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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 recorders etc. In this case, the built-in audio amplifier and loudspeaker may be omitted and the output taken across C8 and ground. There are two options: free running, when SW1 is left open, and one-shot, when SW1 is closed. In this case a two-tone cuckoo song will be generated at each P1 pressing. Cuckoo Sound Generator Circuit diagram: Parts: R1,R5___________1K 1/4W Resistors R2_____________50K 1/2W Trimmer Cermet R3______________8K2 1/4W Resistor R4_____________82K 1/4W Resistor R6______________1M 1/4W Resistor R7,R17,R20,R21_22K 1/4W Resistors R8,R10,R11,R19_10K 1/4W Resistors R9____________150K 1/4W Resistor R12_____________4K7 1/4W Resistor R13___________100K 1/4W Resistor R14___________220R 1/4W Resistor R15,R22________20K 1...

15 seconds delayed switch-off A good idea for bedroom lamps This circuit is intended to let the user turn off a lamp by means of a switch placed far from bed, allowing him enough time to lie down before the lamp really switches off. Obviously, users will be able to find different applications for this circuit in order to suit their needs. Circuit diagram : Courtesy Light Circuit diagram Due to the low current drawing, the circuit can be supplied from 220Vac mains without a transformer. Supply voltage is reduced to 10Vdc by means of C1 reactance, a two diode rectifier cell D1 & D2 and Zener diode D3. IC1 is a CMos 555 timer wired as a monostable, providing 15 seconds on-time set by R3 & C4. When SW1 is closed, IC1 output (pin 3) is permanently on, driving Triac D4 which in turn feeds the lamp. Opening SW1 operates the monostable and, after 15 seconds, pin 3 of IC1 goes low switching off the lamp. Notes: The circuit is wired permanently to the mains supply but current d...

Description: The NTE7011 is an integrated circuit in a 12−Lead SIP type package designed for use as a BTL power  amplifier with built−in headphone amp for portable stereo applications. Typical applications include  portable component stereos, car stereo, radio cassette recorders, and TV sound multiplex output. Features:  Low Quiescent Current, Low Distortion, Low Noise, High Output Power  Wide Supply Voltage range: VCC = 6 to 26V  Built−In Muting Circuit  Built−In Protection Circuits: Temperature, Surge, Overcurrent  Built−In Headphone Amplifier Circuit

This is simple Comparator Based Crystal Oscillator Circuit Project . Although a simple crystal oscillator may be built from one comparator of an LT1720/LT1721, this will suffer from a number of inherent shortcomings and design problems. Although the LT1720/LT1721 will give the correct logic output when one input is outside the common mode range, additional delays may occur when it is so operated, opening the possibility of spurious operating modes. Therefore, the DC bias voltages at the inputs have to be set near the center of the LT1720/LT1721’s common mode range and a resistor is required to attenuate the feedback to the non-inverting input. Unfortunately, although the output duty cycle for this circuit is roughly 50%, it is affected by resistor tolerances and, to a lesser extent, by comparator offsets and timings. Comparator Based Crystal Oscillator Circuit Diagram If a 50% duty cycle is required, the circuit shown here creates a pair of complementary outputs with a forced 50% duty ...

Specification : This is stereo amplifier , based on IC TDA4920 , TDA4925 , TDA4930 . Minimum voltage require 9 volts and maximum voltage 13 volts . Maximum power output 2 x 15 Watts with 4 Ohms impedance. Quiescent current 30 mA. See audio circuit scheematic below :

This is a heavier power supply that can deliver. 10A stabilized. The circuit is built around a normal 78xx controller, but for extra power equipped with T1.For the 78xx can be taken any type. Keep in mind that the input voltage of the regulator, as the output-voltage.  3V higher See 78xx power for the available controllers.T1 must be mounted on a large heatsink when installing large capacity decreased.A negative variant of this food can be found here.  10A Stabilized Circuit Diagram Warning: This diet is not short circuit proof. Parts List      R1, R2 = 0.18 Ω 5W      R3 = 2.2 Ω 2W      C1 = 22000μF      C2, C3 = 1μF      B1 = 35A      T1 = MJ15004      IC1 = 78xx

Simple Subwoofer Amplifier Circuit Diagram with 30W Output power. This circuit with 30w output Power circuit. This Amplifier circuit is very suitable for use in subwoofer amplifier system based on IC SI1030G. Amplifier has 30W output with 8 ohm impedance. Supply voltage required minimum of 12 volts and a maximum of up to 22 volts DC. Simple Subwoofer Amplifier Circuit Diagram with 30W Output power   Parts List R1 = 100K R2 = 1R C1 = 2.2uF C2 = 100uF C3 = 47uF C4 = 100nF C5 = 10uF C6 = 47uF C7 = 100uF IC = SI1020GL , SI1030G

This is an unusual circuit for an ultra-low distortion power amp. According to my original notes the circuit is dated January 1977 so the circuit is not exactly modern but it is still sufficiently different to be interesting. The circuit was designed and sold as a card by a purveyor of surplus components but, even using mostly manufacturer's rejected transistors, we managed to get about 0.02% total harmonic distortion at 30 watts with a ±25v power supply into 8 ohms.: no bad figure even in these days of MOSFET and ICs. In 1977 anything below 0.1% was considered excellent. And this figure was pretty repeatable without doing much selection.  The problem of course is that since I haven't touched this amplifier for many a year I have absolutely no idea what modern transistor types one should use for it but they are not critical: output transistors and drivers need to be the correct type but the other transistors can be small signal types - as long as they can handle the full voltag...

This FM transmitter circuit is very simple and it has a acceptable transmission . The signal transited from this FM transmitter circuit can be received at almost 300 meters in open air .The circuit require a 3volts operating voltage and can be tuned anywhere in the FM band.The coil should be about 3mm in diameter and 5 turns. The wire is tinned copper wire, 0.61 mm in diameter.After the coil in soldered into place spread the coils apart about 0.5 to 1mm so that they are not touching. If you don’t have a trim cap you can use a fixed value capacitor and you can vary the TX frequency by adjusting the spacing of the coils or placing a small piece of ferrite inside the coil , but the better way to change the transmission frequency is to use a variable capacitor .Connect a half or quarter wavelength antenna (length of wire) to the aerial point. At an FM frequency of 100 MHz these lengths are 150 cm and 75 cm respectively.

This series is the volume of the digital amplifier That is used on or tone control. This series ic type using DS1669 Digital Pot IC specifically for this volume match. a series of settings used at the middle-class amplifier That small powerless under 50 watts.volum11components: C1 = 0.1uf Ceramic, IC = IC DS1669 Digital Pot, S1 / S2 = digital swicthOr you can use the series to this one:volum2The Work: The digital volume control IC uses 9. Click to view larger. Required to operate the series voltage regulator is 12 volts. IC1 (555) is very good to work as a flip-flop. Frequency or period can be determined with selecting value of resistor R44, R45 is combined with a capacitor C6. In this series has a 0.3 second period.IC2 is used to Decrease or increase of the calculation. In the series of this mode is used to raise up and down mode is used to Decrease the volume.  While IC4 and IC3 has a 16-channel, analogue multiplexers, while working as an analog switch. IC3 is used as in the seri...

This is the Simple Sensitive RF Voltmeter Circuit Diagram. This schematic shows a peak-reading diode voltmeter driven by two stages of amplification. A 100-ILF capacitor provides a fairly large time constant, which results in satisfactory meter damping.    Simple Sensitive RF Voltmeter Circuit Diagram The limited differential output voltage coupled with an overdamped meter prevents most needle pinning when you select an incorrect range position, or make other errors. An SPST toggle switch selects additional series resistance. This X2 function gives some more overlap of the sensitivity ranges. The resistance values shown are correct for use with a 100-!LA meter with 1500-0 internal resistance.

Only a few years ago, the choice of LED s was limited to IR, red, yellow, and green. The LED manufacturers have been busy extending the spectrum, and filling in the gaps. The latest generation of organic LED s (OLEDs) has added some dazzling new colors to the spectrum. This circuit uses a set of 13 differently colored LED s to generate a full color spectrum. The photo does not fully represent the colors generated due to camera limitations. The real-world display is very eye-catching. If you want to "trick out" your PC, this circuit is for you. Forget about those boring blue PC light displays. Simple 13 Color LED Rainbow Circuit Diagram Specifications: Operating Voltage: 6-12V DC Operating Current: 145ma at 12V DC Theory: The LM2940T-5.0 low dropout voltage regulator converts the 6-12V DC input power to regulated 5 Volts. It was chosen over a standard 7805 regulator so that the circuit could maintain regulation while operating on a 6V battery. The 1N4001 diode protects the ci...

Automatic Curtain Opener Circuit Diagram . This circuit can be used with a timer clock to open and close curtains or (vertical) Venetian blinds. The curtain or blind is driven by  an electric motor with a reduction gearbox fitted to the control mechanism of the curtain or blind. This circuit is ideal for giving your home an occupied appearance while you are away on holiday or for some other reason. In the author’s house, this arrangement has provided several years of trouble-free service on a number of windows fitted  with Venetian blinds.  The original design was a simple relay circuit with pushbuttons for opening and closing and reed switches acting as limit switches. The mechanical drive is provided by a small DC motor with a reduction gearbox and pulley (all from Conrad Electronics).  It was later modified to work automatically with a timer clock. The timer operates a small  230-VAC (or 120-VAC) relay with a changeover contact. Thanks to the two timers, the ...

Power supply circuit to generate output below were variations between 1.3V DC to 12.2V DC with 1A current. In addition, the power supply circuit is also equipped with over-current protection or shield against belebih flow. Power supply circuit is very simple, but the quality is quite good, made her basiskan regulator IC LM723 is a pretty legendary. Description: R2 to set the output voltage. The maximum current is determined by R3, over-current protection circuit inside the LM723 to detect the voltage on R3, if it reaches 0.65 V, the voltage output will be off her. So the current through R3 can not exceed 0.65 / R3 although output short-circuit in his. C3 and C4 are ceramic capacitors, as much as possible directly soldered to the PCB, this is because the LM723 is prone to oscillation that is not cool. LM723 works with 9.5V input voltage to 40 V DC and the LM723 can generate its own current of 150mA when the output voltage is not more than 6-7V under input voltage. Specifications: Output...

3-channel 80 Watt audio amplifier circuit diagram

Colour Sensor Circuit diagram is an interesting project for hobbyists. The circuit 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 and digital electronics. Colour Sensor Circuit diagram : Colour Sensor  Circuit Diagram The object whose colour is required to be detected should be placed in front of the system. The light rays reflected from the object will fall on the three convex lenses which are fixed in front of the three LDRs. The convex lenses are used to converge light rays. This helps to increase the sensitivity of LDRs. Blue, green and red glass plates (filters) are fixed in front of LDR1, LDR2 and LDR3 respecti ely. When reflected light rays from the object fall on the gadget, the coloured filter glass plates determine which of the LDRs would get triggered. The circuit makes use of only ‘AND’ gates and ‘NOT’ gates. When a primary colo...

This is the Simple Temperature sensor and DVM interface Circuit Diagram. The DVM gives a direct indication of the temperature of the sensor in degrees Centigrade. The temperature sensor IC1 gives a nominal 1 µ per degree Kelvin which is converted to 10 mV per degree Kelvin by Rl and VR1. IC2 is a micropower, low input drift op amp with internal voltage reference and amplifier.   Simple Temperature sensor and DVM interface Circuit Diagram The main op amp in IC1 is connected as a voltage follower to buffer the sensor voltage at Rl. The second amplifier in IC1 is used to amplify the .2 V internal reference up to 2.73 V in order to offset the 273 degrees below 0°C.The output voltage of the unit is the differential output of the two op amps and is thus equal to 0.01 V per °C. Sourced By: Circuitsproject

This audio peak detector allows a pair of stereo channels to be monitored on a sin-gle LED. Identical circuitry is used in the left and right channels. Use is made of the switch-ing levels of Schmitt trigger NAND gates inside the familiar 4093 IC. The threshold level for gate IC1.A (IC1.B) is set with the aid of preset P1, which supplies a high-impedance bias level via R2 (R1).  Circuit diagram : Simple Audio Peak Detector Circuit Diagram  When, owing to the instantaneous level of the audio signal superimposed on the bias voltage by C3 (C2), the dc level at pins 1 and 2 (5 and 6) of the Schmitt trigger gate drops below a certain level, the output of IC1.A (IC1.B) will go High. This level is copied to the input of IC1.C via D2 (D1) and due to the inverting action of IC1.C, LED D3 will light. Network R3-C1 provides some delay to enable very short audio peaks to be reliably indicated. Initially turn the wiper of P1 to the +12 V extreme — LED D3 should remain out.  Then appl...

Description. The circuit given here is designed by Mr.Seetharaman V.S (seethasub@hotmail.com) from Chennai. Seetharaman’s comments about the circuit : This circuit is a modification of  High & Low voltage cut-off with delay& alarm circuit  appeared in Circuits today, which I have tried and found to be quite reliable. You can adopt this circuit with small modification. Use a transformer with secondary 15 – 0 – 15 AC Volt at 500mA, for 18Volt relay operation. Normally any modern electrical / electronic equipment can operate with 230 Volt ± 15% AC supply. That is, it can stand normal voltage operating range of 195 to 265 Volts. It may misbehave beyond this voltage range. You can choose the practical voltage required for the low end high cut off to change over to other phase. Circuit diagram. Connection diagram. Notes. Set VR3 for minimum voltage to switch on the relay (Say 195 Volt input). Set VR1 to switch off the relay above a particular voltage (say 260Volt input...

This analyst is, a sensitive instrument, in the frequency changes   and width of a acoustic signal. Thus the brightness of LED that turns on each moment of is proportional signal width, while the colour of proportionally frequency. Mini Audio Analyzer Circuit Diagram   . The circuit input sensitivity is regulated with R2, in order that in powerful signals they turn on the red LED , in the middle the yellow LED and in the low green LED . The display unit, is constituted by 3 lines of 10 LED the every, what is checked by a counter decoder (IC2). Two gates ICa-b, function as the IC2, with the R6 regulate the frequency. When does not exist signal in the input, then no one LED does not turn on. As soon as it will be applied signal, then the LED will begin to blink depending on the rythm and the intensity of signal. Can experiment with the prices of resistances R4, R5, so that you find the value that suits in like your. Initially it can they are placed trimmer 1KO, in th...