TREE

In the circuit, two op amps (half of an LM324 quad op amp) and an SCR are direct coupled in a de-voltage monitoring circuit. Op-amp U1-a is configured as a voltage follower, which feeds the bridged inputs of the second op amp, Ul-b. A resistor/capacitor combination (R2/C1) connected to the negative input of U1-b forms an RC time-delay circuit. Glitch Detector Circuit Schematic As long as there is no change in the de-voltage level at either of U1-b's inputs, its output is near zero. If a voltage glitch occurs, the RC timing circuit will delay the voltage change at the op amp's inverting input, causing its output to go high, triggering SCR1 and causing LED1 to light. The circuit's sensitivity allows it to detect voltage changes in the millivolt range. Pressing S1 diverts the SCR's holding current to ground, causing it to turn off and reset the circuit.

A DTMF-based IR transmitter and receiver pair can be used to realize 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), photodiode 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 fro...

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).  Audio Top Detector 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 ...

This is a simple Line Current Detector Circuit Diagram . This circuit will detect line currents of about 250 mA or more without making any electrical connections to the line.Detection of line-current flow and indicating the flow to an electrically remote point is required in line status monitoring at a variety of points in the Telephone system and auxiliary systems. The line should be minimally unbalanced or loaded by the monitor circuit, and relatively high levels of 60-Hz induced voltages must be ignored.   Simple Line Current Detector Circuit Diagram The H ll A Al allows line currents of either polarity to be sensed without discrimination and will ignore noise up to approximately 2.5 mA. In applications where greater noise immunity or polarity- sensitive line-current detection is required, the HllAlO threshold coupler can be used. This phototransistor coupler is specified to provide a minimum 10% current transfer ratio at a defined input current, while leaking less than 50 ...

This metal detector electronic project schematic circuit is designed using a simple 555 timer integrated circuit . As you can see in the schematic circuit , this metal detector electronic project requires few external electronic parts . This circuit detects metal and also magnets. Metal Detector with 555 Timer Circuit Daigram When a magnet is brought close to the 10mH choke, the output frequency changes. This metal detector project can be powered from a power supply that can provide an output DC voltage between 6 an 12 volt . If a metal is closer to the L1 coil , will produce a change of output oscillation frequency, that will generate a sound in the 8 ohms speaker

In single phase AC induction motors , often used in fridges and washing machines, a start winding is used during the starting phase. When the motor has reached a certain speed, this winding is turned off again. The start winding is slightly out of phase to the run winding. The motor will only start turning when the current through this winding is out of phase to that of the run winding. The phase difference is normally provided by placing a capacitor of several µF in series with the start winding. When the motor reaches a minimum speed, a centrifugal switch turns off the start winding. The circuit diagram doesn’t show a centrifugal switch; instead it has a triac that is turned on during the staring phase. For clarity, the series capacitor isn’t shown in the diagram. Once the motor turns it will continue to do so as long as it isn’t loaded too much. When it has to drive too heavy a load it will almost certainly stall. A large current starts to flow (as the motor no longer generate...

A Coil Coupled Operation Metal Detector made from readily obtainable components and using an ordinary medium receiver as a detector. Coil Coupled Operation Metal Detector Circuit Diagram Notes: The metal detector shown here may well represent a new genre. At any rate, after some exposure, it is regarded as such by those who have seen it. It is based on a standard transformer coupled oscillator (TCO)  hence the name Coil Coupled Operation (CCO) Metal Detector. Although requiring a BFO (in this case provided by a Medium Wave radio), it differs from a typical BFO detector in that its performance far outstrips that of BFO. Also, unlike BFO, it is dependent on the balance of two coils to boost sensitivity. It also differs from IB, in that its Rx section is an active, rather than passive, component of the oscillator. Further, unlike IB, the design does not require critical placement of the coils. As with both BFO and IB, the design provides discrimination. Experiments with different embo...

This is simple electronic Circuit Diagram Project of Low Light Level Drop Detector. This self-biasing configuration is useful any time srnall changes in light level must be detected, for example, when monitoring very low flow rates by counting drops of fluid. In this bias method, the photodarlington is de bias stabilized by feedback from the collector, compensating for different photodarlington gains and LED outputs. The 10-I`F capacitor integrates the collector voltage feedback, and the 10-MO resistor provides a high base-source impedance to minimize effects on optical performance. Low Light Level Drop Detector Circuit Diagram: The detector drop causes a momentary decrease in light reaching the chip, which causes collector voltage to momentarily rise, generating an output signal. The initial light bias is small because of output power constraints on the LED and mechanical spacing system constraints. The change in light level is a fraction of this initial bias because of stray light pa...

Build a Invisible Broken Wire Detector Circuit Diagram . Portable loads such as video cameras, halogen flood lights, electrical irons, hand drillers, grinders, and cutters are powered by connecting long 2- or 3-core cables to the mains plug. Due to prolonged usage, the power cord wires are subjected to mechanical strain and stress, which can lead to internal snapping of wires at any point. In such a case most people go for replacing the core/cable, as finding the exact location of a broken wire is difficult. In 3-core cables, it appears almost impossible to detect a broken wire and the point of break without physically disturbing all the three wires that are concealed in a PVC jacket. The circuit presented here can easily and quickly detect a broken/faulty wire and its breakage point in 1-core, 2-core, and 3-core cables without physically disturbing wires. It is built using hex inverter CMOS CD4069. Gates N3 and N4 are used as a pulse generator that oscillates at around 1000 Hz in audi...

This is the simple 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 o...

A very simple metal detector electronic project circuit can be designed using the CS209A integrated circuit manufactured by Cherry Semiconductor.The CS209A integrated circuit is a bipolar monolithic integrated circuit for use in metal detection proximity sensing applications.The CS209A metal detector contains two on-chip current regulators, oscillator and low-level feedback circuitry, peak detection/demodulation circuit, a comparator and two complementary output stages.The oscillator, along with an external LC network, provides controlled oscillations where amplitude is highly dependent on the Q of the LC tank. Metal Detector Schematic Circuit Diagram The detector, is a single 100uH coil. The IC has an integral oscillator the choke forms part of an external LC circuit, it's inductance being changed by the proximity of metal objects. It is the change in oscillation that is amplified and demodulated. Led 1 will light and the buzzer will sound when the inductance it's changed. Set...

A DTMF-based IR transmitter and receiver pair can be used to realize 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), photodiode 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 fro...