Top Circuits Page 98
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Door intercom is very useful for home security. If you receive a door knock or door bell/alarm, you can push this intercom knob and ask the guest? to identify...
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Ever accidentally left your front door ajar and had a pet escape? Here is a smart solution to this problem. The circuit is fairly simple but a great exampl...
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If you`re expecting an important visitor but you just have to step out for a moment, an electronic doorbell memory can come in handy so you can see whether someone rang while you were out. Of course, you can`t tell whether it was the visitor you were....
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The following circuit shows about Circuit an Infrared Toy Car Motor Controller. This circuit based on the 4047 and4017 IC. Features: 16V Capacitor, 100k Resistor, Double IC. Component: IC, Switch, Diode, LED, Resistor, Capacitor, Motor, Transistor.....
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The parallel arrangement of LED backlights allows the control IC to utilize inexpensive low voltage CMOS processes as shown by the followingcircuit diagram which requires two to six white LEDs (WLEDs) in parallel. In many applications, LED backlights have....
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To drive relay you need more than 20mA the current can one pin drive. This is why you cannot connect relay directly to microcontrollers pin. To drive relay you need to connect simple amplifier made of one transistor. This circuit is more general as instead....
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I hope that this crystal set is well received by all of you. My #62 radio combines the features of some of my earlier radios. It combines the one piece approach of my #48 set and the dual detector of one of my recent sets. The coil arrangement is a dual....
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This circuit is a double tone Police sound and Single tone old ambulance sound. This circuit is usually installed on a on battery powered cars, motorcycles, ...
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This mic preamp uses the low noise IC uA739. The circuit is an example of how a good preamplifier can be designed for dynamic microphones. The IC houses tw...
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An electromagnetic field probe designed to detect changing electric and magnetic fields. The probe has switchable gain, a frequency response up to 400kHz and independent audio and meter monitoring. This EMF probe uses an inductor to locate stray....
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Diode D1 and resistor R1 provide the VDD isolation when programming the 24 pin devices. The jumper J3 must be shorted for 24 pin devices, and open circuit for 28 pin device programming. Following EEPROMs are pin compatible with their EPROMs version, ..
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When I first built the Heart rate measurement through fingertip project, the infrared LED and photodiode used for finger photoplethysmography were actually from salvaged parts, and therefore, I could not provide specifications for them in the article. As a....
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This easyelectronicbuzzercircuitbuilt based on timer works for gaining the frequency. The IC timer NE555 used as astable multivibrator operating at about 1kHz and produces a sound when switched on. The sound frequency can be adjusted by varying the 10K....
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This is electronic coin toss circuit using one CD4049 IC (Hex inverting buffer and TTL driver). This IC has six buffers and it may be used independently. The buffers may be used as simple inverters, as voltage translators, or as current drivers for....
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The circuit below consists of two `twin-T` oscillators set to a point below oscillation. To set the circuit into oscillation, we can touch the Touch Pad. Here ...
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Digital IC, Electronic Lock , Here is an electronic code lock, which can be used as a door latch or key for ignition, etc. Operation is fairly tricky and there lies the beauty of the ci...
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This is a metronome circuit that has mechanical sound character. The metronome that has mechanical sound character will make our life more fun and it would be ...
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The electronic dog repellent circuit diagram below is a high output ultrasonic transmitter which is primarily intended to act as a dog and cat repeller, wh...
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To obtain an accurate pressure value, we must remove the offset errors. There are? many basic circuit designs that is used to remove the offset errors. This...
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We can construct a tachometer using the TC9400 in the F/V mode to convert the frequency information (RPM) into a linearly proportional voltage. Then we can compare this voltage to one of n comparators (on this example using 8). The respective LED lights up....
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The herein schematic shows FAN5009 dual bootstrapped 12V high frequency MOSFET driver typical application circuit. It can be formed a complete core voltage regulator for microprocessors if combined with multi-phase PWM controller and power MOSFETs, according....
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FAN7710 Ballast Control circuit design for Compact Fluorescent Lamps electronic project...
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This circuit is a circuit FET Cascode Video Amplifier. The cascode amplifier FET loading the video features a very low input and feedback reduction is almost zero. 2N3823 was used because of low capacitance and high Yfs. Amplifier bandwidth is limited by the....
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The schematic diagram come from circuit: The Voltage Regulator With a Field Effect Transistor power supply. Go to that page to read the explanation about above power supply related circuit diagram. Feature of this transistor compensation voltage (see....
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This circuit is a series-FET Voltmeter FETVM. This FETVM to replace VTVM function while at the same time line used to clean the appliance cord. In addition, the rate of drift is far superior to vacuum tube circuit allows full-scale range of 0.5 volts is the....
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The TDA7088T can be used in mono portable and pocket radios. This is a bipolar integrated circuit. Here`s one of the application circuit diagram: When a...
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This is a FM Transmitter circuit. This circuit uses logic gates. This transmitter circuit has a RF oscillator. This oscillator uses 10.7Mhz ceramic filter and...
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Use this fm antenna amplifier in areas where the signal reception of FM stations is too bad. This circuit is just the right thing to do it. It is designed...
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Take a look at this fm spy transmitter which can be used as a bug transmitter or as diy fm bug too. It uses a single IC 74F13, one coil, a capacitor, one t...
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This FSK demodulator convert the FSK signal to serial digital signal. FSK modulation is used to transmit digital serial data, and we need to demodulate it to...
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If you have a digital voltmeter, or any voltmeter with millivolt resolution and high input impedance, then you can use this temperature-to-voltage adapter...
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The need for a device that can detect and extinguish a fire on its own is long past due. Many house fires originate when someone is either sleeping or not home. With the invention of such a device, people and property can be saved at a much higher rate with....
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Flash slaves are used when you need to supplement one flash unit with one or several more. This slave trigger simply triggers those other units. It does this by "seeing" the first flash (using a phototransistor) and triggering the other flashes a few....
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Microcontrollers family AT89C has parallel programming interface of flash memory. In order to write information we need to supply programming voltage 12V and for controlling almost all pins of ports are used. This is why parallel programming is done in....
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Once power has been applied to the circuit, the Red LEDs should all be flashing on and off together. The Yellow LEDs should be flashing on and off, but only every other Yellow LED should be on at one time. The Green LEDs will stay on at all times. The flash....
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What follows below is the schematic of Flashlight Finder circuit diagram using the LM3909, a monolithic oscillator designed to flash Light Emitting Diodes (LEDs)..
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For several years now, a rear fog lamp has been mandatory for trailers and caravans in order to improve visibility under foggy conditions. When this fog lamp is switched on, the fog lamp of the pulling vehicle must be switched of to avoid irritating....
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The following circuit schemes the Ford Probe Single Wire Door Alarm System. This Single Door Locking Wire controls both LOCK and UNLOCK which means the pulse wires have to be connected to the same vehicle wire. The system is basically uses a single wire ( )....
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Speaker relay delay controlling circuit for audio amplidier..
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Another application of FVC (frequency-to-voltage converter) is tone/frequency decoder. This circuit is used to determine the frequency band of an oscillation...
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This is a circuit of Frequency Doubler using 4011. This circuit uses one CMOS quad, two input NAND gate package type 4011. This circuit consist of two...
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The meaning of Frequency Shift Keying (FSK) is transmitting digital data over a signal path (two wires, telephone lines, AM or FM transmitter). Typically, there are only two signals transmitted. One corresponds to a logical 1 ³. the other to a logical 1 ³.....
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Frequency meter can be used in speed sensor, tachometer, or any measurement of repetitive signals. This frequency to voltage converter (FVC) can be used to turn...
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The 555 timer produces a rapid series of pulses whenever switch SI is open. These pulses are counted in groups of 16 and converted into binary form by the 7493 and applied to the 74154 (a l-of-16 decoder/demultiplexer) wired so that each of its 16 output....
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We aim to transmit more information by carrying articles. Please send us an E-mail to wanghuali@hqew. net within 15 days if we are involved in the problems of article content, copyright or other problems. We will delete it soon. ..
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We aim to transmit more information by carrying articles. Please send us an E-mail to wanghuali@hqew. net within 15 days if we are involved in the problems of article content, copyright or other problems. We will delete it soon. ..
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This relay circuit is controlled by almost any type of infrared remote controller. This circuit works on assumption that almost all remote controller use high frequency modulated infrared light. By filtering out un-modulated or low frequency modulated....
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When the resistance value of a temperature, light, pressure,? or any other resistive sensors? Rs drops below a certain point? (adjusted by a preset...
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This is a grid dip oscillator (GDO) circuit developed by Luigi Falcone. This circuit uses seven plug in coils covering 3. 0 to 30Mhz. This circuit can be connected to the a frequency meter by using The coaxial socket J2. The figure below shows the schematic....
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4QD manufacture motor speed controllers so all our H bridges are PWM. Here`s a simple switch circuit for reversing and stopping a motor without any control of speed. Two inputs, A and B, control the bridge. With both high (or open circuit) both ends of the....
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This circuit is a simple series of tone control circuit. This tone control circuits using OP-Amp LM301A. The JFET 2N3684 provides high input impedance function and low noise characteristics for a feedback buffer op-amps operated type tone control...
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This easy to construct Handy pen torch electronic circuit and low component count, uses two power white LEDs for lighting. Low volt (4. 8V dc) supply available from the built in rechargeable Ni-Cd battery pack is first converted into two channel....
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This circuit is a compact timer circuit that will keep the headlights of your car ON for about 1. 5 minutes and then turns it OFF. This circuit incorporated to your car will help you to access dark places with out the need to come back and turn OFF the head....
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high quality amplifier for headphones electronics project. no need for preamplifier. circuit diagram...
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This circuit made from an infrared phototransistor and infrared LED. This transducer works with the principle of light reflection, in this case the light is infrared. The skin is used as a reflective surface for infrared light. The density of blood in the....
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A simple Hi Fi amplifier circuit diagram with schematic for making audio amplifier,design using TDA 2616 IC, which is a stereo power amplifier, useful for radio,tape and television. Delivers 2*12 watts net 24 watts...
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LM4880 is HiFi dual audio amplifier IC from National Semiconductors. This IC is specifically designed to produce high quality audio output with a minimum number of external components. LM4880 is capable of delivering 250mW per channel into an 8 ohm load. The....
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A faster driver can supply higher peak gate current to switch the VN64GA very quicklyThe circuit uses a VMOS totempole stage to drive the high power switch..
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The power line fluctuations and cut-offs cause damages to electrical appliances connected to the line. It is more serious in the case of domestic appliances like fridge and air conditioners. If a fridge is operated on low voltage, excessive current flows....
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Yesterday I no enhance the circuit in my blog. Today lead High Current power supply 10A and Can Adjustable Voltage or Variable Voltage Regulator 2V to 36V. By...
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This motor driver deliver the power form capacitor to the motor when the capacitor is charged to 1.75V by the solar cell. After powering the motor, capacitor...
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A constant off-time control which provide a high efficiency over a wide range of output current can be used by the LT3463A dual micropower DC/DC converters with internal Schottky Diodes, as described in the following circuit diagram and the datasheet..
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Op-amps has been widely used in low frequency oscillator (frequency ...
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Function generator ranging from 0.1 Hz to 20 MHz can be easily built using MAX038 integrated circuit chip. Here is the most simple implementation of high ...
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The circuit was designed for the purpose of creating a voltmeter with high impedance that would measure Direct Current voltages across any types of circui...
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These are circuits of high impedance low capacitance buffer and high impedance low capacitance? amplifier. First figure is a high impedance low capacitance...
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This is a simple sawtooth generator circuit. The advantages of this circuit are low cost and produces an auxiliary square wave at the same frequency. This circuit can be used to sweep the frequency of another generator. Here is the circuit : A....
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This voltage-controlled oscillator circuit is very compact and has a good linearity. The author said that the precision could be better than 0. 01% If this circuit is properly constructed. Moreover, this circuit gives three different output waveforms:....
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Voltage to frequency is very useful in many situation, such as transmitting temperature measurement using standard voice radio transceiver. This circuit (see the circuit`s schematic diagram) uses only two CA3130 op-amps, but the performance is good enough.....
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An AD8205 can be used to make a high-side current sense with a low side switch. Besides AD8205, an inductive load (solenoid) and a resistive shunt are added in this circuit. The resistive shunt is placed on high-side and the switch is placed on low-side, so....
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Here is a Flasher circuit that directly derives power from AC to give brilliant flashes at the rate of one flash per second. It uses a Diac as the main ele...
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Starting from a 30 volt power supply this high voltage converter circuit can deliver a voltage between 0 to 3 kV (version 1) or from 0 to 10 kV (version 2)...
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The schematic diagram come from circuit: High Voltage Power Supply based PWM IC TL494 power supply. Go to that page to read the explanation about above power supply related circuit diagram. To supply the high voltage converter suitable source of alternating....
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The schematic diagram come from circuit: Stable Power Supply for High Voltage -100V to -1000V power supply. Go to that page to read the explanation about above power supply related circuit diagram. Stable power supply for high voltage power supply for the....
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This discrete voltage regulator has complete features that is equivalent with modern voltage regulator integrated circuit (IC). It`s not cheaper if you build discrete one like this, but it`s always interesting to study the schematic diagram to learn how it....
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The full wave phase control circuit below was found in a RCA power circuits book from 1969. The load is placed in series with the AC line and the four diodes provide a full wave rectified voltage to the anode of a SCR. Two small signal transistors are....
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This is a programmable clock timer circuit that uses individual LEDs to indicate hours and minutes. 12 LEDs can be arranged in a circle to represent the 12 hours of a clock face and an additional 12 LEDs can be arranged in an outer circle to indicate 5....
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In the circuit, 60 individual LEDs are used to indicate the minutes of a clock and 12 LEDs indicate hours. The power supply and time base circuitry is the same as described in the 28 LED clock circuit above. The minutes section of the clock is comprised of....
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This circuit provides a visual 9 second delay using a 7 segment digital readout LED. When the switch is closed, the CD4010 up/down counter is preset to 9 and the 555 timer is disabled with the output held high..
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This is a single zone alarm - with automatic exit, entry and siren cut-off timers. It will accommodate all the usual types of normally-closed input devices - such as magnetic reed contacts, foil tape, PIRs etc. But it`s easy to add a normally-open trigger.....
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This is a 1-amp variable-voltage PSU. It adjusts from about 3v to 24v: and has the added feature that you can limit the maximum output current. This is invaluable when (for example) you power-up a project for the first time or soak-test a piece of equipment..
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Most mobile chargers do not have current/voltage regulation or short-circuit protection. These chargers provide raw 6-12V DC for charging the battery pack. Most of the mobile phone battery packs have a rating of 3. 6V, 650mAh. For increasing the life of the....
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This circuit has an adjustable output timer that will re-trigger at regular intervals. The output period can be anything from a fraction of a second to half-an-hour or more - and it can be made to recur at regular intervals of anything from seconds to days....
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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 question, or to move a piece etc. In this view it is a modern substitute for the old sandglass. Useful also for....
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The circuit below illustrates powering a LED (or two) from the 120 volt AC line using a capacitor to drop the voltage and a small resistor to limit the inrush current. Since the capacitor must pass current in both directions, a small diode is connected in....
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This circuit turns-off an amplifier or any other device when a low level audio signal fed to its input is absent for 15 minutes at least. Pushing P1 the device is switched-on feeding any appliance connected to SK1. Input audio signal is boosted and squared....
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This circuit allows you to set a limit on the maximum output current available from your PSU. It`s very useful when you power-up a project for the first time - or carry out a soak-test. By setting an upper limit on the current available from your PSU - you....
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This transistor based alarm features automatic Exit and Entry delays - together with a timed Bell Cut-off and system Reset. Along with the Exit/Entry zone - the basic alarm board has one Instant Zone. This will be adequate in many situations. However - the....
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Almost all 24V power systems in trucks, 4WDs, RVs, boats, etc, employ two series-connected 12V lead-acid batteries. The charging system can only maintain the sum of the individual battery voltages. If one battery is failing, this circuit will light a LED.....
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The IR detector (IC3) controls an LM 7555 CMOS timer (IC2) which operates in mono stable mode. When the beam is broken, IC2 is triggered and its pin 3 output goes high for about half a second. This extinguishes LED1 and turns on transistor Q1 to drive a 5V....
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The circuit below is similar to the one above but can be used with a laser pointer to toggle the relay rather than a push button. The IR photo transistor Q1 (Radio Shack 276-145A) or similar is connected to the set input (pin 6). The photo transistor should....
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This circuit generates a two-tone effect very much alike the cuckoo song. It can be used for door-bells or other purposes thanks to a built-in audio amplifier and loudspeaker. Used as a sound effect generator it can be connected to external amplifiers, tape....
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Here, S1 and S2 are normally open, push to close, press button switches. The diodes can be red or green and are there only to indicate direction. You may need to alter the TIP31 transistors depending on the motor being used. Remember, running under load....
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This circuit was purposely designed as a funny Halloween gadget. It should be placed to the rear of a badge or pin bearing a typical Halloween character image, e. g. a pumpkin, skull, black cat, witch, ghost etc. Two LEDs are fixed in place of the eyes of....
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A very high quality intercom, which may also be used for room monitoring..
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Can be used agains ferocious animals or attackers, BUT REMEMBER, this device may be illegal in your state..
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Here is the circuit diagram of IC Controlled Emergancy Light With Charger or simply 12V to 220V AC inverter circuit. The circuit shown here is that of the IC controlled emergency light. Its main features are: automatic switching-on of the light on mains....