26.12.2015

12v dc 1.5a power supply

Arkada?lar bir sureden beridir yuksek akymly cift yonlu hyz ayarly motor kontrol devreleri aramaktayym.
The U1 MC14490 is a hex contact bounce eliminator, it uses to de-bounce the switches and the clock for operation of the chip can also be used to driver the motor phase generator circuit. The U2 and U3 (74LS74) generate the necessary clock pulse to drive the motors, the U4 and U5 (74LS157) select the phase direction. This circuit protects against overload and short circuit, PWM range can be adjusted from 0-100%, PWM frequency is 100HZ-5KHZ adjustable.
The L6203 is a DMOS full bridge driver, which can handle the high peak current up to 5A and supply voltage up to 48V with RDS (ON) of just 0.3 ohm. The above DC motor driver circuit is implemented with L6203 chip accompanied by a L6205 current controller.
This is a circuit for controlling the speed of small DC motors, it works nicely as a speed controller for an HO or N gauge model railroad. The left half of the 556 dual timer IC is used as a fixed frequency square wave oscillator. Adjust the 10K cutoff pot so that the motor is completely off when the speed pot is fully counter clockwise.
Connect a source of 12V DC power to the DC power input, connect a DC motor to the DC motor output. The 555 Ic is wired as an astable and the frequency is constant and independent of the duty cycle, as the total resistance (R charge + R discharge, notice the diode) is constant and equal to 22Kohm (givin a frequency of about 1Khz, notice the hum). When the potentiomenter is all up, the Rcharge resistance is 1,0 Kohm (the diode prevents the capacitor to charge through the second potentiometer section and the other 1,0 Kohm resistor) , and Rdischarge is 21 Kohm, giving a 5% on duty cycle and a 1Khz frequency.
When the potentiomenter is all down, the Rcharge resistance is 21,0 Kohm (the diode prevents the capacitor to charge through the second potentiometer section and the other 1,0 Kohm resistor) , and Rdischarge is 1 Kohm, giving a 95% on duty cycle and a 1Khz frequency.
When the potentiomenter is at 50% , the Rcharge resistance is 11,0 Kohm (the diode prevents the capacitor to charge through the second potentiometer section and the other 1,0 Kohm resistor) , and Rdischarge is 11 Kohm, giving a 50% on duty cycle and a 1Khz frequency. The 555 provide good current capability to drive the mosfet fast and to drive a bipolar transistor. If you are disgusted by the 1Khz hum of the motor try to rise the frequency out of the audible range (replacing the potenziometer), but rembember that at higher frequency inductive reactance of motor rises so the the efficiency would drop.
Obviously the mosfet (or bipolar) must have enough current capability to drive the motor, so the drain (or collector) current must be equal to maximum motor current (at power supply voltage, when it is blocked). If you don't want braking in the off cycle just place a resistor in series with the snubber diode, it should rise a bit efficiency but have more inertia when slowing the motor down. There are so many ways to drive a stepper motor, Here is another circuit that use 74LS194 4 bit bi-directional universal shift register as a phase generator and UDN2543B to drive the unipolar stepper motor. The circuits below only required a single power source, The maximum power supply voltage can not exceed +20V. R1, R2, C1, D1, D2 and schmitt trigger IC1B build a 1kHz oscillator with adjustable duty cycle.
This control circuit is ideal for the accurate control of DC motors as well as other applications like lighting levels and small heaters etc. A pulse width modulator (PWM) is a device that may be used as an efficient light dimmer or DC motor speed controller. One additional advantage of pulse width modulation is that the pulses reach the full supply voltage and will produce more torque in a motor by being able to overcome the internal motor resistances more easily.


The main Disadvantages of PWM circuits are the added complexity and the possibility of generating radio frequency interference (RFI). PWM (Pulse Width Modulation) is an efficient way to vary the speed and power of electric DC motors. The purpose of a motor speed controller is to take a signal representing the demanded speed, and to drive a motor at that speed.
Motors come in a variety of forms, and the speed controller's motor drive output will be different dependent on these forms. Corporate names & trademarks mentioned herein are the property of their respective companies. We need however many times to replacement some old switch or to check currents bigger than the durability of certain switches or simple we need something with modern appearance. The oscillator signal is fed into the right half of the 556 which is configured as a variable pulse width one-shot monostable multivibrator (pulse stretcher). I suggest to not stress to much the motor with too much work because it overheats both motor, transistor and diode. The circuit converts a DC voltage into series of pulses, such that the pulse duration is directly proportion to the value of the DC voltage. The circuit described here is for a general purpose device that can control DC devices which draw up to a few amps of current. Finally, in a PWM circuit, common small potentiometers may be used to control a wide variety of loads whereas large and expensive high power variable resistors are needed for resistive controllers. RFI may be minimized by locating the controller near the load, using short leads, and in some cases, using additional filtering on the power supply leads. Here two drivers are described for 24 V (15 V to 30 V) motors with a maximum current up to 80 A.
The speed controller presented here is designed to drive a simple cheap starter motor from a car, which can be purchased from any scrap yard. Sitemizde payla?ylan tum dokumanlar (Tezler, makaleler, ders notlary, synav soru cevaplar, projeler) payla?ymcylaryn bireysel caly?malary olup telif haklary kendilerine aittir ya da acyk bir ?ekilde kamusal alana yerle?tirilmi? dokumanlaryn birer kopyalarydyr.
The output of the one-shot is a variable width square wave pulse, the pulse width is set with the speed control pot on the control voltage input. Pulse width modulation is the process of switching the power to a device on and off at a given frequency, with varying on and off times. The great advantage of such a circuit is that almost no power is lost in the control circuit.
The circuit may be used in either 12 or 24 Volt systems with only a few minor wiring changes. This circuit has some RFI bypassing and produced minimal interference with an AM radio that was located under a foot away. If it does, it is called a Feedback Speed Controller or Closed Loop Speed Controller, if not it is called an Open Loop Speed Controller.
These motors are generally series wound, which means to reverse them, they must be altered slightly, (see the section on motors).
Ki?ilerin bireysel caly?malaryny sitemizde yuklemesinde, sitemizde payla?yma te?vik eden puanlama sisteminin de etkisi buyuktur. This device has been used to control the brightness of an automotive tail lamp and as a motor speed control for small DC fans of the type used in computer power supplies.


If additional filtering is needed, a car radio line choke may be placed in series with the DC power input, be sure not to exceed the current rating of the choke.
It is highly recommended to first test the circuits with a current limited power supply and a small motor! The first driver use a power PROFET transistor switched at 500 Hz and the second use a power MOSFET transistor switched at 20 kHz.
Feedback speed control is better, but more complicated, and may not be required for a simple robot design.
Bunlara ra?men hala size ait olan ve burada bulunmasyna izin vermedi?iniz dokumanlar varsa ileti?im bolumunden yoneticilere bildirmeniz durumunda derhal silineceklerdir. This based in the known 555, which drives a relay of which the contacts play the role of switch. If the motor stall, the current goes above the 2.0A (set by R9 and R10) then the second comparator channel will toggle the enable line of U2 to actually disable the driver, this limiter will also turn on and off at a frequency of 20KHZ. The MOSFET amplifies the current of this signal so that it is powerful enough to control a small DC motor. A PWM circuit works by making a square wave with a variable on-to-off ratio, the average on time may be varied from 0 to 100 percent. The majority of the RFI will come from the high current path involving the power source, the load, and the switching FET, Q1.
Out of the four Schmitt triggers inside the 4093, U1a is wired as an oscillator with adjustable duty cycle. The metal surfaces can have what form we want, but it should they are clean and near in the circuit. In case the motor is continuously stalled then when the F1 PTC reset-able fuse reaches it cutoff temperature, it will then turn off the current to the motor to protect the chip from blowing out. The 311 comparator is used to cut off the one-shot via the reset pin when the control voltage is below a certain threshold, the 311 is also controlled by the speed control pot.
The U1b, U1c, U1d buffers the output of the oscillator to drive the switching MOSFET Q1.The MOSFET drives the DC motor according to the switching pulse obtained from the oscillator. The cut off circuit is necessary because the 556 one-shot circuit will always put out a small pulse, even when the control voltage is at zero. The main advantage of a PWM circuit over a resistive power controller is the efficiency, at a 50% level, the PWM will use about 50% of full power, almost all of which is transferred to the load, a resistive controller at 50% load power would consume about 71% of full power, 50% of the power goes to the load and the other 21% is wasted heating the series resistor. Plate JF1 in order to the contacts of RL1 close [ON] or plate JF2 in order to the contacts of RL1 open [OFF]. Load efficiency is almost always a critical factor in solar powered and other alternative energy systems. It is often taken to be an abbreviation of Conformite Europeenne, meaning "European Conformity".



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