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This electroinc Circuit Project of  Mobile phone detector circuit can sense the presence of an activated mobile cell phone from a distance of one and-a-half meters. If a RF signal is detected the cell phone detector circuit will inform you using a sound alarm (beep sound ) and a blinking LED . In this type of circuit (that use high frequency 0.9-3Ghz ) you can not use an LC circuit for frequency tuning. Mobile Phone Detector Circuit Diagram: The circuit uses a 0.22μF disk capacitor (C3) to according the RF circuit to ensure the capability of the circuit to capture the mobile phone signal .This cellular phone detector can detect any activity of a mobile phone : incoming or outgoing SMS , video transmission or voice transmission . The C3 capacitor must have leads length of 18 mm with 8 mm spacing between leads to obtain the desired frequency .  This small disk capacitor acts as a small gigahertz loop antenna to collect the RF signals  . The CA3130 operational amplifier IC i...

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...

A DTMF -based IR transmitter and receiver pair can be used to realise a proximity detector. The circuit presented here enables you to detect any object capable of reflecting the IR beam and moving in front of the IR LED photo detector pair up to a distance of about 12 cm from it. The circuit uses the commonly available telephony ICs such as dial-tone generator 91214B/91215B (IC1) and DTMF decoder CM8870 (IC2) in conjunction with infrared LED (IR LED1), photo diode D1, and other components as shown in the figure. A properly regulated 5V DC power supply is required for operation of the circuit. The transmitter part is configured around dialer IC1. Its row 1 (pin 15) and column 1 (pin 12) get connected together via transistor T2 after a power-on delay (determined by capacitor C1 and resistors R1 and R16 in the base circuit of the transistor) to generate DTMF tone (combination of 697 Hz and 1209 Hz) corresponding to keypad digit “1” continuously. LED 2 is used to indicate the tone output ...

Since his letter-box is outdoors  and quite some way from the  house, the author was looking  for a simple means of knowing if  the postman had been without  having to go outside (contrary  to popular belief, the weather  isn’t always fine in the South of  France). Circuits for this kind of  ‘remote detection’ come up regularly, but always involve running cables between the letter- box and the detection circuit in  the house. Seeking to avoid running any extra cables, the author  had the idea of using the existing cables going to the doorbell,  conveniently located adjacent to  his letter-box.   The letter-box has two doors:  one  on  the  street  side  for  the  postman, and one on the gar-den side for collecting the post.  A  micro switch  is  fitted  to  the  street-side door, to light an indicator in the house showing that  the postman has been. A second  micro switch is fitted to the door  on the garden side, to turn off  the indicator once the post has  been collected. The only ...

Proximity Detector Circuit Diagram. This proximity detector is constructed using an infrared diode detector. Infrared detector can be used in various equipment such as burglar alarms, touch free proximity switches for turning on a light, and solenoid-controlled valves for operating a water tap. Briefly, the circuit consists of an infrared transmitter and an infra-red receiver (such as Siemens SFH506-38 used in TV sets).   The transmitter part consists of two 555 timers (IC1 and IC2) wired in astable mode, as shown in the figure, for driving an infrared LED. A burst output of 38 kHz, modulated at 100 Hz, is required for the infrared detector to sense the trans mission; hence the setup as shown is required.  To save power, the duty cycle of the 38kHz astable multivibrator is maintained at 10 per cent.  The receiver part has an infrared detector comprising IC 555 (IC3), wired for operation in monostable mode, followed by pnp transistor T1. Upon reception of infrared signals,...

This is a simple project of Laser Level Detector Circuit Diagram. Rotating laser levels, which are very handy  for setting objects in a room or garden at the  same height, are available at prices of a few  dozen pounds. At relatively large distances  and for outdoor use, the light from the rotating laser beam is often not easy to see, and  the laser beam detector described here can  be useful in such situations. The detector  works well at distances up to 50 metres (150  feet) and consists entirely of standard components. The detector is housed in a plastic case  that can be fixed to an object (such as a post  or a beam). It has three LEDs and a beeper that  indicate whether the object should be raised  or lowered. . . LEDs with a transparent package and integrated lens (round surface) are used as sensors. The top and bottom detection zones  each have five LEDs and two opamps (IC1a &  IC1b or IC1c & IC1d), whic...

This circuit is  good for finding component causing incidence trouble voice at radio-set of receiver. Have been realized that in this time a lot of radiation of broadcaster which cannot be arrested by radio receiver limpidly. Sometime - sometime original voice lose to be swallowed  trouble - other voice trouble . So long as in installation each every real correct component, circuit will function properly . Besides can be used for look for the source of voice trouble . This appliance can be made to look for trouble at radio receiver which  not sound at all . Part List : R1=220K R2=4K7 Vr1=100K Vr1=100K C1=10pF C2=1uF C3=1uF L1=100R D1=OA70 Q1=BC327 Q2=TIP42C S1=Switch On/of G1=6V battery Tp=Test Pad SP=Speaker connector To determine the level of interference , then the required injector which is connected with one leg and foot trimpot polar + diode crystal. To be more easier then made the switch as circuit above, the switch is derived from the meeting  trimpot legs t...

Rain Detector using SCR 106CY This circuit uses a sensor made of a small piece of circuit board and recorded a simple SCR circuit to detect rain and sound of a bell. The SCR could also be used to activate a relay, light a lamp, or send a signal to a security system. 1. The sensor is a small piece of PC board etched to the pattern showen in the schematic. The traces should be very close to each other, but never touching. A large spiral pattern would also work. 2. Make sure to use a loud buzzer.

This proximity detector using an infrared detector (Fig. 1) can be used in various equipment like automatic door openers and burglar alarms. The circuit primarily consists of an infrared transmitter and an infrared receiver. Fig. 1: IR proximity detector The transmitter section consists of a 555 timer IC functioning in astable mode. It is wired as shown in the figure. The output from astable is fed to an infrared LED via resistor R4, which limits its operating current. This circuit provides a frequency output of 38 kHz at 50 per cent duty cycle, which is required for the infrared detector/receiver module. Siemens SFH5110-38 is a much better choice than SFH506-38. Siemens SFH5110-38 is turned on by a continuous frequency of 38 kHz with 50 per cent duty cycle, whereas SFH506 requires a burst frequency of 38k to sense. Hence, SFH5110-38 is used. The receiver section comprises an infrared receiver module, a 555 monostable multivibrator, and an LED indicator. Upon reception of infrared si...

This circuit have applied to line detection of robot project, Good match between the transmitter and the detector is important for proper operation, especially if the hole is large. Circuit diagram : Infrared Emitter & Detector Circuit Diagram Robot with a simple object or obstacle detection. Infrared Transmitter detector pair sensors are relatively easy to implement, although involved some degree of testing and calibration in order to make correct. They can for the impediment, motion detection, transmitters, encoders are used, and the color detection. This can be done with a piece of rope stretched between and in accordance with LED and phototransistor. A length of stiff wire or plugs can be used to set the alignment. Another method that can be used for long distances is a laser pointer shone through a hole. Source / detector alignment method The transmitter can be mounted above the track with the phototransistor placed between the rails in places like hidden deposits. Plac...

Square, triangular, sawtooth, and pulse waves are typical examples of nonsinusoidal waveforms. A conventional ac voltmeter cannot be used to measure these nonsinusoidal waveforms because it is designed to measure the RMS value of the pure sine wave. One possible solution to this problem is to measure the peak values of the nonsinusoidal waveforms. Read More.....

This circuit is  good for finding component causing incidence trouble voice at radio-set of receiver. Have been realized that in this time a lot of radiation of broadcaster which cannot be arrested by radio receiver limpidly. Sometime - sometime original voice lose to be swallowed  trouble - other voice trouble . So long as in installation each every real correct component, circuit will function properly . Besides can be used for look for the source of voice trouble . This appliance can be made to look for trouble at radio receiver which  not sound at all . Part List : R1=220K R2=4K7 Vr1=100K Vr1=100K C1=10pF C2=1uF C3=1uF L1=100R D1=OA70 Q1=BC327 Q2=TIP42C S1=Switch On/of G1=6V battery Tp=Test Pad SP=Speaker connector To determine the level of interference , then the required injector which is connected with one leg and foot trimpot polar + diode crystal. To be more easier then made the switch as circuit above, the switch is derived from the meeting  trimpot legs t...

A very simple PIR motion detector circuit can be designed using this diagram. This project PIR sensor PIR motion detector circuit, operational amplifier, a sound generator circuit and use some other common electronic components. The op-amp IC1D shapes the frequency response to amplify those frequencies produced when motion is detected and rejects all others, such as those due to noise or slow temperature changes. As motion is detected, the voltage at the output will change and trigger either IC1C or IC1B.The op-amps IC1A, IC1B and IC1C are configured as voltage comparators. PIR Motion Detector Circuit Diagram: When IC1D outputs a voltage lower than 1.41V, it will force pin 2 of IC1 high. When IC1D outputs a voltage higher than 1.67V, it forces pin 8 and pin 2 of IC1 to go high. A high in with one of these cases causes the output to go low and allows C9 to discharge through IC1A. The discharging of C9 will pull pin 6 of IC2 low and trigger the sound generator. The Passive Infrared Senso...

This circuit is called the detector noise environment , and also indicates by means of a flashing LED when exceeding the limit specified in the environmental noise, chosen from three fixed levels. This circuit uses two operational amplifiers, in the first position SW1 circuit is not connected, positions 2, 3 and 4 define the input sensitivity threshold to 85, 70 and 50 dB, respectively. Environmental Noise Ratio Detector Circuit Diagram Parts List R1 = 10K R3 R2 = 22K R4 = 100K R5, R9, R10 = 56K R6 = 5K6 R7 = 560R R8 = 2K2 R11 = 1K R12 = 33K R13 = 330R C1 = 100nF C2 = 10μF 25V CAP 470UF 25V C3 = C4 = 47μF 25V D1 = LED red IC1 = LM358 Q1 = BC327 MIC1 = Miniature electret microphone B1 = 9V