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In this circuit power supply is given by Pressing switch Sw(1).when we press the Sw(1) it shorts the N/O contact of relay RL(1) which gives the supply to our circuit.The current which passing thorough resistor R8 gives the base current to transistor T5.Where the transistor T2 and T3 are making darlington pair. A darlington pair has various applications associated with it and one of them is to use it as a switch. As the transistor's collector current is proportionally limited by its base current, it can be used as a current-controlled switch.And transistor T4 ON when over or under voltage is given to transistor T3. Where capacitor C2 is used for avoiding noise.where capacitor C2 with resistor R10 making a low pass filter which also gives us sufficient time delay. There is a resistor network(VR1,R11,R12) which is used as a current sensor.Where zener diode ZD1 and ZD2 are used for the over voltage protection. where capacitor C1 used as a noise filter of switching circuit and Diode D3 ...

Pumping of water into a tank is accomplished by motor operation. When the tank is about to be full with water, the motor pump is about to stops to operate. When the tank is about to be emptied, the motor pump will start to operate. Float Switch Motor Pump Control Operation Figure below (A) shows a tank half filled with water. The motor pump M at idle condition. Water flows out from the gate valve L. Lever C is tilted downward to the right because of the weight W1. Mercury B is at the right position inside the glass container A. the metal rods X and Y inside the sealed glass container A are at open condition. Float bulb K float over the water J inside the tank. Float bulb K goes down as the water drops down. (A) Water is withdrawn from the tank. Water level drops downward. When the water level drops down beyond the stopper E, Figure below (B) the stopper E prevents float bulb K to go down further. When the water level goes down further weight W2 the effect of the combined weight of flo...

DC motor driver with H-Bridge IC L293D IC H Bridge DC motor driver L298 has two H-Bridge circuit in it, so it can be used to download the drive two DC motors. H Bridge DC motor driver L298 each can deliver currents up to 2A. However, in use, the H Bridge DC motor driver L298 can be used in parallel, so the ability to deliver the H Bridge DC motor driver L298 flow into 4A. The consequences of the installation of H Bridge L298 DC motor driver with the parallel mode, you need 2 pieces Bridge H L298 DC motor driver to control two DC motors using H bridge DC motor driver L298 in parallel mode. H Bridge Pin IC L298 DC motor driver which is connected in parallel operation mode: * OUT1 connected to OUT4. * OUT2 OUT3 linked. * IN1 is connected to IN4. * IN2 connected to IN3. * ENABLE ENABLE A linked to B. OUT1/OUT4 and OUT2/OUT3 associated with DC motors to be controlled. Please note that the output of the L298 does not have a safety diode. Thus, the need to add two diodes - flyback diodes, wit...

A3952S motor driver is capable of continuous output currents up to 2 A and has an operating voltages range up to 50 V. Warning , the 50 operating voltage is to power the motor , for the logic controller you will need a 5 volts Dc power supply . DC Servo Motor Circuit  Diagram This simple DC servo motor circuit design that can be used in various electronic projects . As you can see in the circuit schematic this Dc servo motor driver schematic circuit use just one integrated circuit and other few external electronic components . With bidirectional dc servo motors, the PHASE terminal can be used for mechanical direction control. Similar to when braking the motor dynamically, abrupt changes in the direction of a rotating motor produce a current generated by the back EMF. The current generated will depend on the mode of operation.

The CDI ignition circuit produces a spark from an ignition coil by discharging a capacitor across the primary of the coil. A 2uF capacitor is charged to about 340 volts and the discharge is controlled by an SCR. A Schmitt trigger oscillator (74C14) and MOSFET (IRF510) are used to drive the low voltage side of a small (120/12 volt) power transformer and a voltage doubler arrangement is used on the high voltage side to increase the capacitor voltage to about 340 volts. A similar Schmitt trigger oscillator is used to trigger the SCR about 4 times per second. The power supply is gated off during the discharge time so that the SCR will stop conducting and return to it's blocking state. The diode connected from the 3904 to pin 9 of the 74C14 causes the power supply oscillator to stop during discharge time. The circuit draws only about 200 milliamps from a 12 volt source and delivers almost twice the normal energy of a conventional ignition circuit. High voltage from the coil is about 10K...

This simple circuit and program listing allows the Maximite microcomputer (SILICON CHIP, March-May 2011) to control a stepper motor. It could be expanded to allow for the control of multiple motors, with four of the Maximite’s external I/O pins used to control each motor with identical driver circuits. A ULN2003 Darlington transistor array (IC1) switches current through the stepper motor’s two windings in either direction. When one of the four Maximite output pins (8, 12, 16 & 20, corresponding to I/Os 19, 17, 15 & 13) goes high, the corresponding output pin on IC1 goes low, sinking current through a motor winding. Conversely, when these pins are high, the corresponding Darlington transistor is off and so no current flows through that portion of the winding. Maximite Stepper Motor Interface Circuit Diagram The centre tap of each motor winding is connected to a current source comprising PNP Darlington transistor Q1 and some resistors. The maximum current is determined by the res...

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...

When using a servo motor in a project, if the servo motor does not respond as per the input, how to make sure that the fault is not in the servo motor but the circuit or logic? One way is to isolate the servo motor from the circuit and check its proper working by feeding it pulses of varying width and checking the angle that the servo motor turns to. For example, a 1.5ms pulse should make the motor turn to a 90-degree position (neutral position). Circuit diagram: Servo Motor Tester Circuit Diagram The circuit presented here generates pulses of varying widths. It is built around two NE555 timer ICs (IC1 and IC2) and a few discrete components. Timer IC1 is configured as an astable multivibrator with a time period of 20 ms. Every 20 ms, the astable provides a very sharp negative pulse to trigger IC2. Timer IC2 is configured as a monostable multivibrator that produces 1ms, 1.5ms and 2ms long pulses to rotate the servo motor (M1). Pin 4 of IC1 is pulled down by resistor R2. When switc...

DC Motor Speed Controller Circuit Diagram . This circuit takes advantage of the voltage drop across bridge rectifier diodes to produce a 5-position variable voltage supply to a DC fan or other small DC motor. It is not as efficient as a switch-mode circuit but it has the virtues of simplicity and no switching hash. The four full-wave bridges are connected so that each has two pairs of series diodes in parallel, giving a voltage drop of about 1.4V, depending on the load current. DC Motor Speed Controller Circuit Diagram The rotary switch should have "make before break" contacts which should be rated to take currents up to about an amp or so. For higher currents, higher rated bridge rectifiers and a suitably rugged rotary switch (or solenoids) will be required. If you want smaller voltage steps, you could use the commoned AC inputs on the bridge rectifiers to give intermediate steps on the speed switch. Author: Stephen Butcher,

Here is a low-cost and simple wireless stepper motor controller using infrared signals. Using this circuit you can control the stepper motor from a distance of up to four meters. The circuit comprises transmitter and receiver sections. The communication between the transmitter and receiver sections is achieved through infrared signals. Wireless Stepper Motor Controllers Circuit Diagram In the transmitter section, timer NE555 ICs (IC1 and IC2) are configured as astable multivibrators with frequencies of around 1 Hz and 38 kHz, respectively. The output of IC1 is given to reset pin 4 of IC2, so the 38kHz carrier signal is modulated by 1Hz modulating signal. The modulated signal from pin 3 of IC2 is transmitted by the infrared LED.  Resistor R5 limits the current through the IR LED. The transmitted signal is sensed by IR receiver module TSOP1738 (IC6) of the receiver section and its output at pin 3 is used as clocks for dual flip-flop 74LS74 Ics (IC3 and IC4), which are configured as a...