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Motor Control Circuits
Motor Control Circuits
This circuit monitors the power-line (ac) voltage. When a power failure occurs, on restoration of power, the circuit a
The PWM controller uses complementary half-H peripheral drivers SN75603 and SN75604, with totem-pole outputs rated at 40 V and 2.0 A. These drivers effectively place the motor in a full-bridge configuration, which has the ability to provide bidirectional control. Timer U1 operates in the astable mode at a frequency of 80Hz. The 100-0 discharge resistor results in an 8-p.s trigger pulse...
The controller circuit can reduce a fan"s noise, power consumption, and wear, particularly in the presence of a low, fluctuating ambient temperature. Mount a temperature sensor in the fan"s airstream, and the circuit will adjust the fan speed as necessary to maintain a relatively constant sensor temperature. Input components Rl and Cl integrate the input square wave, producing a...
In this proximity detector an NE567 tone decoder provides a signal of about 100 kHz that is fed to one sensor. The senso
DC variable speed motor control
Dc power can also be controlled via fiberoptics. The circuit provides an insulated speed control path for a small dc actuator motor (< Vn hp). Control logic is a self-contained module requiring about 300 mW at 12 V, which can be battery powered. The control module furnishes infrared pulses, at a rate of 160 Hz, with a duty cycle determined by the position of the speed adjust potentiometer. The...
Universal motor speed control
The resistor capacitor network R1-R2-C1 provides a ramp-type reference voltage superimposed on top of a dc voltage adjustable with the speed-setting potentiometer R2. This reference voltage appearing at the wiper of R2 is balanced against the residual counter emf of the motor through the SCR gate. As the motor slows down due to heavy loading, its counter emf falls, and the reference ramp...
Three-phase factor controller
The modified power-factor controller, developed at the Marshall Space Flight Center, employs a phase detector for each of the three phase windings of a delta-connected induction motor. The phase-difference sum is the basis for control.
Bi-directional motor control
The control of both direction and of proportional motor speed is achieved by rotation of a single potentiometer. The motor driver is an SGS integrated circuit L293 which will drive up to 1 amp in either direction, depending on the logic state of input 1 and input 2 as per table. I/P 1 I/P 2 Function. High Low Motor turns one way. Low High Motor reverses. By applying a variable M/S ratio...
This single time-constant circuit can be used as proportional speed control for induction motors such as shaded pole or permanent split-capacitor motors when the load is fixed
This circuit is intended as a revolution control for small dc motors as fitted, for instance, in small electric drills (
Dc Motor-Speed Control
The system shown consists of the HA-2542, a small 12-Vdc motor, and a position encoder. During operation, the encode
The NE5561 provides pulse-proportional drive and speed control based on de tachometer feedback. This simple switching circuit consists of transistor 2N4920 pnp with a commutation diode used to deliver programmed pulse energy to the motor. A frequency of approximately 20 kHz is used to eliminate audio noise. The de tach delivers 2.7 V/1000 RPM. Negative feedback occurs when this voltage is...
Motor speed control
Universal motors and shade d-pole induction motors can be easily controlled with a full-wave Triac speed controller. Q1 combines both the triac and diac trigger diodes in the same case. The motor used for the load must be limited to 6 amperes maximum. Triac Ql must be provided with a heat sink
Reversing motor drive dc control
This is a positioning servo drive featuring adjustment of balance, gain, and deadband. In addition to control from a dc signal, mechanical input can be fed into the balance control, or that control could be replaced by a pair of resistance transducers for control by light or by temperature.
This electronic motor-speed control circuit is designed to operate in an electrically noisy environment. The circuit includes an optoelectronic pickup device. whichis placed inside the motor housing to provide a speed feedback signal. The circuit automatically maintains the speed of the motor at the commanded value. The pickup device contains an infrared LED and a phototransistor. The...
Plug-in speed control for tools or appliances
Most standard household appliances and portable hand tools can be adapted to variable -speed operation by use of this simple half-wave SCR phase control. It can be used as the speed control unit for the following typical loads pro-videe they use series universal (brush type) motors. During the positive half cycle of the supply voltage, the arm on potentiometer R2 taps off a traction of the sine...
Universal motor control
When the time delay expires, SCRl conducts and removes the gate signal from SCR2, which stops the motor. Both the time delay and motor speed are adjustable by potentiometers R2 and R3. If heavier motor loads are anticipated, use the larger C30B SCR in place of the GE-X1 for SCR2
Two-phase ac motor driver
Because of its high amplification factor and built-in power-output stage, an integrated power operational amplifier makes a convenient driver for ac motors. One op amp can be configured as an oscillator to generate the required ac signal. The power-output stage, of course, supplies the high-current drive to the motor.
12-24V Impulse control dimmer
This circuit is intended for use with motors, lamps,heatings etc. Continuously from nearly zero up to maximum capacity (5-95%). Almost lossfree control by means of this impulse control. Nearly total turning moment of motors. The transistior T3 must absolutely be fastened on a heatsink with minimum dimentions of approximate 100x100x5mm. The heatsink has to be fixed insulated as the transistor...
This high-performance switching controller for a low-power de servo motor uses a symmetrical complementary- transistor bridge. The bridge acts as a reversing switch between the motor and a single-ended power supply. Since the transistors operate either fully on or completely off, except during a very short transition period, much less heat is dissipated than in linear-amplifier circuits....
The timed two-voltage circuit can start and run a small de motor or solenoid. The input voltage to the LM317 three-terminal regulator ranges from 5 to 40 V, and the output voltage can range from 2 to 36 V.
Pwm Motor-Drive Circuit Circuit
This circuit will drive a small dc motor over a wide range of speeds without stalling by controlling the duty cycle of the motor,
Dc servo bipolar control
This circuit accepts bipolar control inputs of Â± 5 V and provides a phase-chopped output to a dc load (such as a servo motor) of the same polarity as the input. The rms voltage of the output is closely proportional to the control input voltage. N-channel and p-channel TMOS devices', Ql and Q2, are connected in anti-series to form a bidirectional switch through which current can flow in either...
Pwm motor speed control
Speed control is accomplished by pulse width modulating the gates of two MGP20N45 TMOS devices. Therefore, motor speed is proportional to the pulse width of the incoming digital signal, which can be generated by a microprocessor or digital logic. The incoming signal is applied to comparator Ul, then to paralleled inverters U2, U3, and U4 that drive the two TMOS devices, which, in turn, control...
Universal-motor speed control
Simple half-wave motor speed control is effective for use with small universal (ac/dc) motors. Maximum current capability 2 amps RMS. Because speed-dependent feedback is provided, the control gives excellent torque characteristics to the motor, even at low rotational speeds
Tachometerless Motor Speed Control
This provides bidirectional speed regulation for small motors and requires no tachometer. The voltage th
This circuit uses a tachometer to generate a feedback signal which is compared to a reference supplied by the auxiliary output. When power is applied, the tachometer output is zero and the regulator output comes on, forcing current into the motor. As motor rotation increases, the negative tachometer output pulls the enable pin toward ground. When the enaole pin"s threshold voltage is...
The figure illustrates a reversible de motor drive application with adjustable speed control. The D inputs for these drivers are complementary and can be tied together and driven from the same logic control for bidirectional motor drive. The enables are tied together and driven by a pulse-width-modulated generator providing on duty cycles of 10 to 90% for speed control. A separate enable...
High-torque motor speed control
A bridge circuit consisting of two SCRs and two silicon rectifiers furnishes full-wave power to the motor. Diodes, D3 and D5, supply dc to the trigger circuit through dropping resistors, Rl. Phase delay of SCR firing is obtained by charging C2 through resistors R3 and R4 from the voltage level established by the zener diode, D8. When C2 charges to the firing voltage of the unijunction...
Speed regulator for dc motors
A four thyristor controlled bridge is used for operation in two quadrants of the torque-speed characteristics. In the trigger circuits the usual pulse transformers were replaced by self biased circuits which minimize gate power consumption and increase noise immunity. Electrical isolation is guaranteed by the use of optocouplers. The trigger pulses are generated by the comparison between an...
Speed control for model trains or cars
Low voltage speed control gives very good starting torque and excellent speed regulation
Power tool torque control
As the speed of an electric drill is decreased by loading, its torque also drops. A compensating speed control like this one puts the oomph back into the motor. When the drill slows down, a back voltage developed across the motorâ€”in series with the SCR cathode and gateâ€”decreases. The SCR gate voltage therefore increases relatively as the back voltage is reduced. The extra gate voltage...