controller is shown in Fig. It can easily shake wiper speed between every second to ten times per second for any change, flexible and energy saving...
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Enhancement circuit as shown in the high-frequency component of the video signal can be increased, thereby enhancing the contrast of the TV image, it can also be connected to t..
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Although the respective inputs are differential inputs, but the right amplifier is greater than the general OP bias current (800nA), so as the input coupling capacitor, confide..
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As shown by IF processing circuit (MC1350) and video detector MC1330AP combined video circuits. Is modulated depending on the image signal IF carrier frequency (45 MHz) is supp..
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As shown by a reed switch off the TV highlights cancellation circuit. Brightness potentiometer W ground a series reed, normally watch TV, the reed contact is closed, the capaci..
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As shown in FIG amplification is used to convert a variety of devices and TV video output signal, such as some VCRs, DVD players need weak output signal amplification occasions..
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As shown in FIG grounds MAX4104/4105/4304/4305 video cable driver amplifier circuit configured. MAX4104/4105/4304/4305 as a coaxial transmission line suitable for amplifying vi..
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BTS412B as two high-side power MOSFET switch and two BU271L (50v, Zhang 1n) for the low-side switch, can be composed of bi-directional H-bridge DC motor drive circuit shown in ..
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Circuit Overview Now many families have a TV, VCD, video recorders, game consoles, cameras and even DVD and other household appliances. If the above-mentioned appliances out of..
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Circuit shown in Figure, IC1, C1 composition 400HZ about low frequency oscillator; IC2, C3 composed around 37MHZ frequency oscillator; low-frequency signal from the output C2 o..
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Circuit uses two features: one is the integrated electronic tuner with AV output (commonly known as the tuner) which can be received CATV full channel TV signal into a final vi..
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This Power Supply is suitable for the Modular Burglar Alarm. However, it has other applications. It is designed to provide an output of 12-volts, with a current of up to 1-amp. In the event of mains failure, the back-up battery takes over automatically. When....
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The Keypad must be the kind with a common terminal and a separate connection for each key. On a 12-key pad, look for 13 terminals. The matrix type with 7 terminals will NOT do. The Alarm is set by pressing a single key. Choose the key you want to use and....
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Each zone uses a normally closed contact. These can be micro switches or standard alarm contacts (usually reed switches). Zone 1 is a timed zone which must be used as the entry and exit point of the building. Zones 2 - 5 are immediate zones, which will....
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Any number of normally open switches may be used. Fit the mercury switches so that they close when the steering is moved or when the bike is lifted off its side-stand or pushed forward off its centre-stand. Use micro-switches to protect removable panels and....
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The circuit above above makes use of the CMOS 4017 decade counter IC. Each depression of a switch steps the output through 0 - 9. By coupling the output via an AND gate to the next IC, a predefined code has to be input to create the output. Each PBS switch....
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This circuit emits a beep and/or illuminates a LED when someone touches the door-handle from the outside. The alarm will sound until the circuit will be switched-off. The entire circuit is enclosed in a small plastic or wooden box and should be hanged-up to....
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Reverse engineered circuit diagram of a popular retail doorknob alarm. It contains a small transmitter and the doorknob acts as an antenna so it will not work on a metal door. When a person comes close to the doorknob this loads down the oscillator and the....
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This is my electronic combination lock to use with an outdoor gate. The functionality is implemented in software. It turns on a relay (usually to open a door) for a few seconds if someone enters the valid code. This relay can operate a power-to-open type....
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This circuit is permanently plugged into a mains socket and NI-CD batteries are trickle-charged. When a power outage occurs, the lamp automatically illuminates. Instead of illuminating a lamp, an alarm sounder can be chosen.
When power supply is restored,....
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This is an enhanced 5 digit keypad which may be used with the Modular Alarm System...
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It came to me in a flash. A simple way to see if a fuse has blown without removing it from its holder.
Its not often you can design a circuit using just two components, but with just one resistor and an
LED this circuit provides visual indication of when a....
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Figure 1 represents a cheap and simple Gate Alarm, that is intended to run off a small universal AC-DC power supply. IC1a is a fast oscillator, and IC1b a slow oscillator, which are combined through IC1c to emit a high pip-pip-pip warning sound when a gate....
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The first circuit was designed for the situation where a hijacker forces the driver from the vehicle. If a door is opened while the ignition is switched on - the circuit will trip. After a few minutes delay - when the thief is at a safe distance - the alarm....
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The security system application and program offers a simple demonstration of the BASIC Serial Interface. By adding only a few door and window switches, a transistor, a siren, (see schematic) and a few lines of BASIC program (see program listing) the....
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The circuit detects a sudden shadow falling on the light-sensor and sounds the bleeper when this happens. The circuit will not respond to gradual changes in brightness to avoid false alarms. The bleeper sounds for only a short time to prevent the battery....
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This low voltage circuit can be used to monitor batteries and other volatile sources of current for problems. The circuit sounds an alarm and lights an LED, but can be interfaced to any number of other circuits for many different uses...
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This is a selection of small self-contained alarm circuits. They have a very low standby current; and are suitable for battery operation...
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Simple construction, reliable operation, very small power consumption, and, most of all, small size. I started with CMOS logic gates, but was soon forced to abandon the concept after a few unsuccessful (and far too complicated) attempts. Then I suddenly....
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This circuit features automatic Exit and Entry delays and a timed Bell Cut-off. It has provision for both normally-closed and normally-open contacts, and a 24-hour Personal Attack/Tamper zone. It is connected permanently to the 12-volt supply and its....
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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....
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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,....
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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....
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This circuit, enclosed in a small plastic box, can be placed into a bag or handbag. A small magnet is placed close to the reed switch and connected to the hand or the clothes of the person carrying the bag by means of a tiny cord. If the bag is snatched....
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This Design Idea expands on a circuit in a previous one to configure a power-outage detector with a flashing alarm (Figure 1, Reference 1). The circuit plugs into a mains outlet and uses trickle-charged nickel-cadmium batteries. The green-LED monitors the....
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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...
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A single zone alarm circuit with entry and exit delay and other facilities. 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....
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The idea behind this snore alarm, is just to rouse the snorer, not the entire household. To wake the sleeper, vibration is used, not an audible alert. The vibration is provided by a small motor housed in a small 35mm film case, which can be placed under the....
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The Sun-Up Alarm can be used to provide a audible alarm for when the sun comes up or it can be used in a dark area and detect when a light comes on. It can also be used to detect a light beam, headlights etc. The circuit works as follows. The phototransistor....
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The circuit uses a 555 timer wired as an astable oscillator and powered by the emitter current of the BC109C. Under dry conditions, the transistor will have no bias current and be fully off. As the probes get wet, a small current flows between base and....
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A circuit that offers visual indication of fluid level in a vessel, with a switchable audible alarm. Example uses would be to monitor the level of water in a bath or cold storage tank...
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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...
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3-phase power, would endanger the electrical equipment (especially asynchronous motor) security, in order to detect phase failure, it can be made with a broken alarm. Circuit s..
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Circuit works: QM-NJ9 is alcohol sensor. QM-NJ9 contact after the odor of alcohol, the resistance value A, B between the reduced..
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This is a complete alarm system with 5 independent zones suitable for a small office or home environment. It uses just 3 CMOS IC`s and features a timed entry / exit zone, 4 immediate zones and a panic button. There are indicators for each zone a "system....
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A few months ago, I decided to build a compact, yet effective alarm. My demands were:- simple construction, reliable operation, very small power consumption, and, most of all, small size. I started with CMOS logic gates, but was soon forced to abandon the....
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This circuit features automatic Exit and Entry delays and a timed Bell Cut-off. It has provision for both normally-closed and normally-open contacts, and a 24-hour Personal Attack/Tamper zone. It is connected permanently to the 12-volt supply and its....
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This switch will suit the Modular Burglar Alarm circuit. However, it also has other applications. The Keypad must be the kind with a common terminal and a separate connection for each key. On a 12-key pad, look for 13 terminals. The matrix type with 7....
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The Keypad must be the kind with a common terminal and a separate connection for each key. On a 12-key pad, look for 13 terminals. The matrix type with 7 terminals will NOT do. The Alarm is set by pressing a single key. Choose the key you want to use and....
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This is a simple single-zone burglar alarm circuit. Its features include automatic Exit and Entry delays and a timed Bell/Siren Cut-Off. It`s designed to be used with the usual types of normally-closed input devices such as - magnetic reed contacts - micro....
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This article describes a 2-Input alarm developed on the PIC LICK-1 Module using a Microchip PIC16F628-04. The program uses the internal 4MHz oscillator and if any other frequency is used, the timer values will need to be changed. A two zone alarm means the....
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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....
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This is a simple single-zone burglar alarm circuit. Its features include automatic Exit and Entry delays and a timed Bell/Siren Cut-Off. It`s easy to use. First check that the building is secure and that the green LED is lit. Then move SW1 to the "set"....
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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 of the fridge is in the dark, the photo resistor R2 presents a high resistance (>200K) thus clamping IC1 by holding....
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Beeper and/or LED remotely-operated via mains supply line. Pressing the pushbutton of the transmitter, a sound and/or light alert is activated in the receiver. The system uses no wiring or radio frequencies: the transmitted signal is conveyed into the mains....
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The project was originally intended as a present for my brothers dorm room, but a bad capacitor and the lack of a proper oscilloscope caused delays. It has not made it off the breadboard, and it probably will not until his next semester. The circuit contains....
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Inverters U1a and U1b are connected in a simple RC oscillator circuit. The frequency is determined by the values of R1, C1 C2 and the internal characteristics of the integrated circuit. As long as the circuit is oscillating, a positive dc voltage is....
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This circuit is very basic to build. To open a lock which is connected to the K1 Load, you must press each momentary switch in the correct sequence. The sequence used in this circuit is S1, S2, S3 and finally S4. If any of the other switches are pressed the....
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TCP based security system using the Ethernet module offered within the contest , an ATmega16L microcontroller , a PIR as a sensor and few other peripheral devices , which is specially targeted for homes and small business owners. I have used through for my....
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This alarm circuit is based on two 555 timers. The alarm will sound your car horn if anyone opens the car door while the circuit is armed. The timers will allow you to leave the car without sounding the horn. To turn the circuit on S1 must be closed. To set....
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his month I am making 3 different types of siren circuits based on the 555 timer. The first circuit simulates the siren of a British police car. It uses two 555 timers in the circuit. The 555 on the right is wired as an alarm tone generator and the second....
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This circuit warns the user against fire accidents. It relies on the smoke that is produced in the event of a fire. When this smoke passes between a bulb and an LDR, the amount of light falling on the LDR decreases. This causes the resistance of LDR to....
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The circuit presented here wakes you up with a loud alarm at the break of the daylight. Once again the 555 timer is used here. It is working as an astable multivibrator at a frequency of about 1kHz.
The circuit's operation can be explained as follows:
When....
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his circuit can be used as an Infrared beam barrier as well as a proximity detector.
The circuit uses the very popular Sharp IR module (Vishay module can also be used). The pin nos. shown in the circuit are for the Sharp & VIshay modules. For other modules....
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Most of the power supply failure indicator circuits need a separate power supply for themselves. But the alarm circuit presented here needs no additional supply source. It employs an electrolytic capacitor to store adequate charge, to feed power to the alarm....
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This circuit utilising a 555 timer IC can be used as an alarm system to prevent the theft of your luggage, burglars breaking into your house etc. The alarms goes ON when a thin wire, usually as thin as a hair is broken.
The circuit is straightforward. It....
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The circuit consists of a small PIC microcontroller, assembly program,
and a few other parts to detect a switch closure from an open door, window,
or manual push button and then dial the cell phone number, and transmit a
steady tone to indicate the source....