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Most thefts happen after midnight hours when people enter the second phase of sleep called ˜paradoxical sleep. Here is an energy-saving circuit that causes the thieves to abort the theft attempt by lighting up the possible sites of intrusion (such as kitchen....
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This light activated relay circuit presented here uses the 555 timer IC and a light dependent resistor or LDR to form a light sensitive relay in an intruder alarm system or for switching on a lamp at Sun set and off at Sun rise. Potentiometer R1 value must....
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Many fire alarm circuit is published in different website. But, here in this website is a simple and inexpensive project of fire alarm using thermistor. where thermistor is used astemperaturesensor of fire alarm. Working principle of thermistor is same as....
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Here`s a simple experiment with LDR and CD4093. This is just a modification of a previous project dark sensor using 2 transistors . In this project, the CD4093 is configured in such a way that whenever you block light falling on LDR, the circuit starts....
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This is a design for fire alarm circuit. This circuit is based on a LDR and lamp pair for sensing the fire. The alarm will works by sensing the smoke produced during fire. The circuit produces an audible alarm when the fire breaks out with smoke. This is the....
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This kit is the most basic, practical circuit to build using an LDR to turn on a relay. The two transistors connected as a Darlington pair give the circuit enough sensitivity, while the trimpot give sensitivity adjustment. The switching point of the....
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Colour sensor is an interesting project for hobbyists. The cir- cuit can sense eight colours, i.e. blue, green and red (primary colours); magenta, yellow and cyan (secondary colours); and black and white. The circuit is based on the fundamentals of optics....
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The device serves to quickly establish the status of an indicative power cells. I built it for his children, so they can determine the degree of self-discharge batteries in a variety of toys. WAS tester designed to test the fast primary (zinc, alcaline)....
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I Specifically Designed this circuit to charge 2 Batteries for my Digital Cameras, but it can be modified to charge 3, 4, 5 or more cell. However, It will Not Work with only One Cell as that voltage is too low for even this LDR Discharge Regulator. If you....
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This simple circuit using a single transistor turns ON the relay when light falls on the LDR. The potentiometer is adjusted for the required sensitivity. The power supply is 6V. Be careful about the impedance of the relay. Its impedance should not be less....
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Where it really shines is in the univibe. The 'vibe uses a dual section, reverse log taper pot that's just a bit easier to find than a dinosaur's tooth. If we notice that the pot is really wired as two variable resistors, we can use an LED/dual LDR module....
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This circuit is intended to drive the various lights decorating the crib prepared during Christmas season at many homes in Latin Countries, especially for children delight, in order to obtain realistic light-effects...
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The circuit of the mains current detector is shown in Figure 1. By using a few cheap diodes, a resistor, LED and LDR, a simple opto-isolated detector can be created. This entire circuit dissipates very low power, and can safely be housed in a heatshrink....
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The gain control element is a Light Dependent Resistor (LDR). These are blessed with a few very useful features for our purposes, one of which is low distortion even at quite high signal levels. Being light activated, all we need is a LED to provide....
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These two projects , Wah and Fuzz, are the results of a modification to a Morley dual channel volume control pedal that one of my sons suggested I undertake as He had no use for the volume unit but thought I could modify the pedal into a Wah unit. I decided....
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Integrated-circuit U1-an LF351 or 741 op amp-is used as a comparator to control the light. Resistors R2 and R3 provide a reference voltage of about 2.5 volts at pin 3 of U1. When daylight falls on light-dependent resistor LDR1, its resistance is low: about....
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This circuit is intended for children fun, and can be installed on bicycles, battery powered cars and motorcycles, but also on models and various games and toys. With SW1 positioned as shown in the circuit diagram, the typical dual-tone sound of Police or....
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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 LDR`s were hand-picked. Got two packages of them from Radio Shack, looking for at least two pairs of similar parts. Then added wire-wrap pin sockets, to the circuit, so that the LDR`s could be plugged in. Currently, the 0.33UF cap is not being used on my....
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The first circuit energizes the relay when the light rises above the preset level. The second circuit energizes the relay when the light falls below the preset level. The two circuits are practically identical. The only difference between them is the....
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Double-tone Police sound Single-tone old ambulance sound This circuit is intended for children fun, and can be installed on bicycles, battery powered cars and motorcycles, but also on models and various games and toys. With SW1 positioned as shown in the....
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Light Sensitive Switch is a simple project which operates a relay when the light falling on the LDR goes below a set point. ..
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Beeps 7.5 seconds after a preset time Adjustable time settings: 15 s. 30 s. 1 min. 2 min. & others This circuit is intended for alerting purposes after a certain time is elapsed. It is suitable for table games requiring a fixed time to answer a....
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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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This circuit is a phaser circuit, as used in guitar foot-pedal effects. It used 11 sections of op-amp such as LM324 but others will do. The whole circuit works of a dual rail supply: +/- 9v. The 0v rail is indicated by a chassis sign. Make sure these....
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The circuit shown here is used to switch on a lamp when the tele- phone rings, if the ambient light is insufficient. The circuit uses only two ICs and it can be implemented very easily. A light dependent resistance (LDR), with about 5 kilo-ohms resistance in....
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This Remote control Jammer device it’s useful when we need to block someone to use the remote control (children that change frequently the channels at tv). This remote control jammer it’s very simply and it use two infrared Leds which continuously transmit....
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If you have access to a Lowe HF-225 shortwave receiver, then you might be interested in this page. If you don`t, then you`d probably be better off leaving now. What follows is a project I completed some time ago, which allows the Lowe HF-225 to be controlled....
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As you can see, there is only one regulated 12 volt supply operating the entire circuit. I was able to do this simply by AC coupling the received signal to U3 via C10. This allowed me to adjust the offset within an operating window. By using a tantalum....
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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....