Rain Detector schematic

Here's a simple rain detector circuit. It uses a sensor made of a small piece of etched PC board and a simple SCR circuit to detect rain and sound a buzzer. The SCR could also be used to activate a relay, turn on a lamp, or send a signal to a security system.

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Rain Detector Circuit

Rain Detector Using 555 is a simple alarm that can be used to find out when rain was came. Rain Detector Using In principle this is an a stable multivibrator 555 which is prepared by IC555 with a sensor attached that can detect water. A stable multivibrator with the 555 is set in the audio frequency with a frequency of 1 KHz. Rain Detector circuit 555 can be supply with voltage source that is free enough from 5-15 VDC.

Circuit Rain Detector can be mounted on motorcycle, car or other object that we want to protect from rain. Water sensor used in the circuit  Rain Detector Using IC 555.  We can make with a PCB that we make the path as shown in the image above by using aluminum foil  board or insulator boards.

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Zero Crossing Detector Circuit

Zero Crossing Detector circuit is basically an application of a comparator. In the article series Zero Crossing Detector with Op Amp is built using a comparator of an Op Amp IC741/351. The process of detection of this comparator is  0Volt input signal crossing point by making reference value at comparator 0Volt.

 The output of the Zero Crossing Detector circuit with Op Amp is wave-shaped box that detection result of the crossroads of 0 volt input signal. Read More

Simple Water Level Detector

It is easy make a simple water level detector circuit. To monitor the filling of a bath, a water-tank, or a swimming pool, or to warn when a gully is overflowing, here’s a very simple water level detector built around a CD4011 CMOS quad NAND chip. Gates IC1.A and IC1.B are wired as an astable multivibrator. The oscillator frequency is determined by C1, R2 and preset P1.

Water Level Detector Circuit Diagram :


When quiescent, resistor R1 pulls the input to gate IC1.A down to logic low, which there-fore by default blocks the operation of the oscillator in the absence of water. When water is present between the e+ an d e−electrodes, IC1. A is taken high, enabling the oscillator. The output signal from gate IC1.B is shaped by IC1.C to obtain a rectangular waveform. Gate IC1.D inverts the signal so that transistor T1 is held of f in the absence of water, which avoids current flowing in the primary of transformer TR1 when the system is at rest. TR1 is a 12 V 1.5 VA AC power transformer wired as a step-up trans-former i.e. with the low-volt age winding connected to T1. The transformer’s step up ratio affords ‘passive’ amplification of the signal present at the drain of T1. The trans-former’s high voltage winding is connected to piezo sounder BZ1 (e.g. Murata; the ‘28’indicates the diameter) which produces the audible warning.

In order to optimise the sound output of the unit, you’ll need to adjust P1 so as to set the oscillator frequency to the resonant frequency of the piezo transducer; this setting can be done by ear. The electronics and batteries can be housed into a salvaged case (for example, the kind of oval box found inside giant chocolate ‘surprise’ eggs). The electrodes, formed from simple rigid copper wires, pass out through the case; the join is made watertight using epoxy adhesive.

Author : André Thiriot  - Copyright : Elektor

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Room Noise Detector Schematic Circuit

This circuit is intended to signal, through a flashing LED, the exceeding of a fixed threshold in room noise, chosen from three fixed levels, namely 50, 70 & 85 dB. Two Op-amps provide the necessary circuit gain for sounds picked-up by a miniature electret microphone to drive a LED. With SW1 in the first position the circuit is off. Second, third and fourth positions power the circuit and set the input sensitivity threshold to 85, 70 & 50 dB respectively. Current drawing is 1mA with LED off and 12-15mA when the LED is steady on.

Circuit diagram :

Room Noise Detector Circuit diagram

Parts List :

R1____________10K 1/4W Resistor
R2,R3_________22K 1/4W Resistors
R4___________100K 1/4W Resistor
R5,R9,R10_____56K 1/4W Resistors
R6_____________5K6 1/4W Resistor
R7___________560R 1/4W Resistor
R8_____________2K2 1/4W Resistor
R11____________1K 1/4W Resistor
R12___________33K 1/4W Resistor
R13__________330R 1/4W Resistor

C1___________100nF 63V Polyester Capacitor
C2____________10µF 25V Electrolytic Capacitor
C3___________470µF 25V Electrolytic Capacitor
C4____________47µF 25V Electrolytic Capacitor

D1_____________5mm. Red LED

IC1__________LM358 Low Power Dual Op-amp

Q1___________BC327 45V 800mA PNP Transistor

MIC1_________Miniature electret microphone

SW1__________2 poles 4 ways rotary switch

B1___________9V PP3 Battery

Clip for PP3 Battery

Use :

• Place the small box containing the circuit in the room where you intend to measure ambient noise.
• The 50 dB setting is provided to monitor the noise in the bedroom at night. If the LED is steady on, or flashes bright often, then your bedroom is inadequate and too noisy for sleep.
• The 70 dB setting is for living-rooms. If this level is often exceeded during the day, your apartment is rather uncomfortable.
• If noise level is constantly over 85 dB, 8 hours a day, then you are living in a dangerous environment.

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Circuit diagram Detector Cell phone

Detector Cell phone circuit diagram

This cellular buzz detector schematic ambit can faculty the attendance of an activated adaptable corpuscle buzz from a ambit of one and-a-half meters. If a RF arresting is detected the ambit will acquaint you application a complete anxiety (beep complete ) and a blinking LED .

In this blazon of ambit (that use aerial abundance 0.9-3Ghz ) you can not use an LC ambit for abundance affability .The ambit uses a 0.22μF deejay capacitor (C3) to according the RF ambit to ensure the adequacy of the ambit to abduction the adaptable buzz arresting .

This cellular buzz detector can ascertain any action of a adaptable buzz : admission or approachable SMS , video manual or articulation manual . The C3 capacitor charge accept leads breadth of 18 mm with 8 mm agreement amid leads to access the adapted abundance . This baby deejay capacitor acts as a baby gigahertz bend antenna to aggregate the RF signals .

The CA3130 operational amplifier IC is acclimated as a accepted to voltage advocate .This cellular buzz detector cyberbanking ambit diagram can be acclimated to verify the attendance of an alive cellular buzz in the activated breadth .

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Light Level Droplets Detector Circuit

Here’s a design circuit for Low-Light Level Drop Detector. This circuit utilize self-biasing configuration to detect small changes in light level. This circuit usually used in monitoring very low droplets rates. The collector of the transistor gives feedback that is used to stabilize the bias of the photo darlington. This is the figure of the circuit;

 

The effect on optical performance is reduced by a high base-source impedance that is produced by The 10-μF capacitor and 10-MΩ resistor. When there is a liquid drop is detected by the detector, the light that reach the chip is momentary decreased causing collector voltage to momentarily rise, then output signal is generated. Due to mechanical spacing system constraints and output power constraints on the LED, the initial light bias is small. A fraction of this  initial bias is the change in light level. This fraction is caused by stray light paths and drop translucence. When biased, the output signals level is still acceptable because the photodarlington  has high sensitivity. This compares with unacceptable bias point stability and signal levels when biased conventionally, like signal output across the collector bias resistor and base open. [Circuit diagram source: seekic.com]

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Simple Sensitive Vibration Detector Alarm Circuit

Whether it is the hi-fi next door, the cat purring quietly, or a knock at the door, the detector described here does not miss a thing. Whenever it picks up a sound or vibration, it emits an ear-piercing tone.
The circuit is based on the use of an 8 S2 loudspeaker as microphone/ loudspeaker. As the signals from this microphone are very small, they are I amplified in A1 and rectified. The, resulting DC signal is then compared with a reference voltage in.A2. When a noise or vibration is picked up by the microphone, the voltage at the inverting input of A2 (pin 6), rises suddenly to about 4 V and then slowly decays to 0 V. The decay time depends on the time constant W R6/C3.

 The voltage at the non-inverting input of A2 (pin 5) is held constant at 0.7 V by R3/R4. When the input at pin 6 rises above 0.7 V, the output of A2 (pin 7) instantly switches to -4 V, which causes the squarewave oscillator A3 to start. The frequency (tone) of the oscillator can be adjusted by preset potentiometer Pl. The oscillator output (pin 8) is fed to amplifier stage Tl which drives the loudspeaker. The oscillator will continue to run however, so C3 charges steadily and will keep the output at pin 7 of A2 negative. As this is not the purpose of the circuit, the incoming signal must be interrupted somewhere in the chain. To do this, an FET, T2, is used as a switch. As soon as the output of the comparator becomes negative, D3 conducts, T2 is cut off and the incoming signal is interrupted. When C3 has discharged to the extent that the voltage across it drops to below 0.7 V, the output of A2 (pin 7) becomes positive, D3 is cut off and T2 conducts.

This should, however, not happen too rapidly, otherwise there is the risk that a false alarm may be given. Therefore, the gate (drive input) of T2 is connected to earth via capacitors C2 and C8. The consequent delay ensures that the circuit is not reactivated before half a second after the loudspeaker has gone quiet. The earth potential is fixed by the voltage divider R9/R10 and im- pedance converter A4, which derive a symmetrical supply of i 4.5 V from the 9 V battery. When T1 conducts, the supply voltage will drop a little because a battery cannot deliver energy as well as a mains power supply. It can therefore happen that the output signal of A3 is superimposed on the supply voltage. This undesired feed- back should be prevented by C5 and C6. lf in spite of these capacitors diffi- culties are encountered, it may be beneficial to increase the values of R5, C2 and C8 by trial and error. lf that fails to improve matters, increase the value of capacitors C5 and C6.

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Mains Voltage Detector

The detector is intended to sense and signal to another circuit that an appliance is connected to the mains voltage. For this purpose, an optocoupler, IC1 in the circuit, is used. The light-emitting diode in this device is connected across the mains voltage rectified by bridge B1. The mains voltage is applied to this bridge via potential divider R1-C1-R2. When the capacitor has a value as specified in the diagram, the current through the diode is about 700 µA (for a mains voltage of 230 V). This results in sufficient light to make the photo-transistor conduct. The drop across the LED is about 1V.


The detector draws a current only when the monitored equipment is switched on. It is intended to be built into the appliance whose mains connection is to be monitored and must, of course, be connected behind the mains on/off switch. A possible application of the detector is in the preamplifier described in this blog (‘DIY: From vinyl to compact disc’). When it senses that the record player is being switched on, it can be used to link the Line-In input of the soundcard automatically to the preamplifier. Another possible application is its use as a power-on reset circuit in a protection system.


Transistor T1 can switch currents of up to 10mA; in the prototype, the knee voltage of the transistor was around 200mV at a current of 20mA. The maximum permissible switching voltage of the optocoupler is 30 V. Fuse F1 is added to allow a fuse to be omitted on the monitored appliance.


Resistors:

• R1,R2 = 100Ω
• R3 = 100kΩ
• Capacitors:
• C1 = 10nF 250VAC (class X2)
• C2 = 47µF 25V radial

Semiconductors:

• B1 = B250C1500
• T1 = BC547B
• IC1 = CNY65

Miscellaneous:

• K1,K2 = 2-way PCB terminal block, pitch 7.5mm
• F1 = fuse holder with fuse (rated as required)
  

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Shadow Detector Alarm Wiring diagram Schematic

This is also known as Sun up alarm, in this schema you can set the LDR’s sensitivity by 100k potentiometer, you can set it with any lamp around your room (tube light, bulb, LED etc) by varrying the 100k potentiometer. We can also control the buzzer time by 1M potentiometer 

You can Enhance this project and set the sensitivity of the LDR with a lazer light and keep it on the way of any door schema at one side and lazer at other side of the door and a then you can make this project to buzz as soon as some one enters in a room 

I personally set this project in my room with sensitivity of tube light and whenever i came in and turn my room’s tube light on

rookieelectronics

Parts Required: 100k & 1M potentiometers  10k, 1Mx(3), 47k 0.1mF, 0.01mF & 10mF LDR BC337 transistor Beeper/Buzzer 9v Battery Supply

   Circuit Diagram:

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Environmental Noise Ratio Detector Wiring diagram Schematic

This schema 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 schema uses two operational amplifiers, in the first position SW1 schema 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

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